/* * Copyright (c) 2005, 2025, Oracle and/or its affiliates. All rights reserved. * Copyright (c) 2023, Alibaba Group Holding Limited. All rights reserved. * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. * * This code is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License version 2 only, as * published by the Free Software Foundation. * * This code is distributed in the hope that it will be useful, but WITHOUT * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License * version 2 for more details (a copy is included in the LICENSE file that * accompanied this code). * * You should have received a copy of the GNU General Public License version * 2 along with this work; if not, write to the Free Software Foundation, * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. * * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA * or visit www.oracle.com if you need additional information or have any * questions. * */ #include "classfile/classLoaderData.inline.hpp" #include "classfile/classLoaderDataGraph.hpp" #include "classfile/javaClasses.inline.hpp" #include "classfile/symbolTable.hpp" #include "classfile/vmClasses.hpp" #include "classfile/vmSymbols.hpp" #include "gc/shared/gcLocker.hpp" #include "gc/shared/gcVMOperations.hpp" #include "gc/shared/workerThread.hpp" #include "jfr/jfrEvents.hpp" #include "jvm.h" #include "memory/allocation.inline.hpp" #include "memory/resourceArea.hpp" #include "memory/universe.hpp" #include "oops/fieldStreams.inline.hpp" #include "oops/klass.inline.hpp" #include "oops/objArrayKlass.hpp" #include "oops/objArrayOop.inline.hpp" #include "oops/oop.inline.hpp" #include "oops/typeArrayOop.inline.hpp" #include "runtime/arguments.hpp" #include "runtime/continuationWrapper.inline.hpp" #include "runtime/frame.inline.hpp" #include "runtime/handles.inline.hpp" #include "runtime/javaCalls.hpp" #include "runtime/javaThread.inline.hpp" #include "runtime/jniHandles.hpp" #include "runtime/os.hpp" #include "runtime/threads.hpp" #include "runtime/threadSMR.hpp" #include "runtime/vframe.hpp" #include "runtime/vmOperations.hpp" #include "runtime/vmThread.hpp" #include "runtime/timerTrace.hpp" #include "services/heapDumper.hpp" #include "services/heapDumperCompression.hpp" #include "services/threadService.hpp" #include "utilities/checkedCast.hpp" #include "utilities/macros.hpp" #include "utilities/ostream.hpp" #ifdef LINUX #include "os_linux.hpp" #endif /* * HPROF binary format - description copied from: * src/share/demo/jvmti/hprof/hprof_io.c * * * header "JAVA PROFILE 1.0.2" (0-terminated) * * u4 size of identifiers. Identifiers are used to represent * UTF8 strings, objects, stack traces, etc. They usually * have the same size as host pointers. * u4 high word * u4 low word number of milliseconds since 0:00 GMT, 1/1/70 * [record]* a sequence of records. * * * Record format: * * u1 a TAG denoting the type of the record * u4 number of *microseconds* since the time stamp in the * header. (wraps around in a little more than an hour) * u4 number of bytes *remaining* in the record. Note that * this number excludes the tag and the length field itself. * [u1]* BODY of the record (a sequence of bytes) * * * The following TAGs are supported: * * TAG BODY notes *---------------------------------------------------------- * HPROF_UTF8 a UTF8-encoded name * * id name ID * [u1]* UTF8 characters (no trailing zero) * * HPROF_LOAD_CLASS a newly loaded class * * u4 class serial number (> 0) * id class object ID * u4 stack trace serial number * id class name ID * * HPROF_UNLOAD_CLASS an unloading class * * u4 class serial_number * * HPROF_FRAME a Java stack frame * * id stack frame ID * id method name ID * id method signature ID * id source file name ID * u4 class serial number * i4 line number. >0: normal * -1: unknown * -2: compiled method * -3: native method * * HPROF_TRACE a Java stack trace * * u4 stack trace serial number * u4 thread serial number * u4 number of frames * [id]* stack frame IDs * * * HPROF_ALLOC_SITES a set of heap allocation sites, obtained after GC * * u2 flags 0x0001: incremental vs. complete * 0x0002: sorted by allocation vs. live * 0x0004: whether to force a GC * u4 cutoff ratio * u4 total live bytes * u4 total live instances * u8 total bytes allocated * u8 total instances allocated * u4 number of sites that follow * [u1 is_array: 0: normal object * 2: object array * 4: boolean array * 5: char array * 6: float array * 7: double array * 8: byte array * 9: short array * 10: int array * 11: long array * u4 class serial number (may be zero during startup) * u4 stack trace serial number * u4 number of bytes alive * u4 number of instances alive * u4 number of bytes allocated * u4]* number of instance allocated * * HPROF_START_THREAD a newly started thread. * * u4 thread serial number (> 0) * id thread object ID * u4 stack trace serial number * id thread name ID * id thread group name ID * id thread group parent name ID * * HPROF_END_THREAD a terminating thread. * * u4 thread serial number * * HPROF_HEAP_SUMMARY heap summary * * u4 total live bytes * u4 total live instances * u8 total bytes allocated * u8 total instances allocated * * HPROF_HEAP_DUMP denote a heap dump * * [heap dump sub-records]* * * There are four kinds of heap dump sub-records: * * u1 sub-record type * * HPROF_GC_ROOT_UNKNOWN unknown root * * id object ID * * HPROF_GC_ROOT_THREAD_OBJ thread object * * id thread object ID (may be 0 for a * thread newly attached through JNI) * u4 thread sequence number * u4 stack trace sequence number * * HPROF_GC_ROOT_JNI_GLOBAL JNI global ref root * * id object ID * id JNI global ref ID * * HPROF_GC_ROOT_JNI_LOCAL JNI local ref * * id object ID * u4 thread serial number * u4 frame # in stack trace (-1 for empty) * * HPROF_GC_ROOT_JAVA_FRAME Java stack frame * * id object ID * u4 thread serial number * u4 frame # in stack trace (-1 for empty) * * HPROF_GC_ROOT_NATIVE_STACK Native stack * * id object ID * u4 thread serial number * * HPROF_GC_ROOT_STICKY_CLASS System class * * id object ID * * HPROF_GC_ROOT_THREAD_BLOCK Reference from thread block * * id object ID * u4 thread serial number * * HPROF_GC_ROOT_MONITOR_USED Busy monitor * * id object ID * * HPROF_GC_CLASS_DUMP dump of a class object * * id class object ID * u4 stack trace serial number * id super class object ID * id class loader object ID * id signers object ID * id protection domain object ID * id reserved * id reserved * * u4 instance size (in bytes) * * u2 size of constant pool * [u2, constant pool index, * ty, type * 2: object * 4: boolean * 5: char * 6: float * 7: double * 8: byte * 9: short * 10: int * 11: long * vl]* and value * * u2 number of static fields * [id, static field name, * ty, type, * vl]* and value * * u2 number of inst. fields (not inc. super) * [id, instance field name, * ty]* type * * HPROF_GC_INSTANCE_DUMP dump of a normal object * * id object ID * u4 stack trace serial number * id class object ID * u4 number of bytes that follow * [vl]* instance field values (class, followed * by super, super's super ...) * * HPROF_GC_OBJ_ARRAY_DUMP dump of an object array * * id array object ID * u4 stack trace serial number * u4 number of elements * id array class ID * [id]* elements * * HPROF_GC_PRIM_ARRAY_DUMP dump of a primitive array * * id array object ID * u4 stack trace serial number * u4 number of elements * u1 element type * 4: boolean array * 5: char array * 6: float array * 7: double array * 8: byte array * 9: short array * 10: int array * 11: long array * [u1]* elements * * HPROF_CPU_SAMPLES a set of sample traces of running threads * * u4 total number of samples * u4 # of traces * [u4 # of samples * u4]* stack trace serial number * * HPROF_CONTROL_SETTINGS the settings of on/off switches * * u4 0x00000001: alloc traces on/off * 0x00000002: cpu sampling on/off * u2 stack trace depth * * * When the header is "JAVA PROFILE 1.0.2" a heap dump can optionally * be generated as a sequence of heap dump segments. This sequence is * terminated by an end record. The additional tags allowed by format * "JAVA PROFILE 1.0.2" are: * * HPROF_HEAP_DUMP_SEGMENT denote a heap dump segment * * [heap dump sub-records]* * The same sub-record types allowed by HPROF_HEAP_DUMP * * HPROF_HEAP_DUMP_END denotes the end of a heap dump * */ // HPROF tags enum hprofTag : u1 { // top-level records HPROF_UTF8 = 0x01, HPROF_LOAD_CLASS = 0x02, HPROF_UNLOAD_CLASS = 0x03, HPROF_FRAME = 0x04, HPROF_TRACE = 0x05, HPROF_ALLOC_SITES = 0x06, HPROF_HEAP_SUMMARY = 0x07, HPROF_START_THREAD = 0x0A, HPROF_END_THREAD = 0x0B, HPROF_HEAP_DUMP = 0x0C, HPROF_CPU_SAMPLES = 0x0D, HPROF_CONTROL_SETTINGS = 0x0E, // 1.0.2 record types HPROF_HEAP_DUMP_SEGMENT = 0x1C, HPROF_HEAP_DUMP_END = 0x2C, // field types HPROF_ARRAY_OBJECT = 0x01, HPROF_NORMAL_OBJECT = 0x02, HPROF_BOOLEAN = 0x04, HPROF_CHAR = 0x05, HPROF_FLOAT = 0x06, HPROF_DOUBLE = 0x07, HPROF_BYTE = 0x08, HPROF_SHORT = 0x09, HPROF_INT = 0x0A, HPROF_LONG = 0x0B, // data-dump sub-records HPROF_GC_ROOT_UNKNOWN = 0xFF, HPROF_GC_ROOT_JNI_GLOBAL = 0x01, HPROF_GC_ROOT_JNI_LOCAL = 0x02, HPROF_GC_ROOT_JAVA_FRAME = 0x03, HPROF_GC_ROOT_NATIVE_STACK = 0x04, HPROF_GC_ROOT_STICKY_CLASS = 0x05, HPROF_GC_ROOT_THREAD_BLOCK = 0x06, HPROF_GC_ROOT_MONITOR_USED = 0x07, HPROF_GC_ROOT_THREAD_OBJ = 0x08, HPROF_GC_CLASS_DUMP = 0x20, HPROF_GC_INSTANCE_DUMP = 0x21, HPROF_GC_OBJ_ARRAY_DUMP = 0x22, HPROF_GC_PRIM_ARRAY_DUMP = 0x23 }; // Default stack trace ID (used for dummy HPROF_TRACE record) enum { STACK_TRACE_ID = 1, INITIAL_CLASS_COUNT = 200 }; // Supports I/O operations for a dump // Base class for dump and parallel dump class AbstractDumpWriter : public CHeapObj { protected: enum { io_buffer_max_size = 1*M, dump_segment_header_size = 9 }; char* _buffer; // internal buffer size_t _size; size_t _pos; bool _in_dump_segment; // Are we currently in a dump segment? bool _is_huge_sub_record; // Are we writing a sub-record larger than the buffer size? DEBUG_ONLY(size_t _sub_record_left;) // The bytes not written for the current sub-record. DEBUG_ONLY(bool _sub_record_ended;) // True if we have called the end_sub_record(). char* buffer() const { return _buffer; } size_t buffer_size() const { return _size; } void set_position(size_t pos) { _pos = pos; } // Can be called if we have enough room in the buffer. void write_fast(const void* s, size_t len); // Returns true if we have enough room in the buffer for 'len' bytes. bool can_write_fast(size_t len); void write_address(address a); public: AbstractDumpWriter() : _buffer(nullptr), _size(io_buffer_max_size), _pos(0), _in_dump_segment(false) { } // Total number of bytes written to the disk virtual julong bytes_written() const = 0; // Return non-null if error occurred virtual char const* error() const = 0; size_t position() const { return _pos; } // writer functions virtual void write_raw(const void* s, size_t len); void write_u1(u1 x); void write_u2(u2 x); void write_u4(u4 x); void write_u8(u8 x); void write_objectID(oop o); void write_rootID(oop* p); void write_symbolID(Symbol* o); void write_classID(Klass* k); void write_id(u4 x); // Start a new sub-record. Starts a new heap dump segment if needed. void start_sub_record(u1 tag, u4 len); // Ends the current sub-record. void end_sub_record(); // Finishes the current dump segment if not already finished. void finish_dump_segment(); // Flush internal buffer to persistent storage virtual void flush() = 0; }; void AbstractDumpWriter::write_fast(const void* s, size_t len) { assert(!