/* * Copyright (c) 2003, 2025, Oracle and/or its affiliates. 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/javaClasses.inline.hpp" #include "classfile/systemDictionary.hpp" #include "classfile/vmClasses.hpp" #include "classfile/vmSymbols.hpp" #include "gc/shared/oopStorageSet.hpp" #include "memory/heapInspection.hpp" #include "memory/oopFactory.hpp" #include "memory/resourceArea.hpp" #include "memory/universe.hpp" #include "nmt/memTag.hpp" #include "oops/instanceKlass.hpp" #include "oops/klass.inline.hpp" #include "oops/method.inline.hpp" #include "oops/objArrayKlass.hpp" #include "oops/objArrayOop.inline.hpp" #include "oops/oop.inline.hpp" #include "oops/oopHandle.inline.hpp" #include "prims/jvmtiRawMonitor.hpp" #include "prims/jvmtiThreadState.hpp" #include "runtime/atomic.hpp" #include "runtime/handles.inline.hpp" #include "runtime/init.hpp" #include "runtime/javaCalls.hpp" #include "runtime/javaThread.inline.hpp" #include "runtime/jniHandles.inline.hpp" #include "runtime/objectMonitor.inline.hpp" #include "runtime/synchronizer.inline.hpp" #include "runtime/thread.inline.hpp" #include "runtime/threads.hpp" #include "runtime/threadSMR.inline.hpp" #include "runtime/vframe.inline.hpp" #include "runtime/vmThread.hpp" #include "runtime/vmOperations.hpp" #include "services/threadService.hpp" // TODO: we need to define a naming convention for perf counters // to distinguish counters for: // - standard JSR174 use // - Hotspot extension (public and committed) // - Hotspot extension (private/internal and uncommitted) // Default is disabled. bool ThreadService::_thread_monitoring_contention_enabled = false; bool ThreadService::_thread_cpu_time_enabled = false; bool ThreadService::_thread_allocated_memory_enabled = false; PerfCounter* ThreadService::_total_threads_count = nullptr; PerfVariable* ThreadService::_live_threads_count = nullptr; PerfVariable* ThreadService::_peak_threads_count = nullptr; PerfVariable* ThreadService::_daemon_threads_count = nullptr; volatile int ThreadService::_atomic_threads_count = 0; volatile int ThreadService::_atomic_daemon_threads_count = 0; volatile jlong ThreadService::_exited_allocated_bytes = 0; ThreadDumpResult* ThreadService::_threaddump_list = nullptr; static const int INITIAL_ARRAY_SIZE = 10; // OopStorage for thread stack sampling static OopStorage* _thread_service_storage = nullptr; void ThreadService::init() { EXCEPTION_MARK; // These counters are for java.lang.management API support. // They are created even if -XX:-UsePerfData is set and in // that case, they will be allocated on C heap. _total_threads_count = PerfDataManager::create_counter(JAVA_THREADS, "started", PerfData::U_Events, CHECK); _live_threads_count = PerfDataManager::create_variable(JAVA_THREADS, "live", PerfData::U_None, CHECK); _peak_threads_count = PerfDataManager::create_variable(JAVA_THREADS, "livePeak", PerfData::U_None, CHECK); _daemon_threads_count = PerfDataManager::create_variable(JAVA_THREADS, "daemon", PerfData::U_None, CHECK); if (os::is_thread_cpu_time_supported()) { _thread_cpu_time_enabled = true; } _thread_allocated_memory_enabled = true; // Always on, so enable it // Initialize OopStorage for thread stack sampling walking _thread_service_storage = OopStorageSet::create_strong("ThreadService OopStorage", mtServiceability); } void ThreadService::reset_peak_thread_count() { // Acquire the lock to update the peak thread count // to synchronize with thread addition and removal. MutexLocker mu(Threads_lock); _peak_threads_count->set_value(get_live_thread_count()); } static bool is_hidden_thread(JavaThread *thread) { // hide VM internal or JVMTI agent threads return thread->is_hidden_from_external_view() || thread->is_jvmti_agent_thread(); } void ThreadService::add_thread(JavaThread* thread, bool daemon) { assert(Threads_lock->owned_by_self(), "must have threads lock"); // Do not count hidden threads if (is_hidden_thread(thread)) { return; } _total_threads_count->inc(); _live_threads_count->inc(); Atomic::inc(&_atomic_threads_count); int count = _atomic_threads_count; if (count > _peak_threads_count->get_value()) { _peak_threads_count->set_value(count); } if (daemon) { _daemon_threads_count->inc(); Atomic::inc(&_atomic_daemon_threads_count); } } void ThreadService::decrement_thread_counts(JavaThread* jt, bool daemon) { Atomic::dec(&_atomic_threads_count); if (daemon) { Atomic::dec(&_atomic_daemon_threads_count); } } void ThreadService::remove_thread(JavaThread* thread, bool daemon) { assert(Threads_lock->owned_by_self(), "must have threads lock"); // Include hidden thread allcations in exited_allocated_bytes ThreadService::incr_exited_allocated_bytes(thread->cooked_allocated_bytes()); // Do not count hidden threads if (is_hidden_thread(thread)) { return; } assert(!thread->is_terminated(), "must not be terminated"); if (!thread->is_exiting()) { // We did not get here via JavaThread::exit() so current_thread_exiting() // was not called, e.g., JavaThread::cleanup_failed_attach_current_thread(). decrement_thread_counts(thread, daemon); } int daemon_count = _atomic_daemon_threads_count; int count = _atomic_threads_count; // Counts are incremented at the same time, but atomic counts are // decremented earlier than perf counts. assert(_live_threads_count->get_value() > count, "thread count mismatch %d : %d", (int)_live_threads_count->get_value(), count); _live_threads_count->dec(1); if (daemon) { assert(_daemon_threads_count->get_value() > daemon_count, "thread count mismatch %d : %d", (int)_daemon_threads_count->get_value(), daemon_count); _daemon_threads_count->dec(1); } // Counts are incremented at the same time, but atomic counts are // decremented earlier than perf counts. assert(_daemon_threads_count->get_value() >= daemon_count, "thread count mismatch %d : %d", (int)_daemon_threads_count->get_value(), daemon_count); assert(_live_threads_count->get_value() >= count, "thread count mismatch %d : %d", (int)_live_threads_count->get_value(), count); assert(_live_threads_count->get_value() > 0 || (_live_threads_count->get_value() == 0 && count == 0 && _daemon_threads_count->get_value() == 0 && daemon_count == 0), "thread counts should reach 0 at the same time, live %d,%d daemon %d,%d", (int)_live_threads_count->get_value(), count, (int)_daemon_threads_count->get_value(), daemon_count); assert(_daemon_threads_count->get_value() > 0 || (_daemon_threads_count->get_value() == 0 && daemon_count == 0), "thread counts should reach 0 at the same time, daemon %d,%d", (int)_daemon_threads_count->get_value(), daemon_count); } void ThreadService::current_thread_exiting(JavaThread* jt, bool daemon) { // Do not count hidden threads if (is_hidden_thread(jt)) { return; } assert(jt == JavaThread::current(), "Called by current thread"); assert(!jt->is_terminated() && jt->is_exiting(), "must be exiting"); decrement_thread_counts(jt, daemon); } // FIXME: JVMTI should call this function Handle ThreadService::get_current_contended_monitor(JavaThread* thread) { assert(thread != nullptr, "should be non-null"); DEBUG_ONLY(Thread::check_for_dangling_thread_pointer(thread);) // This function can be called on a target JavaThread that is not // the caller and we are not at a safepoint. So it is possible for // the waiting or pending condition to be over/stale and for the // first stage of async deflation to clear the object field in // the ObjectMonitor. It is also possible for the object to be // inflated again and to be associated with a completely different // ObjectMonitor by the time this object reference is processed // by the caller. ObjectMonitor *wait_obj = thread->current_waiting_monitor(); oop obj = nullptr; if (wait_obj != nullptr) { // thread is doing an Object.wait() call obj = wait_obj->object(); } else { ObjectMonitor *enter_obj = thread->current_pending_monitor(); if (enter_obj != nullptr) { // thread is trying to enter() an ObjectMonitor. obj = enter_obj->object(); } } Handle h(Thread::current(), obj); return h; } bool ThreadService::set_thread_monitoring_contention(bool flag) { MutexLocker m(Management_lock); bool prev = _thread_monitoring_contention_enabled; _thread_monitoring_contention_enabled = flag; return prev; } bool ThreadService::set_thread_cpu_time_enabled(bool flag) { MutexLocker m(Management_lock); bool prev = _thread_cpu_time_enabled; _thread_cpu_time_enabled = flag; return prev; } bool ThreadService::set_thread_allocated_memory_enabled(bool flag) { MutexLocker m(Management_lock); bool prev = _thread_allocated_memory_enabled; _thread_allocated_memory_enabled = flag; return prev; } void ThreadService::metadata_do(void f(Metadata*)) { for (ThreadDumpResult* dump = _threaddump_list; dump != nullptr; dump = dump->next()) { dump->metadata_do(f); } } void ThreadService::add_thread_dump(ThreadDumpResult* dump) { MutexLocker ml(Management_lock); if (_threaddump_list == nullptr) { _threaddump_list = dump; } else { dump->set_next(_threaddump_list); _threaddump_list = dump; } } void ThreadService::remove_thread_dump(ThreadDumpResult* dump) { MutexLocker ml(Management_lock); ThreadDumpResult* prev = nullptr; bool found = false; for (ThreadDumpResult* d = _threaddump_list; d != nullptr; prev = d, d = d->next()) { if (d == dump) { if (prev == nullptr) { _threaddump_list = dump->next(); } else { prev->set_next(dump->next()); } found = true; break; } } assert(found, "The threaddump result to be removed must exist."); } // Dump stack trace of threads specified in the given threads array. // Returns StackTraceElement[][] each element is the stack trace of a thread in // the corresponding entry in the given threads array Handle ThreadService::dump_stack_traces(GrowableArray* threads, int num_threads, TRAPS) { assert(num_threads > 0, "just checking"); ThreadDumpResult dump_result; VM_ThreadDump op(&dump_result, threads, num_threads, -1, /* entire stack */ false, /* with locked monitors */ false /* with locked synchronizers */); VMThread::execute(&op); // Allocate the resulting StackTraceElement[][] object ResourceMark rm(THREAD); Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_StackTraceElement_array(), true, CHECK_NH); ObjArrayKlass* ik = ObjArrayKlass::cast(k); objArrayOop r = oopFactory::new_objArray(ik, num_threads, CHECK_NH); objArrayHandle result_obj(THREAD, r); int num_snapshots = dump_result.num_snapshots(); assert(num_snapshots == num_threads, "Must have num_threads thread snapshots"); assert(num_snapshots == 0 || dump_result.t_list_has_been_set(), "ThreadsList must have been set if we have a snapshot"); int i = 0; for (ThreadSnapshot* ts = dump_result.snapshots(); ts != nullptr; i++, ts = ts->next()) { ThreadStackTrace* stacktrace = ts->get_stack_trace(); if (stacktrace == nullptr) { // No stack trace result_obj->obj_at_put(i, nullptr); } else { // Construct an array of java/lang/StackTraceElement object Handle backtrace_h = stacktrace->allocate_fill_stack_trace_element_array(CHECK_NH); result_obj->obj_at_put(i, backtrace_h()); } } return result_obj; } void ThreadService::reset_contention_count_stat(JavaThread* thread) { ThreadStatistics* stat = thread->get_thread_stat(); if (stat != nullptr) { stat->reset_count_stat(); } } void ThreadService::reset_contention_time_stat(JavaThread* thread) { ThreadStatistics* stat = thread->get_thread_stat(); if (stat != nullptr) { stat->reset_time_stat(); } } bool ThreadService::is_virtual_or_carrier_thread(JavaThread* jt) { oop threadObj = jt->threadObj(); if (threadObj != nullptr && threadObj->is_a(vmClasses::BaseVirtualThread_klass())) { // a virtual thread backed by JavaThread return true; } if (jt->is_vthread_mounted()) { // carrier thread return true; } return false; } // Find deadlocks involving raw monitors, object monitors and concurrent locks // if concurrent_locks is true. // We skip virtual thread carriers under the assumption that the current scheduler, ForkJoinPool, // doesn't hold any locks while mounting a virtual thread, so any owned monitor (or j.u.c., lock for that matter) // on that JavaThread must be owned by the virtual thread, and we don't support deadlock detection for virtual threads. DeadlockCycle* ThreadService::find_deadlocks_at_safepoint(ThreadsList * t_list, bool concurrent_locks) { assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint"); // This code was modified from the original Threads::find_deadlocks code. int globalDfn = 0, thisDfn; ObjectMonitor* waitingToLockMonitor = nullptr; JvmtiRawMonitor* waitingToLockRawMonitor = nullptr; oop waitingToLockBlocker = nullptr; bool blocked_on_monitor = false; JavaThread *currentThread, *previousThread; int num_deadlocks = 0; // Initialize the depth-first-number for each JavaThread. JavaThreadIterator jti(t_list); for (JavaThread* jt = jti.first(); jt != nullptr; jt = jti.next()) { if (!is_virtual_or_carrier_thread(jt)) { jt->set_depth_first_number(-1); } } DeadlockCycle* deadlocks = nullptr; DeadlockCycle* last = nullptr; DeadlockCycle* cycle = new DeadlockCycle(); for (JavaThread* jt = jti.first(); jt != nullptr; jt = jti.next()) { if (is_virtual_or_carrier_thread(jt)) { // skip virtual and carrier threads continue; } if (jt->depth_first_number() >= 0) { // this thread was already visited continue; } thisDfn = globalDfn; jt->set_depth_first_number(globalDfn++); previousThread = jt; currentThread = jt; cycle->reset(); // The ObjectMonitor* can't be async deflated since we are at a safepoint. // When there is a deadlock, all the monitors involved in the dependency // cycle must be contended and heavyweight. So we only care about the // heavyweight monitor a thread is waiting to lock. waitingToLockMonitor = jt->current_pending_monitor(); // JVM TI raw monitors can also be involved in deadlocks, and we can be // waiting to lock both a raw monitor and ObjectMonitor at the same time. // It isn't clear how to make deadlock detection work correctly if that // happens. waitingToLockRawMonitor = jt->current_pending_raw_monitor(); if (concurrent_locks) { waitingToLockBlocker = jt->current_park_blocker(); } while (waitingToLockMonitor != nullptr || waitingToLockRawMonitor != nullptr || waitingToLockBlocker != nullptr) { cycle->add_thread(currentThread); // Give preference to the raw monitor if (waitingToLockRawMonitor != nullptr) { Thread* owner = waitingToLockRawMonitor->owner(); if (owner != nullptr && // the raw monitor could be released at any time owner->is_Java_thread()) { currentThread = JavaThread::cast(owner); } } else if (waitingToLockMonitor != nullptr) { if (waitingToLockMonitor->has_owner()) { currentThread = Threads::owning_thread_from_monitor(t_list, waitingToLockMonitor); // If currentThread is null we would like to know if the owner // is an unmounted vthread (no JavaThread*), because if it's not, // it would mean the previous currentThread is blocked permanently // and we should record this as a deadlock. Since there is currently // no fast way to determine if the owner is indeed an unmounted // vthread we never record this as a deadlock. Note: unless there // is a bug in the VM, or a thread exits without releasing monitors // acquired through JNI, null should imply an unmounted vthread owner. } } else { if (concurrent_locks) { if (waitingToLockBlocker->is_a(vmClasses::java_util_concurrent_locks_AbstractOwnableSynchronizer_klass())) { oop threadObj = java_util_concurrent_locks_AbstractOwnableSynchronizer::get_owner_threadObj(waitingToLockBlocker); // This JavaThread (if there is one) is protected by the // ThreadsListSetter in VM_FindDeadlocks::doit(). currentThread = threadObj != nullptr ? java_lang_Thread::thread(threadObj) : nullptr; } else { currentThread = nullptr; } } } if (currentThread == nullptr || is_virtual_or_carrier_thread(currentThread)) { // No dependency on another thread break; } if (currentThread->depth_first_number() < 0) { // First visit to this thread currentThread->set_depth_first_number(globalDfn++); } else if (currentThread->depth_first_number() < thisDfn) { // Thread already visited, and not on a (new) cycle break; } else if (currentThread == previousThread) { // Self-loop, ignore break; } else { // We have a (new) cycle num_deadlocks++; // add this cycle to the deadlocks list if (deadlocks == nullptr) { deadlocks = cycle; } else { last->set_next(cycle); } last = cycle; cycle = new DeadlockCycle(); break; } previousThread = currentThread; waitingToLockMonitor = (ObjectMonitor*)currentThread->current_pending_monitor(); if (concurrent_locks) { waitingToLockBlocker = currentThread->current_park_blocker(); } } } delete cycle; return deadlocks; } ThreadDumpResult::ThreadDumpResult() : _num_threads(0), _num_snapshots(0), _snapshots(nullptr), _last(nullptr), _next(nullptr), _setter() { // Create a new ThreadDumpResult object and append to the list. // If GC happens before this function returns, Method* // in the stack trace will be visited. ThreadService::add_thread_dump(this); } ThreadDumpResult::ThreadDumpResult(int num_threads) : _num_threads(num_threads), _num_snapshots(0), _snapshots(nullptr), _last(nullptr), _next(nullptr), _setter() { // Create a new ThreadDumpResult object and append to the list. // If GC happens before this function returns, oops // will be visited. ThreadService::add_thread_dump(this); } ThreadDumpResult::~ThreadDumpResult() { ThreadService::remove_thread_dump(this); // free all the ThreadSnapshot objects created during // the VM_ThreadDump operation ThreadSnapshot* ts = _snapshots; while (ts != nullptr) { ThreadSnapshot* p = ts; ts = ts->next(); delete p; } } ThreadSnapshot* ThreadDumpResult::add_thread_snapshot() { ThreadSnapshot* ts = new ThreadSnapshot(); link_thread_snapshot(ts); return ts; } ThreadSnapshot* ThreadDumpResult::add_thread_snapshot(JavaThread* thread) { ThreadSnapshot* ts = new ThreadSnapshot(); link_thread_snapshot(ts); ts->initialize(t_list(), thread); return ts; } void ThreadDumpResult::link_thread_snapshot(ThreadSnapshot* ts) { assert(_num_threads == 0 || _num_snapshots < _num_threads, "_num_snapshots must be less than _num_threads"); _num_snapshots++; if (_snapshots == nullptr) { _snapshots = ts; } else { _last->set_next(ts); } _last = ts; } void ThreadDumpResult::metadata_do(void f(Metadata*)) { for (ThreadSnapshot* ts = _snapshots; ts != nullptr; ts = ts->next()) { ts->metadata_do(f); } } ThreadsList* ThreadDumpResult::t_list() { return _setter.list(); } StackFrameInfo::StackFrameInfo(javaVFrame* jvf, bool with_lock_info) { _method = jvf->method(); _bci = jvf->bci(); _class_holder = OopHandle(_thread_service_storage, _method->method_holder()->klass_holder()); _locked_monitors = nullptr; if (with_lock_info) { Thread* current_thread = Thread::current(); ResourceMark rm(current_thread); HandleMark hm(current_thread); GrowableArray* list = jvf->locked_monitors(); int length = list->length(); if (length > 0) { _locked_monitors = new (mtServiceability) GrowableArray(length, mtServiceability); for (int i = 0; i < length; i++) { MonitorInfo* monitor = list->at(i); assert(monitor->owner() != nullptr, "This monitor must have an owning object"); _locked_monitors->append(OopHandle(_thread_service_storage, monitor->owner())); } } } } StackFrameInfo::~StackFrameInfo() { if (_locked_monitors != nullptr) { for (int i = 0; i < _locked_monitors->length(); i++) { _locked_monitors->at(i).release(_thread_service_storage); } delete _locked_monitors; } _class_holder.release(_thread_service_storage); } void StackFrameInfo::metadata_do(void f(Metadata*)) { f(_method); } void StackFrameInfo::print_on(outputStream* st) const { ResourceMark rm; java_lang_Throwable::print_stack_element(st, method(), bci()); int len = (_locked_monitors != nullptr ? _locked_monitors->length() : 0); for (int i = 0; i < len; i++) { oop o = _locked_monitors->at(i).resolve(); st->print_cr("\t- locked <" INTPTR_FORMAT "> (a %s)", p2i(o), o->klass()->external_name()); } } // Iterate through monitor cache to find JNI locked monitors class InflatedMonitorsClosure: public MonitorClosure { private: ThreadStackTrace* _stack_trace; public: InflatedMonitorsClosure(ThreadStackTrace* st) { _stack_trace = st; } void do_monitor(ObjectMonitor* mid) { oop object = mid->object(); if (!_stack_trace->is_owned_monitor_on_stack(object)) { _stack_trace->add_jni_locked_monitor(object); } } }; ThreadStackTrace::ThreadStackTrace(JavaThread* t, bool with_locked_monitors) { _thread = t; _frames = new (mtServiceability) GrowableArray(INITIAL_ARRAY_SIZE, mtServiceability); _depth = 0; _with_locked_monitors = with_locked_monitors; if (_with_locked_monitors) { _jni_locked_monitors = new (mtServiceability) GrowableArray(INITIAL_ARRAY_SIZE, mtServiceability); } else { _jni_locked_monitors = nullptr; } } void ThreadStackTrace::add_jni_locked_monitor(oop object) { _jni_locked_monitors->append(OopHandle(_thread_service_storage, object)); } ThreadStackTrace::~ThreadStackTrace() { for (int i = 0; i < _frames->length(); i++) { delete _frames->at(i); } delete _frames; if (_jni_locked_monitors != nullptr) { for (int i = 0; i < _jni_locked_monitors->length(); i++) { _jni_locked_monitors->at(i).release(_thread_service_storage); } delete _jni_locked_monitors; } } void ThreadStackTrace::dump_stack_at_safepoint(int maxDepth, ObjectMonitorsView* monitors, bool full) { assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped"); if (_thread->has_last_Java_frame()) { RegisterMap reg_map(_thread, RegisterMap::UpdateMap::include, RegisterMap::ProcessFrames::include, RegisterMap::WalkContinuation::skip); ResourceMark rm(VMThread::vm_thread()); // If full, we want to print both vthread and carrier frames vframe* start_vf = !full && _thread->is_vthread_mounted() ? _thread->carrier_last_java_vframe(®_map) : _thread->last_java_vframe(®_map); int count = 0; for (vframe* f = start_vf; f; f = f->sender() ) { if (maxDepth >= 0 && count == maxDepth) { // Skip frames if more than maxDepth break; } if (!full && f->is_vthread_entry()) { break; } if (f->is_java_frame()) { javaVFrame* jvf = javaVFrame::cast(f); add_stack_frame(jvf); count++; } else { // Ignore non-Java frames } } } if (_with_locked_monitors) { // Iterate inflated monitors and find monitors locked by this thread // that are not found in the stack, e.g. JNI locked monitors: InflatedMonitorsClosure imc(this); monitors->visit(&imc, _thread); } } bool ThreadStackTrace::is_owned_monitor_on_stack(oop object) { assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped"); bool found = false; int num_frames = get_stack_depth(); for (int depth = 0; depth < num_frames; depth++) { StackFrameInfo* frame = stack_frame_at(depth); int len = frame->num_locked_monitors(); GrowableArray* locked_monitors = frame->locked_monitors(); for (int j = 0; j < len; j++) { oop monitor = locked_monitors->at(j).resolve(); assert(monitor != nullptr, "must be a Java object"); if (monitor == object) { found = true; break; } } } return found; } Handle ThreadStackTrace::allocate_fill_stack_trace_element_array(TRAPS) { InstanceKlass* ik = vmClasses::StackTraceElement_klass(); assert(ik != nullptr, "must be loaded in 1.4+"); // Allocate an array of java/lang/StackTraceElement object objArrayOop ste = oopFactory::new_objArray(ik, _depth, CHECK_NH); objArrayHandle backtrace(THREAD, ste); for (int j = 0; j < _depth; j++) { StackFrameInfo* frame = _frames->at(j); methodHandle mh(THREAD, frame->method()); oop element = java_lang_StackTraceElement::create(mh, frame->bci(), CHECK_NH); backtrace->obj_at_put(j, element); } return backtrace; } void ThreadStackTrace::add_stack_frame(javaVFrame* jvf) { StackFrameInfo* frame = new StackFrameInfo(jvf, _with_locked_monitors); _frames->append(frame); _depth++; } void ThreadStackTrace::metadata_do(void f(Metadata*)) { int length = _frames->length(); for (int i = 0; i < length; i++) { _frames->at(i)->metadata_do(f); } } ConcurrentLocksDump::~ConcurrentLocksDump() { if (_retain_map_on_free) { return; } for (ThreadConcurrentLocks* t = _map; t != nullptr;) { ThreadConcurrentLocks* tcl = t; t = t->next(); delete tcl; } } void ConcurrentLocksDump::dump_at_safepoint() { // dump all locked concurrent locks assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped"); GrowableArray* aos_objects = new (mtServiceability) GrowableArray(INITIAL_ARRAY_SIZE, mtServiceability); // Find all instances of AbstractOwnableSynchronizer HeapInspection::find_instances_at_safepoint(vmClasses::java_util_concurrent_locks_AbstractOwnableSynchronizer_klass(), aos_objects); // Build a map of thread to its owned AQS locks build_map(aos_objects); delete aos_objects; } // build a map of JavaThread to all its owned AbstractOwnableSynchronizer void ConcurrentLocksDump::build_map(GrowableArray* aos_objects) { int length = aos_objects->length(); for (int i = 0; i < length; i++) { oop o = aos_objects->at(i); oop owner_thread_obj = java_util_concurrent_locks_AbstractOwnableSynchronizer::get_owner_threadObj(o); if (owner_thread_obj != nullptr) { // See comments in ThreadConcurrentLocks to