_in_dump_segment || (_sub_record_left >= len), "sub-record too large"); assert(buffer_size() - position() >= len, "Must fit"); DEBUG_ONLY(_sub_record_left -= len); memcpy(buffer() + position(), s, len); set_position(position() + len); } bool AbstractDumpWriter::can_write_fast(size_t len) { return buffer_size() - position() >= len; } // write raw bytes void AbstractDumpWriter::write_raw(const void* s, size_t len) { assert(!_in_dump_segment || (_sub_record_left >= len), "sub-record too large"); DEBUG_ONLY(_sub_record_left -= len); // flush buffer to make room. while (len > buffer_size() - position()) { assert(!_in_dump_segment || _is_huge_sub_record, "Cannot overflow in non-huge sub-record."); size_t to_write = buffer_size() - position(); memcpy(buffer() + position(), s, to_write); s = (void*) ((char*) s + to_write); len -= to_write; set_position(position() + to_write); flush(); } memcpy(buffer() + position(), s, len); set_position(position() + len); } // Makes sure we inline the fast write into the write_u* functions. This is a big speedup. #define WRITE_KNOWN_TYPE(p, len) do { if (can_write_fast((len))) write_fast((p), (len)); \ else write_raw((p), (len)); } while (0) void AbstractDumpWriter::write_u1(u1 x) { WRITE_KNOWN_TYPE(&x, 1); } void AbstractDumpWriter::write_u2(u2 x) { u2 v; Bytes::put_Java_u2((address)&v, x); WRITE_KNOWN_TYPE(&v, 2); } void AbstractDumpWriter::write_u4(u4 x) { u4 v; Bytes::put_Java_u4((address)&v, x); WRITE_KNOWN_TYPE(&v, 4); } void AbstractDumpWriter::write_u8(u8 x) { u8 v; Bytes::put_Java_u8((address)&v, x); WRITE_KNOWN_TYPE(&v, 8); } void AbstractDumpWriter::write_address(address a) { #ifdef _LP64 write_u8((u8)a); #else write_u4((u4)a); #endif } void AbstractDumpWriter::write_objectID(oop o) { write_address(cast_from_oop
(o)); } void AbstractDumpWriter::write_rootID(oop* p) { write_address((address)p); } void AbstractDumpWriter::write_symbolID(Symbol* s) { write_address((address)((uintptr_t)s)); } void AbstractDumpWriter::write_id(u4 x) { #ifdef _LP64 write_u8((u8) x); #else write_u4(x); #endif } // We use java mirror as the class ID void AbstractDumpWriter::write_classID(Klass* k) { write_objectID(k->java_mirror()); } void AbstractDumpWriter::finish_dump_segment() { if (_in_dump_segment) { assert(_sub_record_left == 0, "Last sub-record not written completely"); assert(_sub_record_ended, "sub-record must have ended"); // Fix up the dump segment length if we haven't written a huge sub-record last // (in which case the segment length was already set to the correct value initially). if (!_is_huge_sub_record) { assert(position() > dump_segment_header_size, "Dump segment should have some content"); Bytes::put_Java_u4((address) (buffer() + 5), (u4) (position() - dump_segment_header_size)); } else { // Finish process huge sub record // Set _is_huge_sub_record to false so the parallel dump writer can flush data to file. _is_huge_sub_record = false; } _in_dump_segment = false; flush(); } } void AbstractDumpWriter::start_sub_record(u1 tag, u4 len) { if (!_in_dump_segment) { if (position() > 0) { flush(); } assert(position() == 0 && buffer_size() > dump_segment_header_size, "Must be at the start"); write_u1(HPROF_HEAP_DUMP_SEGMENT); write_u4(0); // timestamp // Will be fixed up later if we add more sub-records. If this is a huge sub-record, // this is already the correct length, since we don't add more sub-records. write_u4(len); assert(Bytes::get_Java_u4((address)(buffer() + 5)) == len, "Inconsistent size!"); _in_dump_segment = true; _is_huge_sub_record = len > buffer_size() - dump_segment_header_size; } else if (_is_huge_sub_record || (len > buffer_size() - position())) { // This object will not fit in completely or the last sub-record was huge. // Finish the current segment and try again. finish_dump_segment(); start_sub_record(tag, len); return; } DEBUG_ONLY(_sub_record_left = len); DEBUG_ONLY(_sub_record_ended = false); write_u1(tag); } void AbstractDumpWriter::end_sub_record() { assert(_in_dump_segment, "must be in dump segment"); assert(_sub_record_left == 0, "sub-record not written completely"); assert(!_sub_record_ended, "Must not have ended yet"); DEBUG_ONLY(_sub_record_ended = true); } // Supports I/O operations for a dump class DumpWriter : public AbstractDumpWriter { private: FileWriter* _writer; AbstractCompressor* _compressor; size_t _bytes_written; char* _error; // Compression support char* _out_buffer; size_t _out_size; size_t _out_pos; char* _tmp_buffer; size_t _tmp_size; private: void do_compress(); public: DumpWriter(const char* path, bool overwrite, AbstractCompressor* compressor); ~DumpWriter(); julong bytes_written() const override { return (julong) _bytes_written; } char const* error() const override { return _error; } void set_error(const char* error) { _error = (char*)error; } bool has_error() const { return _error != nullptr; } const char* get_file_path() const { return _writer->get_file_path(); } AbstractCompressor* compressor() { return _compressor; } bool is_overwrite() const { return _writer->is_overwrite(); } void flush() override; private: // internals for DumpMerger friend class DumpMerger; void set_bytes_written(julong bytes_written) { _bytes_written = bytes_written; } int get_fd() const { return _writer->get_fd(); } void set_compressor(AbstractCompressor* p) { _compressor = p; } }; DumpWriter::DumpWriter(const char* path, bool overwrite, AbstractCompressor* compressor) : AbstractDumpWriter(), _writer(new (std::nothrow) FileWriter(path, overwrite)), _compressor(compressor), _bytes_written(0), _error(nullptr), _out_buffer(nullptr), _out_size(0), _out_pos(0), _tmp_buffer(nullptr), _tmp_size(0) { _error = (char*)_writer->open_writer(); if (_error == nullptr) { _buffer = (char*)os::malloc(io_buffer_max_size, mtInternal); if (compressor != nullptr) { _error = (char*)_compressor->init(io_buffer_max_size, &_out_size, &_tmp_size); if (_error == nullptr) { if (_out_size > 0) { _out_buffer = (char*)os::malloc(_out_size, mtInternal); } if (_tmp_size > 0) { _tmp_buffer = (char*)os::malloc(_tmp_size, mtInternal); } } } } // initialize internal buffer _pos = 0; _size = io_buffer_max_size; } DumpWriter::~DumpWriter(){ if (_buffer != nullptr) { os::free(_buffer); } if (_out_buffer != nullptr) { os::free(_out_buffer); } if (_tmp_buffer != nullptr) { os::free(_tmp_buffer); } if (_writer != nullptr) { delete _writer; } _bytes_written = -1; } // flush any buffered bytes to the file void DumpWriter::flush() { if (_pos <= 0) { return; } if (has_error()) { _pos = 0; return; } char* result = nullptr; if (_compressor == nullptr) { result = (char*)_writer->write_buf(_buffer, _pos); _bytes_written += _pos; } else { do_compress(); if (!has_error()) { result = (char*)_writer->write_buf(_out_buffer, _out_pos); _bytes_written += _out_pos; } } _pos = 0; // reset pos to make internal buffer available if (result != nullptr) { set_error(result); } } void DumpWriter::do_compress() { const char* msg = _compressor->compress(_buffer, _pos, _out_buffer, _out_size, _tmp_buffer, _tmp_size, &_out_pos); if (msg != nullptr) { set_error(msg); } } class DumperClassCacheTable; class DumperClassCacheTableEntry; // Support class with a collection of functions used when dumping the heap class DumperSupport : AllStatic { public: // write a header of the given type static void write_header(AbstractDumpWriter* writer, hprofTag tag, u4 len); // returns hprof tag for the given type signature static hprofTag sig2tag(Symbol* sig); // returns hprof tag for the given basic type static hprofTag type2tag(BasicType type); // Returns the size of the data to write. static u4 sig2size(Symbol* sig); // returns the size of the instance of the given class static u4 instance_size(InstanceKlass* ik, DumperClassCacheTableEntry* class_cache_entry = nullptr); // dump a jfloat static void dump_float(AbstractDumpWriter* writer, jfloat f); // dump a jdouble static void dump_double(AbstractDumpWriter* writer, jdouble d); // dumps the raw value of the given field static void dump_field_value(AbstractDumpWriter* writer, char type, oop obj, int offset); // returns the size of the static fields; also counts the static fields static u4 get_static_fields_size(InstanceKlass* ik, u2& field_count); // dumps static fields of the given class static void dump_static_fields(AbstractDumpWriter* writer, Klass* k); // dump the raw values of the instance fields of the given object static void dump_instance_fields(AbstractDumpWriter* writer, oop o, DumperClassCacheTableEntry* class_cache_entry); // get the count of the instance fields for a given class static u2 get_instance_fields_count(InstanceKlass* ik); // dumps the definition of the instance fields for a given class static void dump_instance_field_descriptors(AbstractDumpWriter* writer, Klass* k); // creates HPROF_GC_INSTANCE_DUMP record for the given object static void dump_instance(AbstractDumpWriter* writer, oop o, DumperClassCacheTable* class_cache); // creates HPROF_GC_CLASS_DUMP record for the given instance class static void dump_instance_class(AbstractDumpWriter* writer, Klass* k); // creates HPROF_GC_CLASS_DUMP record for a given array class static void dump_array_class(AbstractDumpWriter* writer, Klass* k); // creates HPROF_GC_OBJ_ARRAY_DUMP record for the given object array static void dump_object_array(AbstractDumpWriter* writer, objArrayOop