see how this // JavaThread* is protected. JavaThread* thread = java_lang_Thread::thread(owner_thread_obj); assert(o->is_instance(), "Must be an instanceOop"); add_lock(thread, (instanceOop) o); } } } void ConcurrentLocksDump::add_lock(JavaThread* thread, instanceOop o) { ThreadConcurrentLocks* tcl = thread_concurrent_locks(thread); if (tcl != nullptr) { tcl->add_lock(o); return; } // First owned lock found for this thread tcl = new ThreadConcurrentLocks(thread); tcl->add_lock(o); if (_map == nullptr) { _map = tcl; } else { _last->set_next(tcl); } _last = tcl; } ThreadConcurrentLocks* ConcurrentLocksDump::thread_concurrent_locks(JavaThread* thread) { for (ThreadConcurrentLocks* tcl = _map; tcl != nullptr; tcl = tcl->next()) { if (tcl->java_thread() == thread) { return tcl; } } return nullptr; } void ConcurrentLocksDump::print_locks_on(JavaThread* t, outputStream* st) { st->print_cr(" Locked ownable synchronizers:"); ThreadConcurrentLocks* tcl = thread_concurrent_locks(t); GrowableArray* locks = (tcl != nullptr ? tcl->owned_locks() : nullptr); if (locks == nullptr || locks->is_empty()) { st->print_cr("\t- None"); st->cr(); return; } for (int i = 0; i < locks->length(); i++) { oop obj = locks->at(i).resolve(); st->print_cr("\t- <" INTPTR_FORMAT "> (a %s)", p2i(obj), obj->klass()->external_name()); } st->cr(); } ThreadConcurrentLocks::ThreadConcurrentLocks(JavaThread* thread) { _thread = thread; _owned_locks = new (mtServiceability) GrowableArray(INITIAL_ARRAY_SIZE, mtServiceability); _next = nullptr; } ThreadConcurrentLocks::~ThreadConcurrentLocks() { for (int i = 0; i < _owned_locks->length(); i++) { _owned_locks->at(i).release(_thread_service_storage); } delete _owned_locks; } void ThreadConcurrentLocks::add_lock(instanceOop o) { _owned_locks->append(OopHandle(_thread_service_storage, o)); } ThreadStatistics::ThreadStatistics() { _contended_enter_count = 0; _monitor_wait_count = 0; _sleep_count = 0; _count_pending_reset = false; _timer_pending_reset = false; memset((void*) _perf_recursion_counts, 0, sizeof(_perf_recursion_counts)); } oop ThreadSnapshot::threadObj() const { return _threadObj.resolve(); } void ThreadSnapshot::initialize(ThreadsList * t_list, JavaThread* thread) { _thread = thread; oop threadObj = thread->threadObj(); _threadObj = OopHandle(_thread_service_storage, threadObj); ThreadStatistics* stat = thread->get_thread_stat(); _contended_enter_ticks = stat->contended_enter_ticks(); _contended_enter_count = stat->contended_enter_count(); _monitor_wait_ticks = stat->monitor_wait_ticks(); _monitor_wait_count = stat->monitor_wait_count(); _sleep_ticks = stat->sleep_ticks(); _sleep_count = stat->sleep_count(); // If thread is still attaching then threadObj will be null. _thread_status = threadObj == nullptr ? JavaThreadStatus::NEW : java_lang_Thread::get_thread_status(threadObj); _is_suspended = thread->is_suspended(); _is_in_native = (thread->thread_state() == _thread_in_native); Handle obj = ThreadService::get_current_contended_monitor(thread); oop blocker_object = nullptr; oop blocker_object_owner = nullptr; if (thread->is_vthread_mounted() && thread->vthread() != threadObj) { // ThreadSnapshot only captures platform threads _thread_status = JavaThreadStatus::IN_OBJECT_WAIT; oop vthread = thread->vthread(); assert(vthread != nullptr, ""); blocker_object = vthread; blocker_object_owner = vthread; } else if (_thread_status == JavaThreadStatus::BLOCKED_ON_MONITOR_ENTER || _thread_status == JavaThreadStatus::IN_OBJECT_WAIT || _thread_status == JavaThreadStatus::IN_OBJECT_WAIT_TIMED) { if (obj() == nullptr) { // monitor no longer exists; thread is not blocked _thread_status = JavaThreadStatus::RUNNABLE; } else { blocker_object = obj(); JavaThread* owner = ObjectSynchronizer::get_lock_owner(t_list, obj); if ((owner == nullptr && _thread_status == JavaThreadStatus::BLOCKED_ON_MONITOR_ENTER) || (owner != nullptr && owner->is_attaching_via_jni())) { // ownership information of the monitor is not available // (may no longer be owned or releasing to some other thread) // make this thread in RUNNABLE state. // And when the owner thread is in attaching state, the java thread // is not completely initialized. For example thread name and id // and may not be set, so hide the attaching thread. _thread_status = JavaThreadStatus::RUNNABLE; blocker_object = nullptr; } else if (owner != nullptr) { blocker_object_owner = owner->threadObj(); } } } else if (_thread_status == JavaThreadStatus::PARKED || _thread_status == JavaThreadStatus::PARKED_TIMED) { blocker_object = thread->current_park_blocker(); if (blocker_object != nullptr && blocker_object->is_a(vmClasses::java_util_concurrent_locks_AbstractOwnableSynchronizer_klass())) { blocker_object_owner = java_util_concurrent_locks_AbstractOwnableSynchronizer::get_owner_threadObj(blocker_object); } } if (blocker_object != nullptr) { _blocker_object = OopHandle(_thread_service_storage, blocker_object); } if (blocker_object_owner != nullptr) { _blocker_object_owner = OopHandle(_thread_service_storage, blocker_object_owner); } } oop ThreadSnapshot::blocker_object() const { return _blocker_object.resolve(); } oop ThreadSnapshot::blocker_object_owner() const { return _blocker_object_owner.resolve(); } ThreadSnapshot::~ThreadSnapshot() { _blocker_object.release(_thread_service_storage); _blocker_object_owner.release(_thread_service_storage); _threadObj.release(_thread_service_storage); delete _stack_trace; delete _concurrent_locks; } void ThreadSnapshot::dump_stack_at_safepoint(int max_depth, bool with_locked_monitors, ObjectMonitorsView* monitors, bool full) { _stack_trace = new ThreadStackTrace(_thread, with_locked_monitors); _stack_trace->dump_stack_at_safepoint(max_depth, monitors, full); } void ThreadSnapshot::metadata_do(void f(Metadata*)) { if (_stack_trace != nullptr) { _stack_trace->metadata_do(f); } } DeadlockCycle::DeadlockCycle() { _threads = new (mtServiceability) GrowableArray(INITIAL_ARRAY_SIZE, mtServiceability); _next = nullptr; } DeadlockCycle::~DeadlockCycle() { delete _threads; } void DeadlockCycle::print_on_with(ThreadsList * t_list, outputStream* st) const { st->cr(); st->print_cr("Found one Java-level