array); // creates HPROF_GC_PRIM_ARRAY_DUMP record for the given type array static void dump_prim_array(AbstractDumpWriter* writer, typeArrayOop array); // create HPROF_FRAME record for the given method and bci static void dump_stack_frame(AbstractDumpWriter* writer, int frame_serial_num, int class_serial_num, Method* m, int bci); // check if we need to truncate an array static int calculate_array_max_length(AbstractDumpWriter* writer, arrayOop array, short header_size); // fixes up the current dump record and writes HPROF_HEAP_DUMP_END record static void end_of_dump(AbstractDumpWriter* writer); static oop mask_dormant_archived_object(oop o, oop ref_obj) { if (o != nullptr && o->klass()->java_mirror_no_keepalive() == nullptr) { // Ignore this object since the corresponding java mirror is not loaded. // Might be a dormant archive object. report_dormant_archived_object(o, ref_obj); return nullptr; } else { return o; } } static void report_dormant_archived_object(oop o, oop ref_obj) { if (log_is_enabled(Trace, aot, heap)) { ResourceMark rm; if (ref_obj != nullptr) { log_trace(aot, heap)("skipped dormant archived object " INTPTR_FORMAT " (%s) referenced by " INTPTR_FORMAT " (%s)", p2i(o), o->klass()->external_name(), p2i(ref_obj), ref_obj->klass()->external_name()); } else { log_trace(aot, heap)("skipped dormant archived object " INTPTR_FORMAT " (%s)", p2i(o), o->klass()->external_name()); } } } }; // Hash table of klasses to the klass metadata. This should greatly improve the // hash dumping performance. This hash table is supposed to be used by a single // thread only. // class DumperClassCacheTableEntry : public CHeapObj { friend class DumperClassCacheTable; private: GrowableArray _sigs_start; GrowableArray _offsets; u4 _instance_size; int _entries; public: DumperClassCacheTableEntry() : _instance_size(0), _entries(0) {}; int field_count() { return _entries; } char sig_start(int field_idx) { return _sigs_start.at(field_idx); } int offset(int field_idx) { return _offsets.at(field_idx); } u4 instance_size() { return _instance_size; } }; class DumperClassCacheTable { private: // ResourceHashtable SIZE is specified at compile time so we // use 1031 which is the first prime after 1024. static constexpr size_t TABLE_SIZE = 1031; // Maintain the cache for N classes. This limits memory footprint // impact, regardless of how many classes we have in the dump. // This also improves look up performance by keeping the statically // sized table from overloading. static constexpr int CACHE_TOP = 256; typedef ResourceHashtable PtrTable; PtrTable* _ptrs; // Single-slot cache to handle the major case of objects of the same // class back-to-back, e.g. from T[]. InstanceKlass* _last_ik; DumperClassCacheTableEntry* _last_entry; void unlink_all(PtrTable* table) { class CleanupEntry: StackObj { public: bool do_entry(InstanceKlass*& key, DumperClassCacheTableEntry*& entry) { delete entry; return true; } } cleanup; table->unlink(&cleanup); } public: DumperClassCacheTableEntry* lookup_or_create(InstanceKlass* ik) { if (_last_ik == ik) { return _last_entry; } DumperClassCacheTableEntry* entry; DumperClassCacheTableEntry** from_cache = _ptrs->get(ik); if (from_cache == nullptr) { entry = new DumperClassCacheTableEntry(); for (HierarchicalFieldStream fld(ik); !fld.done(); fld.next()) { if (!fld.access_flags().is_static()) { Symbol* sig = fld.signature(); entry->_sigs_start.push(sig->char_at(0)); entry->_offsets.push(fld.offset()); entry->_entries++; entry->_instance_size += DumperSupport::sig2size(sig); } } if (_ptrs->number_of_entries() >= CACHE_TOP) { // We do not track the individual hit rates for table entries. // Purge the entire table, and let the cache catch up with new // distribution. unlink_all(_ptrs); } _ptrs->put(ik, entry); } else { entry = *from_cache; } // Remember for single-slot cache. _last_ik = ik; _last_entry = entry; return entry; } DumperClassCacheTable() : _ptrs(new (mtServiceability) PtrTable), _last_ik(nullptr), _last_entry(nullptr) {} ~DumperClassCacheTable() { unlink_all(_ptrs); delete _ptrs; } }; // write a header of the given type void DumperSupport:: write_header(AbstractDumpWriter* writer, hprofTag tag, u4 len) { writer->write_u1(tag); writer->write_u4(0); // current ticks writer->write_u4(len); } // returns hprof tag for the given type signature hprofTag DumperSupport::sig2tag(Symbol* sig) { switch (sig->char_at(0)) { case JVM_SIGNATURE_CLASS : return HPROF_NORMAL_OBJECT; case JVM_SIGNATURE_ARRAY : return HPROF_NORMAL_OBJECT; case JVM_SIGNATURE_BYTE : return HPROF_BYTE; case JVM_SIGNATURE_CHAR : return HPROF_CHAR; case JVM_SIGNATURE_FLOAT : return HPROF_FLOAT; case JVM_SIGNATURE_DOUBLE : return HPROF_DOUBLE; case JVM_SIGNATURE_INT : return HPROF_INT; case JVM_SIGNATURE_LONG : return HPROF_LONG; case JVM_SIGNATURE_SHORT : return HPROF_SHORT; case JVM_SIGNATURE_BOOLEAN : return HPROF_BOOLEAN; default : ShouldNotReachHere(); /* to shut up compiler */ return HPROF_BYTE; } } hprofTag DumperSupport::type2tag(BasicType type) { switch (type) { case T_BYTE : return HPROF_BYTE; case T_CHAR : return HPROF_CHAR; case T_FLOAT : return HPROF_FLOAT; case T_DOUBLE : return HPROF_DOUBLE; case T_INT : return HPROF_INT; case T_LONG : return HPROF_LONG; case T_SHORT : return HPROF_SHORT; case T_BOOLEAN : return HPROF_BOOLEAN; default : ShouldNotReachHere(); /* to shut up compiler */ return HPROF_BYTE; } } u4 DumperSupport::sig2size(Symbol* sig) { switch (sig->char_at(0)) { case JVM_SIGNATURE_CLASS: case JVM_SIGNATURE_ARRAY: return sizeof(address); case JVM_SIGNATURE_BOOLEAN: case JVM_SIGNATURE_BYTE: return 1; case JVM_SIGNATURE_SHORT: case JVM_SIGNATURE_CHAR: return 2; case JVM_SIGNATURE_INT: case JVM_SIGNATURE_FLOAT: return 4; case JVM_SIGNATURE_LONG: case JVM_SIGNATURE_DOUBLE: return 8; default: ShouldNotReachHere(); /* to shut up compiler */ return 0; } } template T bit_cast(F from) { // replace with the real thing when we can use c++20 T to; static_assert(sizeof(to) == sizeof(from), "must be of the same size"); memcpy(&to, &from, sizeof(to)); return to; } // dump a jfloat void DumperSupport::dump_float(AbstractDumpWriter* writer, jfloat f) { if (g_isnan(f)) { writer->write_u4(0x7fc00000); // collapsing NaNs } else { writer->write_u4(bit_cast(f)); } } // dump a jdouble void DumperSupport::dump_double(AbstractDumpWriter* writer, jdouble d) { if (g_isnan(d)) { writer->write_u8(0x7ff80000ull << 32); // collapsing NaNs } else { writer->write_u8(bit_cast(d)); } } // dumps the raw value of the given field void DumperSupport::dump_field_value(AbstractDumpWriter* writer, char type, oop obj, int offset) { switch (type) { case JVM_SIGNATURE_CLASS : case JVM_SIGNATURE_ARRAY : { oop o = obj->obj_field_access(offset); o = mask_dormant_archived_object(o, obj); assert(oopDesc::is_oop_or_null(o), "Expected an oop or nullptr at " PTR_FORMAT, p2i(o)); writer->write_objectID(o); break; } case JVM_SIGNATURE_BYTE : { jbyte b = obj->byte_field(offset); writer->write_u1(b); break; } case JVM_SIGNATURE_CHAR : { jchar c = obj->char_field(offset); writer->write_u2(c); break; } case JVM_SIGNATURE_SHORT : { jshort s = obj->short_field(offset); writer->write_u2(s); break; } case JVM_SIGNATURE_FLOAT : { jfloat f = obj->float_field(offset); dump_float(writer, f); break; } case JVM_SIGNATURE_DOUBLE : { jdouble d = obj->double_field(offset); dump_double(writer, d); break; } case JVM_SIGNATURE_INT : { jint i = obj->int_field(offset); writer->write_u4(i); break; } case JVM_SIGNATURE_LONG : { jlong l = obj->long_field(offset); writer->write_u8(l); break; } case JVM_SIGNATURE_BOOLEAN : { jboolean b = obj->bool_field(offset); writer->write_u1(b); break; } default : { ShouldNotReachHere(); break; } } } // returns the size of the instance of the given class u4 DumperSupport::instance_size(InstanceKlass* ik, DumperClassCacheTableEntry* class_cache_entry) { if (class_cache_entry != nullptr) { return class_cache_entry->instance_size(); } else { u4 size = 0; for (HierarchicalFieldStream fld(ik); !fld.done(); fld.next()) { if (!fld.access_flags().is_static()) { size += sig2size(fld.signature()); } } return size; } } u4 DumperSupport::get_static_fields_size(InstanceKlass* ik, u2& field_count) { field_count = 0; u4 size = 0; for (JavaFieldStream fldc(ik); !fldc.done(); fldc.next()) { if (fldc.access_flags().is_static()) { field_count++; size += sig2size(fldc.signature()); } } // Add in resolved_references which is referenced by the cpCache // The resolved_references is an array per InstanceKlass holding the // strings and other oops resolved from the constant pool. oop resolved_references = ik->constants()->resolved_references_or_null(); if (resolved_references != nullptr) { field_count++; size += sizeof(address); // Add in the resolved_references of the used previous versions of the class // in the case of RedefineClasses InstanceKlass* prev = ik->previous_versions(); while (prev != nullptr && prev->constants()->resolved_references_or_null() != nullptr) { field_count++; size += sizeof(address); prev = prev->previous_versions(); } } // Also provide a pointer to the init_lock if present, so there aren't unreferenced int[0] // arrays. oop init_lock = ik->init_lock(); if (init_lock != nullptr) { field_count++; size += sizeof(address); } // We write the value itself plus a name and a one byte type tag per field. return checked_cast(size + field_count * (sizeof(address) + 1)); } // dumps static fields of the given class void DumperSupport::dump_static_fields(AbstractDumpWriter* writer, Klass* k) { InstanceKlass* ik = InstanceKlass::cast(k); // dump the field descriptors and raw values for (JavaFieldStream fld(ik); !fld.done(); fld.next()) { if (fld.access_flags().is_static()) { Symbol* sig = fld.signature(); writer->write_symbolID(fld.name()); // name writer->write_u1(sig2tag(sig)); // type // value dump_field_value(writer, sig->char_at(0), ik->java_mirror(), fld.offset()); } } // Add resolved_references for each class that has them oop resolved_references = ik->constants()->resolved_references_or_null(); if (resolved_references != nullptr) { writer->write_symbolID(vmSymbols::resolved_references_name()); // name writer->write_u1(sig2tag(vmSymbols::object_array_signature())); // type writer->write_objectID(resolved_references); // Also write any previous versions InstanceKlass* prev = ik->previous_versions(); while (prev != nullptr && prev->constants()->resolved_references_or_null() != nullptr) { writer->write_symbolID(vmSymbols::resolved_references_name()); // name writer->write_u1(sig2tag(vmSymbols::object_array_signature())); // type writer->write_objectID(prev->constants()->resolved_references()); prev = prev->previous_versions(); } } // Add init lock to the end if the class is not yet initialized oop init_lock = ik->init_lock(); if (init_lock != nullptr) { writer->write_symbolID(vmSymbols::init_lock_name()); // name writer->write_u1(sig2tag(vmSymbols::int_array_signature())); // type writer->write_objectID(init_lock); } } // dump the raw values of the instance fields of the given object void DumperSupport::dump_instance_fields(AbstractDumpWriter* writer, oop o, DumperClassCacheTableEntry* class_cache_entry) { assert(class_cache_entry != nullptr, "Pre-condition: must be provided"); for (int idx = 0; idx < class_cache_entry->field_count(); idx++) { dump_field_value(writer, class_cache_entry->sig_start(idx), o, class_cache_entry->offset(idx)); } } // dumps the definition of the instance fields for a given class u2 DumperSupport::get_instance_fields_count(InstanceKlass* ik) { u2 field_count = 0; for (JavaFieldStream fldc(ik); !fldc.done(); fldc.next()) { if (!fldc.access_flags().is_static()) field_count++; } return field_count; } // dumps the definition of the instance fields for a given class void DumperSupport::dump_instance_field_descriptors(AbstractDumpWriter* writer, Klass* k) { InstanceKlass* ik = InstanceKlass::cast(k); // dump the field descriptors for (JavaFieldStream fld(ik); !fld.done(); fld.next()) { if (!fld.access_flags().is_static()) { Symbol* sig = fld.signature(); writer->write_symbolID(fld.name()); // name writer->write_u1(sig2tag(sig)); // type } } } // creates HPROF_GC_INSTANCE_DUMP record for the given object void DumperSupport::dump_instance(AbstractDumpWriter* writer, oop o, DumperClassCacheTable* class_cache) { InstanceKlass* ik = InstanceKlass::cast(o->klass()); DumperClassCacheTableEntry* cache_entry = class_cache->lookup_or_create(ik); u4 is = instance_size(ik, cache_entry); u4 size = 1 + sizeof(address) + 4 + sizeof(address) + 4 + is; writer->start_sub_record(HPROF_GC_INSTANCE_DUMP, size); writer->write_objectID(o); writer->write_u4(STACK_TRACE_ID); // class ID writer->write_classID(ik); // number of bytes that follow writer->write_u4(is); // field values dump_instance_fields(writer, o, cache_entry); writer->end_sub_record(); } // creates HPROF_GC_CLASS_DUMP record for the given instance class void DumperSupport::dump_instance_class(AbstractDumpWriter* writer, Klass* k) { InstanceKlass* ik = InstanceKlass::cast(k); // We can safepoint and do a heap dump at a point where we have a Klass, // but no java mirror class has been setup for it. So we need to check // that the class is at least loaded, to avoid crash from a null mirror. if (!ik->is_loaded()) { return; } u2 static_fields_count = 0; u4 static_size = get_static_fields_size(ik, static_fields_count); u2 instance_fields_count = get_instance_fields_count(ik); u4 instance_fields_size = instance_fields_count * (sizeof(address) + 1); u4 size = checked_cast(1 + sizeof(address) + 4 + 6 * sizeof(address) + 4 + 2 + 2 + static_size + 2 + instance_fields_size); writer->start_sub_record(HPROF_GC_CLASS_DUMP, size); // class ID writer->write_classID(ik); writer->write_u4(STACK_TRACE_ID); // super class ID InstanceKlass* java_super = ik->java_super(); if (java_super == nullptr) { writer->write_objectID(oop(nullptr)); } else { writer->write_classID(java_super); } writer->write_objectID(ik->class_loader()); writer->write_objectID(ik->signers()); writer->write_objectID(ik->protection_domain()); // reserved writer->write_objectID(oop(nullptr)); writer->write_objectID(oop(nullptr)); // instance size writer->write_u4(DumperSupport::instance_size(ik)); // size of constant pool - ignored by HAT 1.1 writer->write_u2(0); // static fields writer->write_u2(static_fields_count); dump_static_fields(writer, ik); // description of instance fields writer->write_u2(instance_fields_count); dump_instance_field_descriptors(writer, ik); writer->end_sub_record(); } // creates HPROF_GC_CLASS_DUMP record for the given array class void DumperSupport::dump_array_class(AbstractDumpWriter* writer, Klass* k) { InstanceKlass* ik = nullptr; // bottom class for object arrays, null for primitive type arrays if (k->is_objArray_klass()) { Klass *bk = ObjArrayKlass::cast(k)->bottom_klass(); assert(bk != nullptr, "checking"); if (bk->is_instance_klass()) { ik = InstanceKlass::cast(bk); } } u4 size = 1 + sizeof(address) + 4 + 6 * sizeof(address) + 4 + 2 + 2 + 2; writer->start_sub_record(HPROF_GC_CLASS_DUMP, size); writer->write_classID(k); writer->write_u4(STACK_TRACE_ID); // super class of array classes is java.lang.Object InstanceKlass* java_super = k->java_super(); assert(java_super != nullptr, "checking"); writer->write_classID(java_super); writer->write_objectID(ik == nullptr ? oop(nullptr) : ik->class_loader()); writer->write_objectID(ik == nullptr ? oop(nullptr) : ik->signers()); writer->write_objectID(ik == nullptr ? oop(nullptr) : ik->protection_domain()); writer->write_objectID(oop(nullptr)); // reserved writer->write_objectID(oop(nullptr)); writer->write_u4(0); // instance size writer->write_u2(0); // constant pool writer->write_u2(0); // static fields writer->write_u2(0); // instance fields writer->end_sub_record(); } // Hprof uses an u4 as record length field, // which means we need to truncate arrays that are too long. int DumperSupport::calculate_array_max_length(AbstractDumpWriter* writer, arrayOop array, short header_size) { BasicType type = ArrayKlass::cast(array->klass())->element_type(); assert(type >= T_BOOLEAN && type <= T_OBJECT, "invalid array element type"); int length = array->length(); int type_size; if (type == T_OBJECT) { type_size = sizeof(address); } else { type_size = type2aelembytes(type); } size_t length_in_bytes = (size_t)length * type_size; uint max_bytes = max_juint - header_size; if (length_in_bytes > max_bytes) { length = max_bytes / type_size; length_in_bytes = (size_t)length * type_size; warning("cannot dump array of type %s[] with length %d; truncating to length %d", type2name_tab[type], array->length(), length); } return length; } // creates HPROF_GC_OBJ_ARRAY_DUMP record for the given object array void DumperSupport::dump_object_array(AbstractDumpWriter* writer, objArrayOop array) { // sizeof(u1) + 2 * sizeof(u4) + sizeof(objectID) + sizeof(classID) short header_size = 1 + 2 * 4 + 2 * sizeof(address); int length = calculate_array_max_length(writer, array, header_size); u4 size = checked_cast(header_size + length * sizeof(address)); writer->start_sub_record(HPROF_GC_OBJ_ARRAY_DUMP, size); writer->write_objectID(array); writer->write_u4(STACK_TRACE_ID); writer->write_u4(length); // array class ID writer->write_classID(array->klass()); // [id]* elements for (int index = 0; index < length; index++) { oop o = array->obj_at(index); o = mask_dormant_archived_object(o, array); writer->write_objectID(o); } writer->end_sub_record(); } #define WRITE_ARRAY(Array, Type, Size, Length) \ for (int i = 0; i < Length; i++) { writer->write_##Size((Size)Array->Type##_at(i)); } // creates HPROF_GC_PRIM_ARRAY_DUMP record for the given type array void DumperSupport::dump_prim_array(AbstractDumpWriter* writer, typeArrayOop array) { BasicType type = TypeArrayKlass::cast(array->klass())->element_type(); // 2 * sizeof(u1) + 2 * sizeof(u4) + sizeof(objectID) short header_size = 2 * 1 + 2 * 4 + sizeof(address); int length = calculate_array_max_length(writer, array, header_size); int type_size = type2aelembytes(type); u4 length_in_bytes = (u4)length * type_size; u4 size = header_size + length_in_bytes; writer->start_sub_record(HPROF_GC_PRIM_ARRAY_DUMP, size); writer->write_objectID(array); writer->write_u4(STACK_TRACE_ID); writer->write_u4(length); writer->write_u1(type2tag(type)); // nothing to copy if (length == 0) { writer->end_sub_record(); return; } // If the byte ordering is big endian then we can copy most types directly switch (type) { case T_INT : { if (Endian::is_Java_byte_ordering_different()) { WRITE_ARRAY(array, int, u4, length); } else { writer->write_raw(array->int_at_addr(0), length_in_bytes); } break; } case T_BYTE : { writer->write_raw(array->byte_at_addr(0), length_in_bytes); break; } case T_CHAR : { if (Endian::is_Java_byte_ordering_different()) { WRITE_ARRAY(array, char, u2, length); } else { writer->write_raw(array->char_at_addr(0), length_in_bytes); } break; } case T_SHORT : { if (Endian::is_Java_byte_ordering_different()) { WRITE_ARRAY(array, short, u2, length); } else { writer->write_raw(array->short_at_addr(0), length_in_bytes); } break; } case T_BOOLEAN : { if (Endian::is_Java_byte_ordering_different()) { WRITE_ARRAY(array, bool, u1, length); } else { writer->write_raw(array->bool_at_addr(0), length_in_bytes); } break; } case T_LONG : { if (Endian::is_Java_byte_ordering_different()) { WRITE_ARRAY(array, long, u8, length); } else { writer->write_raw(array->long_at_addr(0), length_in_bytes); } break; } // handle float/doubles in a special value to ensure than NaNs are // written correctly. TO DO: Check if we can avoid this on processors that // use IEEE 754. case T_FLOAT : { for (int i = 0; i < length; i++) { dump_float(writer, array->float_at(i)); } break; } case T_DOUBLE : { for (int i = 0; i < length; i++) { dump_double(writer, array->double_at(i)); } break; } default : ShouldNotReachHere(); } writer->end_sub_record(); } // create a HPROF_FRAME record of the given Method* and bci void DumperSupport::dump_stack_frame(AbstractDumpWriter* writer, int frame_serial_num, int class_serial_num, Method* m, int bci) { int line_number; if (m->is_native()) { line_number = -3; // native frame } else { line_number = m->line_number_from_bci(bci); } write_header(writer, HPROF_FRAME, 4*oopSize + 2*sizeof(u4)); writer->write_id(frame_serial_num); // frame serial number writer->write_symbolID(m->name()); // method's name writer->write_symbolID(m->signature()); // method's signature assert(m->method_holder()->is_instance_klass(), "not InstanceKlass"); writer->write_symbolID(m->method_holder()->source_file_name()); // source file name writer->write_u4(class_serial_num); // class serial number writer->write_u4((u4) line_number); // line number } // Support class used to generate HPROF_UTF8 records from the entries in the // SymbolTable. class SymbolTableDumper : public SymbolClosure { private: AbstractDumpWriter* _writer; AbstractDumpWriter* writer() const { return _writer; } public: SymbolTableDumper(AbstractDumpWriter* writer) { _writer = writer; } void do_symbol(Symbol** p); }; void SymbolTableDumper::do_symbol(Symbol** p) { ResourceMark rm; Symbol* sym = *p; int len = sym->utf8_length(); if (len > 0) { char* s = sym->as_utf8(); DumperSupport::write_header(writer(), HPROF_UTF8, oopSize + len); writer()->write_symbolID(sym); writer()->write_raw(s, len); } } // Support class used to generate HPROF_GC_CLASS_DUMP records class ClassDumper : public KlassClosure { private: AbstractDumpWriter* _writer; AbstractDumpWriter* writer() const { return _writer; } public: ClassDumper(AbstractDumpWriter* writer) : _writer(writer) {} void do_klass(Klass* k) { if (k->is_instance_klass()) { DumperSupport::dump_instance_class(writer(), k); } else { DumperSupport::dump_array_class(writer(), k); } } }; // Support class used to generate HPROF_LOAD_CLASS records class LoadedClassDumper : public LockedClassesDo { private: AbstractDumpWriter* _writer; GrowableArray* _klass_map; u4 _class_serial_num; AbstractDumpWriter* writer() const { return _writer; } void add_class_serial_number(Klass* k, int serial_num) { _klass_map->at_put_grow(serial_num, k); } public: LoadedClassDumper(AbstractDumpWriter* writer, GrowableArray* klass_map) : _writer(writer), _klass_map(klass_map), _class_serial_num(0) {} void do_klass(Klass* k) { // len of HPROF_LOAD_CLASS record u4 remaining = 2 * oopSize + 2 * sizeof(u4); DumperSupport::write_header(writer(), HPROF_LOAD_CLASS, remaining); // class serial number is just a number writer()->write_u4(++_class_serial_num); // class ID writer()->write_classID(k); // add the Klass* and class serial number pair add_class_serial_number(k, _class_serial_num); writer()->write_u4(STACK_TRACE_ID); // class name ID Symbol* name = k->name(); writer()->write_symbolID(name); } }; // Support class used to generate HPROF_GC_ROOT_JNI_LOCAL records class JNILocalsDumper : public OopClosure { private: AbstractDumpWriter* _writer; u4 _thread_serial_num; int _frame_num; AbstractDumpWriter* writer() const { return _writer; } public: JNILocalsDumper(AbstractDumpWriter* writer, u4 thread_serial_num) { _writer = writer; _thread_serial_num = thread_serial_num; _frame_num = -1; // default - empty stack } void set_frame_number(int n) { _frame_num = n; } void do_oop(oop* obj_p); void do_oop(narrowOop* obj_p) { ShouldNotReachHere(); } }; void JNILocalsDumper::do_oop(oop* obj_p) { // ignore null handles oop o = *obj_p; if (o != nullptr) { u4 size = 1 + sizeof(address) + 4 + 4; writer()->start_sub_record(HPROF_GC_ROOT_JNI_LOCAL, size); writer()->write_objectID(o); writer()->write_u4(_thread_serial_num); writer()->write_u4((u4)_frame_num); writer()->end_sub_record(); } } // Support class used to generate HPROF_GC_ROOT_JNI_GLOBAL records class JNIGlobalsDumper : public OopClosure { private: AbstractDumpWriter* _writer; AbstractDumpWriter* writer() const { return _writer; } public: JNIGlobalsDumper(AbstractDumpWriter* writer) { _writer = writer; } void do_oop(oop* obj_p); void do_oop(narrowOop* obj_p) { ShouldNotReachHere(); } }; void JNIGlobalsDumper::do_oop(oop* obj_p) { oop o = NativeAccess::oop_load(obj_p); // ignore these if (o == nullptr) return; // we ignore global ref to symbols and other internal objects if (o->is_instance() || o->is_objArray() || o->is_typeArray()) { u4 size = 1 + 2 * sizeof(address); writer()->start_sub_record(HPROF_GC_ROOT_JNI_GLOBAL, size); writer()->write_objectID(o); writer()->write_rootID(obj_p); // global ref ID writer()->end_sub_record(); } }; // Support class used to generate HPROF_GC_ROOT_STICKY_CLASS records class StickyClassDumper : public KlassClosure { private: AbstractDumpWriter* _writer; AbstractDumpWriter* writer() const { return _writer; } public: StickyClassDumper(AbstractDumpWriter* writer) { _writer = writer; } void do_klass(Klass* k) { if (k->is_instance_klass()) { InstanceKlass* ik = InstanceKlass::cast(k); u4 size = 1 + sizeof(address); writer()->start_sub_record(HPROF_GC_ROOT_STICKY_CLASS, size); writer()->write_classID(ik); writer()->end_sub_record(); } } }; // Support class used to generate HPROF_GC_ROOT_JAVA_FRAME records. class JavaStackRefDumper : public StackObj { private: AbstractDumpWriter* _writer; u4 _thread_serial_num; int _frame_num; AbstractDumpWriter* writer() const { return _writer; } public: JavaStackRefDumper(AbstractDumpWriter* writer, u4 thread_serial_num) : _writer(writer), _thread_serial_num(thread_serial_num), _frame_num(-1) // default - empty stack { } void set_frame_number(int n) { _frame_num = n; } void dump_java_stack_refs(StackValueCollection* values); }; void JavaStackRefDumper::dump_java_stack_refs(StackValueCollection* values) { for (int index = 0; index < values->size(); index++) { if (values->at(index)->type() == T_OBJECT) { oop o = values->obj_at(index)(); if (o != nullptr) { u4 size = 1 + sizeof(address) + 4 + 4; writer()->start_sub_record(HPROF_GC_ROOT_JAVA_FRAME, size); writer()->write_objectID(o); writer()->write_u4(_thread_serial_num); writer()->write_u4((u4)_frame_num); writer()->end_sub_record(); } } } } // Class to collect, store and dump thread-related data: // - HPROF_TRACE and HPROF_FRAME records; // - HPROF_GC_ROOT_THREAD_OBJ/HPROF_GC_ROOT_JAVA_FRAME/HPROF_GC_ROOT_JNI_LOCAL subrecords. class ThreadDumper : public CHeapObj { public: enum class ThreadType { Platform, MountedVirtual, UnmountedVirtual }; private: ThreadType _thread_type; JavaThread* _java_thread; oop _thread_oop; GrowableArray* _frames; // non-null if the thread is OOM thread Method* _oome_constructor; int _thread_serial_num; int _start_frame_serial_num; vframe* get_top_frame() const; public: static bool should_dump_pthread(JavaThread* thread) { return thread->threadObj() != nullptr && !thread->is_exiting() && !thread->is_hidden_from_external_view(); } static bool should_dump_vthread(oop vt) { return java_lang_VirtualThread::state(vt) != java_lang_VirtualThread::NEW && java_lang_VirtualThread::state(vt) != java_lang_VirtualThread::TERMINATED; } static bool is_vthread_mounted(oop vt) { // The code should be consistent with the "mounted virtual thread" case // (VM_HeapDumper::dump_stack_traces(), ThreadDumper::get_top_frame()). // I.e. virtual thread is mounted if its carrierThread is not null // and is_vthread_mounted() for the carrier thread returns true. oop carrier_thread = java_lang_VirtualThread::carrier_thread(vt); if (carrier_thread == nullptr) { return false; } JavaThread* java_thread = java_lang_Thread::thread(carrier_thread); return java_thread->is_vthread_mounted(); } ThreadDumper(ThreadType thread_type, JavaThread* java_thread, oop thread_oop); ~ThreadDumper() { for (int index = 0; index < _frames->length(); index++) { delete _frames->at(index); } delete _frames; } // affects frame_count void add_oom_frame(Method* oome_constructor) { assert(_start_frame_serial_num == 0, "add_oom_frame cannot be called after init_serial_nums"); _oome_constructor = oome_constructor; } void init_serial_nums(volatile int* thread_counter, volatile int* frame_counter) { assert(_start_frame_serial_num == 0, "already initialized"); _thread_serial_num = Atomic::fetch_then_add(thread_counter, 1); _start_frame_serial_num = Atomic::fetch_then_add(frame_counter, frame_count()); } bool oom_thread() const { return _oome_constructor != nullptr; } int frame_count() const { return _frames->length() + (oom_thread() ? 1 : 0); } u4 thread_serial_num() const { return (u4)_thread_serial_num; } u4 stack_trace_serial_num() const { return (u4)(_thread_serial_num + STACK_TRACE_ID); } // writes HPROF_TRACE and HPROF_FRAME records // returns number of dumped frames void dump_stack_traces(AbstractDumpWriter* writer, GrowableArray* klass_map); // writes HPROF_GC_ROOT_THREAD_OBJ subrecord void dump_thread_obj(AbstractDumpWriter* writer); // Walk the stack of the thread. // Dumps a HPROF_GC_ROOT_JAVA_FRAME subrecord for each local // Dumps a HPROF_GC_ROOT_JNI_LOCAL subrecord for each JNI local void dump_stack_refs(AbstractDumpWriter* writer); }; ThreadDumper::ThreadDumper(ThreadType thread_type, JavaThread* java_thread, oop thread_oop) : _thread_type(thread_type), _java_thread(java_thread), _thread_oop(thread_oop), _oome_constructor(nullptr), _thread_serial_num(0), _start_frame_serial_num(0) { // sanity checks if (_thread_type == ThreadType::UnmountedVirtual) { assert(_java_thread == nullptr, "sanity"); assert(_thread_oop != nullptr, "sanity"); } else { assert(_java_thread != nullptr, "sanity"); assert(_thread_oop != nullptr, "sanity"); } _frames = new (mtServiceability) GrowableArray(10, mtServiceability); bool stop_at_vthread_entry = _thread_type == ThreadType::MountedVirtual; // vframes are resource allocated Thread* current_thread = Thread::current(); ResourceMark rm(current_thread); HandleMark hm(current_thread); for (vframe* vf = get_top_frame(); vf != nullptr; vf = vf->sender()) { if (stop_at_vthread_entry && vf->is_vthread_entry()) { break; } if (vf->is_java_frame()) { javaVFrame* jvf = javaVFrame::cast(vf); _frames->append(new StackFrameInfo(jvf, false)); } else { // ignore non-Java frames } } } void ThreadDumper::dump_stack_traces(AbstractDumpWriter* writer, GrowableArray* klass_map) { assert(_thread_serial_num != 0 && _start_frame_serial_num != 0, "serial_nums are not initialized"); // write HPROF_FRAME records for this thread's stack trace int depth = _frames->length(); int frame_serial_num = _start_frame_serial_num; if (oom_thread()) { // OOM thread // write fake frame that makes it look like the thread, which caused OOME, // is in the OutOfMemoryError zero-parameter constructor int oome_serial_num = klass_map->find(_oome_constructor->method_holder()); // the class serial number starts from 1 assert(oome_serial_num > 0, "OutOfMemoryError class not found"); DumperSupport::dump_stack_frame(writer, ++frame_serial_num, oome_serial_num, _oome_constructor, 0); depth++; } for (int j = 0; j < _frames->length(); j++) { StackFrameInfo* frame = _frames->at(j); Method* m = frame->method(); int class_serial_num = klass_map->find(m->method_holder()); // the class serial number starts from 1 assert(class_serial_num > 0, "class not found"); DumperSupport::dump_stack_frame(writer, ++frame_serial_num, class_serial_num, m, frame->bci()); } // write HPROF_TRACE record for the thread DumperSupport::write_header(writer, HPROF_TRACE, checked_cast(3 * sizeof(u4) + depth * oopSize)); writer->write_u4(stack_trace_serial_num()); // stack trace serial number writer->write_u4(thread_serial_num()); // thread serial number writer->write_u4((u4)depth); // frame count (including oom frame) for (int j = 1; j <= depth; j++) { writer->write_id(_start_frame_serial_num + j); } } void ThreadDumper::dump_thread_obj(AbstractDumpWriter * writer) { assert(_thread_serial_num != 0 && _start_frame_serial_num != 0, "serial_num is not initialized"); u4 size = 1 + sizeof(address) + 4 + 4; writer->start_sub_record(HPROF_GC_ROOT_THREAD_OBJ, size); writer->write_objectID(_thread_oop); writer->write_u4(thread_serial_num()); // thread serial number writer->write_u4(stack_trace_serial_num()); // stack trace serial number writer->end_sub_record(); } void ThreadDumper::dump_stack_refs(AbstractDumpWriter * writer) { assert(_thread_serial_num != 0 && _start_frame_serial_num != 0, "serial_num is not initialized"); JNILocalsDumper blk(writer, thread_serial_num()); if (_thread_type == ThreadType::Platform) { if (!