deadlock:"); st->print("============================="); JavaThread* currentThread; JvmtiRawMonitor* waitingToLockRawMonitor; oop waitingToLockBlocker; int len = _threads->length(); for (int i = 0; i < len; i++) { currentThread = _threads->at(i); // The ObjectMonitor* can't be async deflated since we are at a safepoint. ObjectMonitor* waitingToLockMonitor = currentThread->current_pending_monitor(); waitingToLockRawMonitor = currentThread->current_pending_raw_monitor(); waitingToLockBlocker = currentThread->current_park_blocker(); st->cr(); st->print_cr("\"%s\":", currentThread->name()); const char* owner_desc = ",\n which is held by"; // Note: As the JVM TI "monitor contended enter" event callback is executed after ObjectMonitor // sets the current pending monitor, it is possible to then see a pending raw monitor as well. if (waitingToLockRawMonitor != nullptr) { st->print(" waiting to lock JVM TI raw monitor " INTPTR_FORMAT, p2i(waitingToLockRawMonitor)); Thread* owner = waitingToLockRawMonitor->owner(); // Could be null as the raw monitor could be released at any time if held by non-JavaThread if (owner != nullptr) { if (owner->is_Java_thread()) { currentThread = JavaThread::cast(owner); st->print_cr("%s \"%s\"", owner_desc, currentThread->name()); } else { st->print_cr(",\n which has now been released"); } } else { st->print_cr("%s non-Java thread=" PTR_FORMAT, owner_desc, p2i(owner)); } } if (waitingToLockMonitor != nullptr) { st->print(" waiting to lock monitor " INTPTR_FORMAT, p2i(waitingToLockMonitor)); oop obj = waitingToLockMonitor->object(); st->print(" (object " INTPTR_FORMAT ", a %s)", p2i(obj), obj->klass()->external_name()); if (!currentThread->current_pending_monitor_is_from_java()) { owner_desc = "\n in JNI, which is held by"; } currentThread = Threads::owning_thread_from_monitor(t_list, waitingToLockMonitor); if (currentThread == nullptr) { // The deadlock was detected at a safepoint so the JavaThread // that owns waitingToLockMonitor should be findable, but // if it is not findable, then the previous currentThread is // blocked permanently. st->print_cr("%s UNKNOWN_owner_addr=" INT64_FORMAT, owner_desc, waitingToLockMonitor->owner()); continue; } } else { st->print(" waiting for ownable synchronizer " INTPTR_FORMAT ", (a %s)", p2i(waitingToLockBlocker), waitingToLockBlocker->klass()->external_name()); assert(waitingToLockBlocker->is_a(vmClasses::java_util_concurrent_locks_AbstractOwnableSynchronizer_klass()), "Must be an AbstractOwnableSynchronizer"); oop ownerObj = java_util_concurrent_locks_AbstractOwnableSynchronizer::get_owner_threadObj(waitingToLockBlocker); currentThread = java_lang_Thread::thread(ownerObj); assert(currentThread != nullptr, "AbstractOwnableSynchronizer owning thread is unexpectedly null"); } st->print_cr("%s \"%s\"", owner_desc, currentThread->name()); } st->cr(); // Print stack traces bool oldJavaMonitorsInStackTrace = JavaMonitorsInStackTrace; JavaMonitorsInStackTrace = true; st->print_cr("Java stack information for the threads listed above:"); st->print_cr("==================================================="); for (int j = 0; j < len; j++) { currentThread = _threads->at(j); st->print_cr("\"%s\":", currentThread->name()); currentThread->print_stack_on(st); } JavaMonitorsInStackTrace = oldJavaMonitorsInStackTrace; } ThreadsListEnumerator::ThreadsListEnumerator(Thread* cur_thread, bool include_jvmti_agent_threads, bool include_jni_attaching_threads, bool include_bound_virtual_threads) { assert(cur_thread == Thread::current(), "Check current thread"); int init_size = ThreadService::get_live_thread_count(); _threads_array = new GrowableArray(init_size); for (JavaThreadIteratorWithHandle jtiwh; JavaThread *jt = jtiwh.next(); ) { // skips JavaThreads in the process of exiting // and also skips VM internal JavaThreads // Threads in _thread_new or _thread_new_trans state are included. // i.e. threads have been started but not yet running. if (jt->threadObj() == nullptr || jt->is_exiting() || !java_lang_Thread::is_alive(jt->threadObj()) || jt->is_hidden_from_external_view()) { continue; } // skip agent threads if (!include_jvmti_agent_threads && jt->is_jvmti_agent_thread()) { continue; } // skip jni threads in the process of attaching if (!include_jni_attaching_threads && jt->is_attaching_via_jni()) { continue; } // skip instances of BoundVirtualThread if (!include_bound_virtual_threads && jt->threadObj()->is_a(vmClasses::BoundVirtualThread_klass())) { continue; } instanceHandle h(cur_thread, (instanceOop) jt->threadObj()); _threads_array->append(h); } } // jdk.internal.vm.ThreadSnapshot support #if INCLUDE_JVMTI class GetThreadSnapshotClosure: public HandshakeClosure { private: static OopStorage* oop_storage() { assert(_thread_service_storage != nullptr, "sanity"); return _thread_service_storage; } public: struct OwnedLock { // should be synced with ordinals of jdk.internal.vm.ThreadSnapshot.OwnedLockType enum enum Type { NOTHING = -1, LOCKED = 0, ELIMINATED = 1, }; int _frame_depth; Type _type; // synchronization object (when type == LOCKED) or its klass (type == ELIMINATED) OopHandle _obj; OwnedLock(int depth, Type type, OopHandle obj): _frame_depth(depth), _type(type), _obj(obj) {} OwnedLock(): _frame_depth(0), _type(NOTHING), _obj(nullptr) {} }; struct Blocker { // should be synced with ordinals of jdk.internal.vm.ThreadSnapshot.BlockerLockType enum enum Type { NOTHING = -1, PARK_BLOCKER = 0, WAITING_TO_LOCK = 1, WAITING_ON = 2, }; Type _type; // park blocker or an object the thread waiting on/trying to lock OopHandle _obj; Blocker(Type type, OopHandle obj): _type(type), _obj(obj) {} Blocker(): _type(NOTHING), _obj(nullptr) {} bool is_empty() const { return _type == NOTHING; } }; Handle _thread_h; JavaThread* _java_thread; int _frame_count; // length of _methods and _bcis arrays GrowableArray* _methods; GrowableArray* _bcis; JavaThreadStatus _thread_status; OopHandle _thread_name; GrowableArray* _locks; Blocker _blocker; GetThreadSnapshotClosure(Handle thread_h, JavaThread* java_thread): HandshakeClosure("GetThreadSnapshotClosure"), _thread_h(thread_h), _java_thread(java_thread), _frame_count(0), _methods(nullptr), _bcis(nullptr), _thread_status(), _thread_name(nullptr), _locks(nullptr), _blocker() { } virtual ~GetThreadSnapshotClosure() { delete _methods; delete _bcis; _thread_name.release(oop_storage()); if (_locks != nullptr) { for (int i = 0; i < _locks->length(); i++) { _locks->at(i)._obj.release(oop_storage()); } delete _locks; } _blocker._obj.release(oop_storage()); } private: void detect_locks(javaVFrame* jvf, int depth) { Thread* current = Thread::current(); if (depth == 0 && _blocker.is_empty()) { // If this is the first frame and it is java.lang.Object.wait(...) // then print out the receiver. if (jvf->method()->name() == vmSymbols::wait_name() && jvf->method()->method_holder()->name() == vmSymbols::java_lang_Object()) { OopHandle lock_object; StackValueCollection* locs = jvf->locals(); if (!locs->is_empty()) { StackValue* sv = locs->at(0); if (sv->type() == T_OBJECT) { Handle o = locs->at(0)->get_obj(); lock_object = OopHandle(oop_storage(), o()); } } _blocker = Blocker(Blocker::WAITING_ON, lock_object); } } GrowableArray* mons = jvf->monitors(); if (!mons->is_empty()) { for (int index = (mons->length() - 1); index >= 0; index--) { MonitorInfo* monitor = mons->at(index); if (monitor->eliminated() && jvf->is_compiled_frame()) { // Eliminated in compiled code if (monitor->owner_is_scalar_replaced()) { Klass* k = java_lang_Class::as_Klass(monitor->owner_klass()); _locks->push(OwnedLock(depth, OwnedLock::ELIMINATED, OopHandle(oop_storage(), k->klass_holder()))); } else { Handle owner(current, monitor->owner()); if (owner.not_null()) { Klass* k = owner->klass(); _locks->push(OwnedLock(depth, OwnedLock::ELIMINATED, OopHandle(oop_storage(), k->klass_holder()))); } } continue; } if (monitor->owner() != nullptr) { // the monitor is associated with an object, i.e., it is locked if (depth == 0 && _blocker.is_empty()) { ObjectMonitor* pending_moninor = java_lang_VirtualThread::is_instance(_thread_h()) ? java_lang_VirtualThread::current_pending_monitor(_thread_h()) : jvf->thread()->current_pending_monitor(); markWord mark = monitor->owner()->mark(); // The first stage of async deflation does not affect any field // used by this comparison so the ObjectMonitor* is usable here. if (mark.has_monitor()) { ObjectMonitor* mon = ObjectSynchronizer::read_monitor(current, monitor->owner(), mark); if (// if the monitor is null we must be in the process of locking mon == nullptr || // we have marked ourself as pending on this monitor mon == pending_moninor || // we are not the owner of this monitor (_java_thread != nullptr && !mon->is_entered(_java_thread))) { _blocker = Blocker(Blocker::WAITING_TO_LOCK, OopHandle(oop_storage(), monitor->owner())); continue; // go to next monitor } } } _locks->push(OwnedLock(depth, OwnedLock::LOCKED, OopHandle(oop_storage(), monitor->owner()))); } } } } public: void do_thread(Thread* th) override { Thread* current = Thread::current(); bool is_virtual = java_lang_VirtualThread::is_instance(_thread_h()); if (_java_thread != nullptr) { if (is_virtual) { // mounted vthread, use carrier thread state oop carrier_thread = java_lang_VirtualThread::carrier_thread(_thread_h()); _thread_status = java_lang_Thread::get_thread_status(carrier_thread); } else { _thread_status = java_lang_Thread::get_thread_status(_thread_h()); } } else { // unmounted vthread int vt_state = java_lang_VirtualThread::state(_thread_h()); _thread_status = java_lang_VirtualThread::map_state_to_thread_status(vt_state); } _thread_name = OopHandle(oop_storage(), java_lang_Thread::name(_thread_h())); if (_java_thread != nullptr && !_java_thread->has_last_Java_frame()) { // stack trace is empty return; } bool vthread_carrier = !is_virtual && (_java_thread != nullptr) && (_java_thread->vthread_continuation() != nullptr); oop park_blocker = java_lang_Thread::park_blocker(_thread_h()); if (park_blocker != nullptr) { _blocker = Blocker(Blocker::PARK_BLOCKER, OopHandle(oop_storage(), park_blocker)); } ResourceMark rm(current); HandleMark hm(current); const int max_depth = MaxJavaStackTraceDepth; const bool skip_hidden = !ShowHiddenFrames; // Pick minimum length that will cover most cases int init_length = 64; _methods = new (mtInternal) GrowableArray(init_length, mtInternal); _bcis = new (mtInternal) GrowableArray(init_length, mtInternal); _locks = new (mtInternal) GrowableArray(init_length, mtInternal); int total_count = 0; vframeStream vfst(_java_thread != nullptr ? vframeStream(_java_thread, false, true, vthread_carrier) : vframeStream(java_lang_VirtualThread::continuation(_thread_h()))); for (; !vfst.at_end() && (max_depth == 0 || max_depth != total_count); vfst.next()) { detect_locks(vfst.asJavaVFrame(), total_count); if (skip_hidden && (vfst.method()->is_hidden() || vfst.method()->is_continuation_enter_intrinsic())) { continue; } _methods->push(vfst.method()); _bcis->push(vfst.bci()); total_count++; } _frame_count = total_count; } }; class jdk_internal_vm_ThreadLock: AllStatic { static bool _inited; static int _depth_offset; static int _typeOrdinal_offset; static int _obj_offset; static void compute_offsets(InstanceKlass* klass, TRAPS) { JavaClasses::compute_offset(_depth_offset, klass, "depth", vmSymbols::int_signature(), false); JavaClasses::compute_offset(_typeOrdinal_offset, klass, "typeOrdinal", vmSymbols::int_signature(), false); JavaClasses::compute_offset(_obj_offset, klass, "obj", vmSymbols::object_signature(), false); } public: static void init(InstanceKlass* klass, TRAPS) { if (!