_java_thread->has_last_Java_frame()) { // no last java frame but there may be JNI locals _java_thread->active_handles()->oops_do(&blk); return; } } JavaStackRefDumper java_ref_dumper(writer, thread_serial_num()); // vframes are resource allocated Thread* current_thread = Thread::current(); ResourceMark rm(current_thread); HandleMark hm(current_thread); bool stopAtVthreadEntry = _thread_type == ThreadType::MountedVirtual; frame* last_entry_frame = nullptr; bool is_top_frame = true; int depth = 0; if (oom_thread()) { depth++; } for (vframe* vf = get_top_frame(); vf != nullptr; vf = vf->sender()) { if (stopAtVthreadEntry && vf->is_vthread_entry()) { break; } if (vf->is_java_frame()) { javaVFrame* jvf = javaVFrame::cast(vf); if (!(jvf->method()->is_native())) { java_ref_dumper.set_frame_number(depth); java_ref_dumper.dump_java_stack_refs(jvf->locals()); java_ref_dumper.dump_java_stack_refs(jvf->expressions()); } else { // native frame blk.set_frame_number(depth); if (is_top_frame) { // JNI locals for the top frame if mounted assert(_java_thread != nullptr || jvf->method()->is_synchronized() || jvf->method()->is_object_wait0(), "impossible for unmounted vthread"); if (_java_thread != nullptr) { _java_thread->active_handles()->oops_do(&blk); } } else { if (last_entry_frame != nullptr) { // JNI locals for the entry frame assert(last_entry_frame->is_entry_frame(), "checking"); last_entry_frame->entry_frame_call_wrapper()->handles()->oops_do(&blk); } } } last_entry_frame = nullptr; // increment only for Java frames depth++; } else { // externalVFrame - for an entry frame then we report the JNI locals // when we find the corresponding javaVFrame frame* fr = vf->frame_pointer(); assert(fr != nullptr, "sanity check"); if (fr->is_entry_frame()) { last_entry_frame = fr; } } is_top_frame = false; } assert(depth == frame_count(), "total number of Java frames not matched"); } vframe* ThreadDumper::get_top_frame() const { if (_thread_type == ThreadType::UnmountedVirtual) { ContinuationWrapper cont(java_lang_VirtualThread::continuation(_thread_oop)); if (cont.is_empty()) { return nullptr; } assert(!cont.is_mounted(), "sanity check"); stackChunkOop chunk = cont.last_nonempty_chunk(); if (chunk == nullptr || chunk->is_empty()) { return nullptr; } RegisterMap reg_map(cont.continuation(), RegisterMap::UpdateMap::include); frame fr = chunk->top_frame(®_map); vframe* vf = vframe::new_vframe(&fr, ®_map, nullptr); // don't need JavaThread return vf; } RegisterMap reg_map(_java_thread, RegisterMap::UpdateMap::include, RegisterMap::ProcessFrames::include, RegisterMap::WalkContinuation::skip); switch (_thread_type) { case ThreadType::Platform: if (!_java_thread->has_last_Java_frame()) { return nullptr; } return _java_thread->is_vthread_mounted() ? _java_thread->carrier_last_java_vframe(®_map) : _java_thread->platform_thread_last_java_vframe(®_map); case ThreadType::MountedVirtual: return _java_thread->last_java_vframe(®_map); default: // make compilers happy break; } ShouldNotReachHere(); return nullptr; } // Callback to dump thread-related data for unmounted virtual threads; // implemented by VM_HeapDumper. class UnmountedVThreadDumper { public: virtual void dump_vthread(oop vt, AbstractDumpWriter* segment_writer) = 0; }; // Support class used when iterating over the heap. class HeapObjectDumper : public ObjectClosure { private: AbstractDumpWriter* _writer; AbstractDumpWriter* writer() { return _writer; } UnmountedVThreadDumper* _vthread_dumper; DumperClassCacheTable _class_cache; public: HeapObjectDumper(AbstractDumpWriter* writer, UnmountedVThreadDumper* vthread_dumper) : _writer(writer), _vthread_dumper(vthread_dumper) {} // called for each object in the heap void do_object(oop o); }; void HeapObjectDumper::do_object(oop o) { // skip classes as these emitted as HPROF_GC_CLASS_DUMP records if (o->klass() == vmClasses::Class_klass()) { if (!java_lang_Class::is_primitive(o)) { return; } } if (DumperSupport::mask_dormant_archived_object(o, nullptr) == nullptr) { return; } if (o->is_instance()) { // create a HPROF_GC_INSTANCE record for each object DumperSupport::dump_instance(writer(), o, &_class_cache); // If we encounter an unmounted virtual thread it needs to be dumped explicitly // (mounted virtual threads are dumped with their carriers). if (java_lang_VirtualThread::is_instance(o) && ThreadDumper::should_dump_vthread(o) && !ThreadDumper::is_vthread_mounted(o)) { _vthread_dumper->dump_vthread(o, writer()); } } else if (o->is_objArray()) { // create a HPROF_GC_OBJ_ARRAY_DUMP record for each object array DumperSupport::dump_object_array(writer(), objArrayOop(o)); } else if (o->is_typeArray()) { // create a HPROF_GC_PRIM_ARRAY_DUMP record for each type array DumperSupport::dump_prim_array(writer(), typeArrayOop(o)); } } // The dumper controller for parallel heap dump class DumperController : public CHeapObj { private: Monitor* _lock; Mutex* _global_writer_lock; const uint _dumper_number; uint _complete_number; bool _started; // VM dumper started and acquired global writer lock public: DumperController(uint number) : // _lock and _global_writer_lock are used for synchronization between GC worker threads inside safepoint, // so we lock with _no_safepoint_check_flag. // signal_start() acquires _lock when global writer is locked, // its rank must be less than _global_writer_lock rank. _lock(new (std::nothrow) PaddedMonitor(Mutex::nosafepoint - 1, "DumperController_lock")), _global_writer_lock(new (std::nothrow) Mutex(Mutex::nosafepoint, "DumpWriter_lock")), _dumper_number(number), _complete_number(0), _started(false) {} ~DumperController() { delete _lock; delete _global_writer_lock; } // parallel (non VM) dumpers must wait until VM dumper acquires global writer lock void wait_for_start_signal() { MonitorLocker ml(_lock, Mutex::_no_safepoint_check_flag); while (_started == false) { ml.wait(); } } void signal_start() { MonitorLocker ml(_lock, Mutex::_no_safepoint_check_flag); _started = true; ml.notify_all(); } void lock_global_writer() { _global_writer_lock->lock_without_safepoint_check(); } void unlock_global_writer() { _global_writer_lock->unlock(); } void dumper_complete(DumpWriter* local_writer, DumpWriter* global_writer) { MonitorLocker ml(_lock, Mutex::_no_safepoint_check_flag); _complete_number++; // propagate local error to global if any if (local_writer->has_error()) { global_writer->set_error(local_writer->error()); } ml.notify(); } void wait_all_dumpers_complete() { MonitorLocker ml(_lock, Mutex::_no_safepoint_check_flag); while (_complete_number != _dumper_number) { ml.wait(); } } }; // DumpMerger merges separate dump files into a complete one class DumpMerger : public StackObj { private: DumpWriter* _writer; const char* _path; bool _has_error; int _dump_seq; private: void merge_file(const char* path); void merge_done(); void set_error(const char* msg); public: DumpMerger(const char* path, DumpWriter* writer, int dump_seq) : _writer(writer), _path(path), _has_error(_writer->has_error()), _dump_seq(dump_seq) {} void do_merge(); // returns path for the parallel DumpWriter (resource allocated) static char* get_writer_path(const char* base_path, int seq); }; char* DumpMerger::get_writer_path(const char* base_path, int seq) { // approximate required buffer size size_t buf_size = strlen(base_path) + 2 // ".p" + 10 // number (that's enough for 2^32 parallel dumpers) + 1; // '\0' char* path = NEW_RESOURCE_ARRAY(char, buf_size); memset(path, 0, buf_size); os::snprintf(path, buf_size, "%s.p%d", base_path, seq); return path; } void DumpMerger::merge_done() { // Writes the HPROF_HEAP_DUMP_END record. if (!_has_error) { DumperSupport::end_of_dump(_writer); _writer->flush(); } _dump_seq = 0; //reset } void DumpMerger::set_error(const char* msg) { assert(msg != nullptr, "sanity check"); log_error(heapdump)("%s (file: %s)", msg, _path); _writer->set_error(msg); _has_error = true; } #ifdef LINUX // Merge segmented heap files via sendfile, it's more efficient than the // read+write combination, which would require transferring data to and from // user space. void DumpMerger::merge_file(const char* path) { TraceTime timer("Merge segmented heap file directly", TRACETIME_LOG(Info, heapdump)); int segment_fd = os::open(path, O_RDONLY, 0); if (segment_fd == -1) { set_error("Can not open segmented heap file during merging"); return; } struct stat st; if (os::stat(path, &st) != 0) { ::close(segment_fd); set_error("Can not get segmented heap file size during merging"); return; } // A successful call to sendfile may write fewer bytes than requested; the // caller should be prepared to retry the call if there were unsent bytes. jlong offset = 0; while (offset < st.st_size) { int ret = os::Linux::sendfile(_writer->get_fd(), segment_fd, &offset, st.st_size); if (ret == -1) { ::close(segment_fd); set_error("Failed to merge segmented heap file"); return; } } // As sendfile variant does not call the write method of the global writer, // bytes_written is also incorrect for this variant, we need to explicitly // accumulate bytes_written for the global writer in this case julong accum = _writer->bytes_written() + st.st_size; _writer->set_bytes_written(accum); ::close(segment_fd); } #else // Generic implementation using read+write void DumpMerger::merge_file(const char* path) { TraceTime timer("Merge segmented heap file", TRACETIME_LOG(Info, heapdump)); fileStream segment_fs(path, "rb"); if (!segment_fs.is_open()) { set_error("Can not open segmented heap file during merging"); return; } jlong total = 0; size_t cnt = 0; // Use _writer buffer for reading. while ((cnt = segment_fs.read(_writer->buffer(), 1, _writer->buffer_size())) != 0) { _writer->set_position(cnt); _writer->flush(); total += cnt; } if (segment_fs.fileSize() != total) { set_error("Merged heap dump is incomplete"); } } #endif void DumpMerger::do_merge() { TraceTime timer("Merge heap files complete", TRACETIME_LOG(Info, heapdump)); // Since contents in segmented heap file were already zipped, we don't need to zip // them again during merging. AbstractCompressor* saved_compressor = _writer->compressor(); _writer->set_compressor(nullptr); // Merge the content of the remaining files into base file. Regardless of whether // the merge process is successful or not, these segmented files will be deleted. for (int i = 0; i < _dump_seq; i++) { ResourceMark rm; const char* path = get_writer_path(_path, i); if (!