_inited) { compute_offsets(klass, CHECK); _inited = true; } } static Handle create(InstanceKlass* klass, int depth, int type_ordinal, OopHandle obj, TRAPS) { init(klass, CHECK_NH); Handle result = klass->allocate_instance_handle(CHECK_NH); result->int_field_put(_depth_offset, depth); result->int_field_put(_typeOrdinal_offset, type_ordinal); result->obj_field_put(_obj_offset, obj.resolve()); return result; } }; bool jdk_internal_vm_ThreadLock::_inited = false; int jdk_internal_vm_ThreadLock::_depth_offset; int jdk_internal_vm_ThreadLock::_typeOrdinal_offset; int jdk_internal_vm_ThreadLock::_obj_offset; class jdk_internal_vm_ThreadSnapshot: AllStatic { static bool _inited; static int _name_offset; static int _threadStatus_offset; static int _carrierThread_offset; static int _stackTrace_offset; static int _locks_offset; static int _blockerTypeOrdinal_offset; static int _blockerObject_offset; static void compute_offsets(InstanceKlass* klass, TRAPS) { JavaClasses::compute_offset(_name_offset, klass, "name", vmSymbols::string_signature(), false); JavaClasses::compute_offset(_threadStatus_offset, klass, "threadStatus", vmSymbols::int_signature(), false); JavaClasses::compute_offset(_carrierThread_offset, klass, "carrierThread", vmSymbols::thread_signature(), false); JavaClasses::compute_offset(_stackTrace_offset, klass, "stackTrace", vmSymbols::java_lang_StackTraceElement_array(), false); JavaClasses::compute_offset(_locks_offset, klass, "locks", vmSymbols::jdk_internal_vm_ThreadLock_array(), false); JavaClasses::compute_offset(_blockerTypeOrdinal_offset, klass, "blockerTypeOrdinal", vmSymbols::int_signature(), false); JavaClasses::compute_offset(_blockerObject_offset, klass, "blockerObject", vmSymbols::object_signature(), false); } public: static void init(InstanceKlass* klass, TRAPS) { if (!_inited) { compute_offsets(klass, CHECK); _inited = true; } } static Handle allocate(InstanceKlass* klass, TRAPS) { init(klass, CHECK_NH); Handle h_k = klass->allocate_instance_handle(CHECK_NH); return h_k; } static void set_name(oop snapshot, oop name) { snapshot->obj_field_put(_name_offset, name); } static void set_thread_status(oop snapshot, int status) { snapshot->int_field_put(_threadStatus_offset, status); } static void set_carrier_thread(oop snapshot, oop carrier_thread) { snapshot->obj_field_put(_carrierThread_offset, carrier_thread); } static void set_stack_trace(oop snapshot, oop trace) { snapshot->obj_field_put(_stackTrace_offset, trace); } static void set_locks(oop snapshot, oop locks) { snapshot->obj_field_put(_locks_offset, locks); } static void set_blocker(oop snapshot, int type_ordinal, oop lock) { snapshot->int_field_put(_blockerTypeOrdinal_offset, type_ordinal); snapshot->obj_field_put(_blockerObject_offset, lock); } }; bool jdk_internal_vm_ThreadSnapshot::_inited = false; int jdk_internal_vm_ThreadSnapshot::_name_offset; int jdk_internal_vm_ThreadSnapshot::_threadStatus_offset; int jdk_internal_vm_ThreadSnapshot::_carrierThread_offset; int jdk_internal_vm_ThreadSnapshot::_stackTrace_offset; int jdk_internal_vm_ThreadSnapshot::_locks_offset; int jdk_internal_vm_ThreadSnapshot::_blockerTypeOrdinal_offset; int jdk_internal_vm_ThreadSnapshot::_blockerObject_offset; oop ThreadSnapshotFactory::get_thread_snapshot(jobject jthread, TRAPS) { ThreadsListHandle tlh(THREAD); ResourceMark rm(THREAD); HandleMark hm(THREAD); Handle thread_h(THREAD, JNIHandles::resolve(jthread)); // wrapper to auto delete JvmtiVTMSTransitionDisabler class TransitionDisabler { JvmtiVTMSTransitionDisabler* _transition_disabler; public: TransitionDisabler(): _transition_disabler(nullptr) {} ~TransitionDisabler() { reset(); } void init(jobject jthread) { _transition_disabler = new (mtInternal) JvmtiVTMSTransitionDisabler(jthread); } void reset() { if (_transition_disabler != nullptr) { delete _transition_disabler; _transition_disabler = nullptr; } } } transition_disabler; JavaThread* java_thread = nullptr; bool is_virtual = java_lang_VirtualThread::is_instance(thread_h()); Handle carrier_thread; if (is_virtual) { // 1st need to disable mount/unmount transitions transition_disabler.init(jthread); carrier_thread = Handle(THREAD, java_lang_VirtualThread::carrier_thread(thread_h())); if (carrier_thread != nullptr) { java_thread = java_lang_Thread::thread(carrier_thread()); } } else { java_thread = java_lang_Thread::thread(thread_h()); } // Handshake with target GetThreadSnapshotClosure cl(thread_h, java_thread); if (java_thread == nullptr) { // unmounted vthread, execute on the current thread cl.do_thread(nullptr); } else { Handshake::execute(&cl, &tlh, java_thread); } // all info is collected, can enable transitions. transition_disabler.reset(); // StackTrace InstanceKlass* ste_klass = vmClasses::StackTraceElement_klass(); assert(ste_klass != nullptr, "must be loaded"); objArrayHandle trace = oopFactory::new_objArray_handle(ste_klass, cl._frame_count, CHECK_NULL); for (int i = 0; i < cl._frame_count; i++) { methodHandle method(THREAD, cl._methods->at(i)); oop element = java_lang_StackTraceElement::create(method, cl._bcis->at(i), CHECK_NULL); trace->obj_at_put(i, element); } // Locks Symbol* lock_sym = vmSymbols::jdk_internal_vm_ThreadLock(); Klass* lock_k = SystemDictionary::resolve_or_fail(lock_sym, true, CHECK_NULL); InstanceKlass* lock_klass = InstanceKlass::cast(lock_k); objArrayHandle locks; if (cl._locks != nullptr && cl._locks->length() > 0) { locks = oopFactory::new_objArray_handle(lock_klass, cl._locks->length(), CHECK_NULL); for (int n = 0; n < cl._locks->length(); n++) { GetThreadSnapshotClosure::OwnedLock* lock_info = cl._locks->adr_at(n); Handle lock = jdk_internal_vm_ThreadLock::create(lock_klass, lock_info->_frame_depth, lock_info->_type, lock_info->_obj, CHECK_NULL); locks->obj_at_put(n, lock()); } } // call static StackTraceElement[] StackTraceElement.of(StackTraceElement[] stackTrace) // to properly initialize STEs. JavaValue result(T_OBJECT); JavaCalls::call_static(&result, ste_klass, vmSymbols::java_lang_StackTraceElement_of_name(), vmSymbols::java_lang_StackTraceElement_of_signature(), trace, CHECK_NULL); // the method return the same trace array Symbol* snapshot_klass_name = vmSymbols::jdk_internal_vm_ThreadSnapshot(); Klass* snapshot_klass = SystemDictionary::resolve_or_fail(snapshot_klass_name, true, CHECK_NULL); if (snapshot_klass->should_be_initialized()) { snapshot_klass->initialize(CHECK_NULL); } Handle snapshot = jdk_internal_vm_ThreadSnapshot::allocate(InstanceKlass::cast(snapshot_klass), CHECK_NULL); jdk_internal_vm_ThreadSnapshot::set_name(snapshot(), cl._thread_name.resolve()); jdk_internal_vm_ThreadSnapshot::set_thread_status(snapshot(), (int)cl._thread_status); jdk_internal_vm_ThreadSnapshot::set_carrier_thread(snapshot(), carrier_thread()); jdk_internal_vm_ThreadSnapshot::set_stack_trace(snapshot(), trace()); jdk_internal_vm_ThreadSnapshot::set_locks(snapshot(), locks()); if (!cl._blocker.is_empty()) { jdk_internal_vm_ThreadSnapshot::set_blocker(snapshot(), cl._blocker._type, cl._blocker._obj.resolve()); } return snapshot(); } #endif // INCLUDE_JVMTI