_has_error) { merge_file(path); } // Delete selected segmented heap file nevertheless if (remove(path) != 0) { log_info(heapdump)("Removal of segment file (%d) failed (%d)", i, errno); } } // restore compressor for further use _writer->set_compressor(saved_compressor); merge_done(); } // The VM operation that performs the heap dump class VM_HeapDumper : public VM_GC_Operation, public WorkerTask, public UnmountedVThreadDumper { private: DumpWriter* _writer; JavaThread* _oome_thread; Method* _oome_constructor; bool _gc_before_heap_dump; GrowableArray* _klass_map; ThreadDumper** _thread_dumpers; // platform, carrier and mounted virtual threads int _thread_dumpers_count; volatile int _thread_serial_num; volatile int _frame_serial_num; volatile int _dump_seq; // parallel heap dump support uint _num_dumper_threads; DumperController* _dumper_controller; ParallelObjectIterator* _poi; // Dumper id of VMDumper thread. static const int VMDumperId = 0; // VM dumper dumps both heap and non-heap data, other dumpers dump heap-only data. static bool is_vm_dumper(int dumper_id) { return dumper_id == VMDumperId; } // the 1st dumper calling get_next_dumper_id becomes VM dumper int get_next_dumper_id() { return Atomic::fetch_then_add(&_dump_seq, 1); } DumpWriter* writer() const { return _writer; } bool skip_operation() const; // HPROF_GC_ROOT_THREAD_OBJ records for platform and mounted virtual threads void dump_threads(AbstractDumpWriter* writer); bool is_oom_thread(JavaThread* thread) const { return thread == _oome_thread && _oome_constructor != nullptr; } // HPROF_TRACE and HPROF_FRAME records for platform and mounted virtual threads void dump_stack_traces(AbstractDumpWriter* writer); public: VM_HeapDumper(DumpWriter* writer, bool gc_before_heap_dump, bool oome, uint num_dump_threads) : VM_GC_Operation(0 /* total collections, dummy, ignored */, GCCause::_heap_dump /* GC Cause */, 0 /* total full collections, dummy, ignored */, gc_before_heap_dump), WorkerTask("dump heap") { _writer = writer; _gc_before_heap_dump = gc_before_heap_dump; _klass_map = new (mtServiceability) GrowableArray(INITIAL_CLASS_COUNT, mtServiceability); _thread_dumpers = nullptr; _thread_dumpers_count = 0; _thread_serial_num = 1; _frame_serial_num = 1; _dump_seq = VMDumperId; _num_dumper_threads = num_dump_threads; _dumper_controller = nullptr; _poi = nullptr; if (oome) { assert(!Thread::current()->is_VM_thread(), "Dump from OutOfMemoryError cannot be called by the VMThread"); // get OutOfMemoryError zero-parameter constructor InstanceKlass* oome_ik = vmClasses::OutOfMemoryError_klass(); _oome_constructor = oome_ik->find_method(vmSymbols::object_initializer_name(), vmSymbols::void_method_signature()); // get thread throwing OOME when generating the heap dump at OOME _oome_thread = JavaThread::current(); } else { _oome_thread = nullptr; _oome_constructor = nullptr; } } ~VM_HeapDumper() { if (_thread_dumpers != nullptr) { for (int i = 0; i < _thread_dumpers_count; i++) { delete _thread_dumpers[i]; } FREE_C_HEAP_ARRAY(ThreadDumper*, _thread_dumpers); } if (_dumper_controller != nullptr) { delete _dumper_controller; _dumper_controller = nullptr; } delete _klass_map; } int dump_seq() { return _dump_seq; } bool is_parallel_dump() { return _num_dumper_threads > 1; } void prepare_parallel_dump(WorkerThreads* workers); VMOp_Type type() const { return VMOp_HeapDumper; } virtual bool doit_prologue(); void doit(); void work(uint worker_id); // UnmountedVThreadDumper implementation void dump_vthread(oop vt, AbstractDumpWriter* segment_writer); }; bool VM_HeapDumper::skip_operation() const { return false; } // fixes up the current dump record and writes HPROF_HEAP_DUMP_END record void DumperSupport::end_of_dump(AbstractDumpWriter* writer) { writer->finish_dump_segment(); writer->write_u1(HPROF_HEAP_DUMP_END); writer->write_u4(0); writer->write_u4(0); } // Write a HPROF_GC_ROOT_THREAD_OBJ record for platform/carrier and mounted virtual threads. // Then walk the stack so that locals and JNI locals are dumped. void VM_HeapDumper::dump_threads(AbstractDumpWriter* writer) { for (int i = 0; i < _thread_dumpers_count; i++) { _thread_dumpers[i]->dump_thread_obj(writer); _thread_dumpers[i]->dump_stack_refs(writer); } } bool VM_HeapDumper::doit_prologue() { if (_gc_before_heap_dump && (UseZGC || UseShenandoahGC)) { // ZGC and Shenandoah cannot perform a synchronous GC cycle from within the VM thread. // So collect_as_vm_thread() is a noop. To respect the _gc_before_heap_dump flag a // synchronous GC cycle is performed from the caller thread in the prologue. Universe::heap()->collect(GCCause::_heap_dump); } return VM_GC_Operation::doit_prologue(); } void VM_HeapDumper::prepare_parallel_dump(WorkerThreads* workers) { uint num_active_workers = workers != nullptr ? workers->active_workers() : 0; uint num_requested_dump_threads = _num_dumper_threads; // check if we can dump in parallel based on requested and active threads if (num_active_workers <= 1 || num_requested_dump_threads <= 1) { _num_dumper_threads = 1; } else { _num_dumper_threads = clamp(num_requested_dump_threads, 2U, num_active_workers); } _dumper_controller = new (std::nothrow) DumperController(_num_dumper_threads); bool can_parallel = _num_dumper_threads > 1; log_info(heapdump)("Requested dump threads %u, active dump threads %u, " "actual dump threads %u, parallelism %s", num_requested_dump_threads, num_active_workers, _num_dumper_threads, can_parallel ? "true" : "false"); } // The VM operation that dumps the heap. The dump consists of the following // records: // // HPROF_HEADER // [HPROF_UTF8]* // [HPROF_LOAD_CLASS]* // [[HPROF_FRAME]*|HPROF_TRACE]* // [HPROF_GC_CLASS_DUMP]* // [HPROF_HEAP_DUMP_SEGMENT]* // HPROF_HEAP_DUMP_END // // The HPROF_TRACE records represent the stack traces where the heap dump // is generated and a "dummy trace" record which does not include // any frames. The dummy trace record is used to be referenced as the // unknown object alloc site. // // Each HPROF_HEAP_DUMP_SEGMENT record has a length followed by sub-records. // To allow the heap dump be generated in a single pass we remember the position // of the dump length and fix it up after all sub-records have been written. // To generate the sub-records we iterate over the heap, writing // HPROF_GC_INSTANCE_DUMP, HPROF_GC_OBJ_ARRAY_DUMP, and HPROF_GC_PRIM_ARRAY_DUMP // records as we go. Once that is done we write records for some of the GC // roots. void VM_HeapDumper::doit() { CollectedHeap* ch = Universe::heap(); ch->ensure_parsability(false); // must happen, even if collection does // not happen (e.g. due to GCLocker) if (_gc_before_heap_dump) { if (GCLocker::is_active()) { warning("GC locker is held; pre-heapdump GC was skipped"); } else { ch->collect_as_vm_thread(GCCause::_heap_dump); } } WorkerThreads* workers = ch->safepoint_workers(); prepare_parallel_dump(workers); if (!is_parallel_dump()) { work(VMDumperId); } else { ParallelObjectIterator poi(_num_dumper_threads); _poi = &poi; workers->run_task(this, _num_dumper_threads); _poi = nullptr; } } void VM_HeapDumper::work(uint worker_id) { // VM Dumper works on all non-heap data dumping and part of heap iteration. int dumper_id = get_next_dumper_id(); if (is_vm_dumper(dumper_id)) { // lock global writer, it will be unlocked after VM Dumper finishes with non-heap data _dumper_controller->lock_global_writer(); _dumper_controller->signal_start(); } else { _dumper_controller->wait_for_start_signal(); } if (is_vm_dumper(dumper_id)) { TraceTime timer("Dump non-objects", TRACETIME_LOG(Info, heapdump)); // Write the file header - we always use 1.0.2 const char* header = "JAVA PROFILE 1.0.2"; // header is few bytes long - no chance to overflow int writer()->write_raw(header, strlen(header) + 1); // NUL terminated writer()->write_u4(oopSize); // timestamp is current time in ms writer()->write_u8(os::javaTimeMillis()); // HPROF_UTF8 records SymbolTableDumper sym_dumper(writer()); SymbolTable::symbols_do(&sym_dumper); // write HPROF_LOAD_CLASS records { LoadedClassDumper loaded_class_dumper(writer(), _klass_map); ClassLoaderDataGraph::classes_do(&loaded_class_dumper); } // write HPROF_FRAME and HPROF_TRACE records // this must be called after _klass_map is built when iterating the classes above. dump_stack_traces(writer()); // unlock global writer, so parallel dumpers can dump stack traces of unmounted virtual threads _dumper_controller->unlock_global_writer(); } // HPROF_HEAP_DUMP/HPROF_HEAP_DUMP_SEGMENT starts here ResourceMark rm; // share global compressor, local DumpWriter is not responsible for its life cycle DumpWriter segment_writer(DumpMerger::get_writer_path(writer()->get_file_path(), dumper_id), writer()->is_overwrite(), writer()->compressor()); if (!segment_writer.has_error()) { if (is_vm_dumper(dumper_id)) { // dump some non-heap subrecords to heap dump segment TraceTime timer("Dump non-objects (part 2)", TRACETIME_LOG(Info, heapdump)); // Writes HPROF_GC_CLASS_DUMP records ClassDumper class_dumper(&segment_writer); ClassLoaderDataGraph::classes_do(&class_dumper); // HPROF_GC_ROOT_THREAD_OBJ + frames + jni locals dump_threads(&segment_writer); // HPROF_GC_ROOT_JNI_GLOBAL JNIGlobalsDumper jni_dumper(&segment_writer); JNIHandles::oops_do(&jni_dumper); // technically not jni roots, but global roots // for things like preallocated throwable backtraces Universe::vm_global()->oops_do(&jni_dumper); // HPROF_GC_ROOT_STICKY_CLASS // These should be classes in the null class loader data, and not all classes // if !ClassUnloading StickyClassDumper stiky_class_dumper(&segment_writer); ClassLoaderData::the_null_class_loader_data()->classes_do(&stiky_class_dumper); } // Heap iteration. // writes HPROF_GC_INSTANCE_DUMP records. // After each sub-record is written check_segment_length will be invoked // to check if the current segment exceeds a threshold. If so, a new // segment is started. // The HPROF_GC_CLASS_DUMP and HPROF_GC_INSTANCE_DUMP are the vast bulk // of the heap dump. TraceTime timer(is_parallel_dump() ? "Dump heap objects in parallel" : "Dump heap objects", TRACETIME_LOG(Info, heapdump)); HeapObjectDumper obj_dumper(&segment_writer, this); if (!is_parallel_dump()) { Universe::heap()->object_iterate(&obj_dumper); } else { // == Parallel dump _poi->object_iterate(&obj_dumper, worker_id); } segment_writer.finish_dump_segment(); segment_writer.flush(); } _dumper_controller->dumper_complete(&segment_writer, writer()); if (is_vm_dumper(dumper_id)) { _dumper_controller->wait_all_dumpers_complete(); // flush global writer writer()->flush(); // At this point, all fragments of the heapdump have been written to separate files. // We need to merge them into a complete heapdump and write HPROF_HEAP_DUMP_END at that time. } } void VM_HeapDumper::dump_stack_traces(AbstractDumpWriter* writer) { // write a HPROF_TRACE record without any frames to be referenced as object alloc sites DumperSupport::write_header(writer, HPROF_TRACE, 3 * sizeof(u4)); writer->write_u4((u4)STACK_TRACE_ID); writer->write_u4(0); // thread number writer->write_u4(0); // frame count // max number if every platform thread is carrier with mounted virtual thread _thread_dumpers = NEW_C_HEAP_ARRAY(ThreadDumper*, Threads::number_of_threads() * 2, mtInternal); for (JavaThreadIteratorWithHandle jtiwh; JavaThread * thread = jtiwh.next(); ) { if (ThreadDumper::should_dump_pthread(thread)) { bool add_oom_frame = is_oom_thread(thread); oop mounted_vt = thread->is_vthread_mounted() ? thread->vthread() : nullptr; if (mounted_vt != nullptr && !ThreadDumper::should_dump_vthread(mounted_vt)) { mounted_vt = nullptr; } // mounted vthread (if any) if (mounted_vt != nullptr) { ThreadDumper* thread_dumper = new ThreadDumper(ThreadDumper::ThreadType::MountedVirtual, thread, mounted_vt); _thread_dumpers[_thread_dumpers_count++] = thread_dumper; if (add_oom_frame) { thread_dumper->add_oom_frame(_oome_constructor); // we add oom frame to the VT stack, don't add it to the carrier thread stack add_oom_frame = false; } thread_dumper->init_serial_nums(&_thread_serial_num, &_frame_serial_num); thread_dumper->dump_stack_traces(writer, _klass_map); } // platform or carrier thread ThreadDumper* thread_dumper = new ThreadDumper(ThreadDumper::ThreadType::Platform, thread, thread->threadObj()); _thread_dumpers[_thread_dumpers_count++] = thread_dumper; if (add_oom_frame) { thread_dumper->add_oom_frame(_oome_constructor); } thread_dumper->init_serial_nums(&_thread_serial_num, &_frame_serial_num); thread_dumper->dump_stack_traces(writer, _klass_map); } } } void VM_HeapDumper::dump_vthread(oop vt, AbstractDumpWriter* segment_writer) { // unmounted vthread has no JavaThread ThreadDumper thread_dumper(ThreadDumper::ThreadType::UnmountedVirtual, nullptr, vt); thread_dumper.init_serial_nums(&_thread_serial_num, &_frame_serial_num); // write HPROF_TRACE/HPROF_FRAME records to global writer _dumper_controller->lock_global_writer(); thread_dumper.dump_stack_traces(writer(), _klass_map); _dumper_controller->unlock_global_writer(); // write HPROF_GC_ROOT_THREAD_OBJ/HPROF_GC_ROOT_JAVA_FRAME/HPROF_GC_ROOT_JNI_LOCAL subrecord // to segment writer thread_dumper.dump_thread_obj(segment_writer); thread_dumper.dump_stack_refs(segment_writer); } // dump the heap to given path. int HeapDumper::dump(const char* path, outputStream* out, int compression, bool overwrite, uint num_dump_threads) { assert(path != nullptr && strlen(path) > 0, "path missing"); // print message in interactive case if (out != nullptr) { out->print_cr("Dumping heap to %s ...", path); timer()->start(); } if (_oome && num_dump_threads > 1) { // Each additional parallel writer requires several MB of internal memory // (DumpWriter buffer, DumperClassCacheTable, GZipCompressor buffers). // For the OOM handling we may already be limited in memory. // Lets ensure we have at least 20MB per thread. julong max_threads = os::free_memory() / (20 * M); if (num_dump_threads > max_threads) { num_dump_threads = MAX2(1, (uint)max_threads); } } // create JFR event EventHeapDump event; AbstractCompressor* compressor = nullptr; if (compression > 0) { compressor = new (std::nothrow) GZipCompressor(compression); if (compressor == nullptr) { set_error("Could not allocate gzip compressor"); return -1; } } DumpWriter writer(path, overwrite, compressor); if (writer.error() != nullptr) { set_error(writer.error()); if (out != nullptr) { out->print_cr("Unable to create %s: %s", path, (error() != nullptr) ? error() : "reason unknown"); } return -1; } // generate the segmented heap dump into separate files VM_HeapDumper dumper(&writer, _gc_before_heap_dump, _oome, num_dump_threads); VMThread::execute(&dumper); // record any error that the writer may have encountered set_error(writer.error()); // Heap dump process is done in two phases // // Phase 1: Concurrent threads directly write heap data to multiple heap files. // This is done by VM_HeapDumper, which is performed within safepoint. // // Phase 2: Merge multiple heap files into one complete heap dump file. // This is done by DumpMerger, which is performed outside safepoint DumpMerger merger(path, &writer, dumper.dump_seq()); // Perform heapdump file merge operation in the current thread prevents us // from occupying the VM Thread, which in turn affects the occurrence of // GC and other VM operations. merger.do_merge(); if (writer.error() != nullptr) { set_error(writer.error()); } // emit JFR event if (error() == nullptr) { event.set_destination(path); event.set_gcBeforeDump(_gc_before_heap_dump); event.set_size(writer.bytes_written()); event.set_onOutOfMemoryError(_oome); event.set_overwrite(overwrite); event.set_compression(compression); event.commit(); } else { log_debug(aot, heap)("Error %s while dumping heap", error()); } // print message in interactive case if (out != nullptr) { timer()->stop(); if (error() == nullptr) { out->print_cr("Heap dump file created [" JULONG_FORMAT " bytes in %3.3f secs]", writer.bytes_written(), timer()->seconds()); } else { out->print_cr("Dump file is incomplete: %s", writer.error()); } } if (compressor != nullptr) { delete compressor; } return (writer.error() == nullptr) ? 0 : -1; } // stop timer (if still active), and free any error string we might be holding HeapDumper::~HeapDumper() { if (timer()->is_active()) { timer()->stop(); } set_error(nullptr); } // returns the error string (resource allocated), or null char* HeapDumper::error_as_C_string() const { if (error() != nullptr) { char* str = ResourceArea::strdup(error()); return str; } else { return nullptr; } } // set the error string void HeapDumper::set_error(char const* error) { if (_error != nullptr) { os::free(_error); } if (error == nullptr) { _error = nullptr; } else { _error = os::strdup(error); assert(_error != nullptr, "allocation failure"); } } // Called by out-of-memory error reporting by a single Java thread // outside of a JVM safepoint void HeapDumper::dump_heap_from_oome() { HeapDumper::dump_heap(true); } // Called by error reporting by a single Java thread outside of a JVM safepoint, // or by heap dumping by the VM thread during a (GC) safepoint. Thus, these various // callers are strictly serialized and guaranteed not to interfere below. For more // general use, however, this method will need modification to prevent // inteference when updating the static variables base_path and dump_file_seq below. void HeapDumper::dump_heap() { HeapDumper::dump_heap(false); } void HeapDumper::dump_heap(bool oome) { static char base_path[JVM_MAXPATHLEN] = {'\0'}; static uint dump_file_seq = 0; char my_path[JVM_MAXPATHLEN]; const int max_digit_chars = 20; const char* dump_file_name = HeapDumpGzipLevel > 0 ? "java_pid%p.hprof.gz" : "java_pid%p.hprof"; // The dump file defaults to java_pid.hprof in the current working // directory. HeapDumpPath= can be used to specify an alternative // dump file name or a directory where dump file is created. if (dump_file_seq == 0) { // first time in, we initialize base_path // Set base path (name or directory, default or custom, without seq no), doing %p substitution. const char *path_src = (HeapDumpPath != nullptr && HeapDumpPath[0] != '\0') ? HeapDumpPath : dump_file_name; if (!Arguments::copy_expand_pid(path_src, strlen(path_src), base_path, JVM_MAXPATHLEN - max_digit_chars)) { warning("Cannot create heap dump file. HeapDumpPath is too long."); return; } // Check if the path is an existing directory DIR* dir = os::opendir(base_path); if (dir != nullptr) { os::closedir(dir); // Path is a directory. Append a file separator (if needed). size_t fs_len = strlen(os::file_separator()); if (strlen(base_path) >= fs_len) { char* end = base_path; end += (strlen(base_path) - fs_len); if (strcmp(end, os::file_separator()) != 0) { strcat(base_path, os::file_separator()); } } // Then add the default name, with %p substitution. Use my_path temporarily. if (!Arguments::copy_expand_pid(dump_file_name, strlen(dump_file_name), my_path, JVM_MAXPATHLEN - max_digit_chars)) { warning("Cannot create heap dump file. HeapDumpPath is too long."); return; } const size_t dlen = strlen(base_path); jio_snprintf(&base_path[dlen], sizeof(base_path) - dlen, "%s", my_path); } strncpy(my_path, base_path, JVM_MAXPATHLEN); } else { // Append a sequence number id for dumps following the first const size_t len = strlen(base_path) + max_digit_chars + 2; // for '.' and \0 jio_snprintf(my_path, len, "%s.%d", base_path, dump_file_seq); } dump_file_seq++; // increment seq number for next time we dump HeapDumper dumper(false /* no GC before heap dump */, oome /* pass along out-of-memory-error flag */); dumper.dump(my_path, tty, HeapDumpGzipLevel); }