/* * Copyright (c) 2011, 2025, Oracle and/or its affiliates. All rights reserved. * Copyright (c) 2017, 2021 SAP SE. All rights reserved. * Copyright (c) 2023, 2025, Red Hat, Inc. 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 "cds/cdsConfig.hpp" #include "cds/metaspaceShared.hpp" #include "classfile/classLoaderData.hpp" #include "gc/shared/collectedHeap.hpp" #include "logging/log.hpp" #include "logging/logStream.hpp" #include "memory/classLoaderMetaspace.hpp" #include "memory/memoryReserver.hpp" #include "memory/metaspace.hpp" #include "memory/metaspace/chunkHeaderPool.hpp" #include "memory/metaspace/chunkManager.hpp" #include "memory/metaspace/commitLimiter.hpp" #include "memory/metaspace/internalStats.hpp" #include "memory/metaspace/metachunk.hpp" #include "memory/metaspace/metaspaceCommon.hpp" #include "memory/metaspace/metaspaceContext.hpp" #include "memory/metaspace/metaspaceReporter.hpp" #include "memory/metaspace/metaspaceSettings.hpp" #include "memory/metaspace/runningCounters.hpp" #include "memory/metaspace/virtualSpaceList.hpp" #include "memory/metaspaceCriticalAllocation.hpp" #include "memory/metaspaceStats.hpp" #include "memory/metaspaceTracer.hpp" #include "memory/metaspaceUtils.hpp" #include "memory/resourceArea.hpp" #include "memory/universe.hpp" #include "nmt/memTracker.hpp" #include "oops/compressedKlass.inline.hpp" #include "oops/compressedOops.hpp" #include "prims/jvmtiExport.hpp" #include "runtime/atomic.hpp" #include "runtime/globals_extension.hpp" #include "runtime/init.hpp" #include "runtime/java.hpp" #include "runtime/mutexLocker.hpp" #include "utilities/copy.hpp" #include "utilities/debug.hpp" #include "utilities/formatBuffer.hpp" #include "utilities/globalDefinitions.hpp" #include "utilities/ostream.hpp" using metaspace::ChunkManager; using metaspace::CommitLimiter; using metaspace::MetaspaceContext; using metaspace::MetaspaceReporter; using metaspace::RunningCounters; using metaspace::VirtualSpaceList; size_t MetaspaceUtils::used_words() { return RunningCounters::used_words(); } size_t MetaspaceUtils::used_words(Metaspace::MetadataType mdtype) { return mdtype == Metaspace::ClassType ? RunningCounters::used_words_class() : RunningCounters::used_words_nonclass(); } size_t MetaspaceUtils::reserved_words() { return RunningCounters::reserved_words(); } size_t MetaspaceUtils::reserved_words(Metaspace::MetadataType mdtype) { return mdtype == Metaspace::ClassType ? RunningCounters::reserved_words_class() : RunningCounters::reserved_words_nonclass(); } size_t MetaspaceUtils::committed_words() { return RunningCounters::committed_words(); } size_t MetaspaceUtils::committed_words(Metaspace::MetadataType mdtype) { return mdtype == Metaspace::ClassType ? RunningCounters::committed_words_class() : RunningCounters::committed_words_nonclass(); } // Helper for get_statistics() static void get_values_for(Metaspace::MetadataType mdtype, size_t* reserved, size_t* committed, size_t* used) { #define w2b(x) (x * sizeof(MetaWord)) if (mdtype == Metaspace::ClassType) { *reserved = w2b(RunningCounters::reserved_words_class()); *committed = w2b(RunningCounters::committed_words_class()); *used = w2b(RunningCounters::used_words_class()); } else { *reserved = w2b(RunningCounters::reserved_words_nonclass()); *committed = w2b(RunningCounters::committed_words_nonclass()); *used = w2b(RunningCounters::used_words_nonclass()); } #undef w2b } // Retrieve all statistics in one go; make sure the values are consistent. MetaspaceStats MetaspaceUtils::get_statistics(Metaspace::MetadataType mdtype) { // Consistency: // This function reads three values (reserved, committed, used) from different counters. These counters // may (very rarely) be out of sync. This has been a source for intermittent test errors in the past // (see e.g. JDK-8237872, JDK-8151460). // - reserved and committed counter are updated under protection of Metaspace_lock; an inconsistency // between them can be the result of a dirty read. // - used is an atomic counter updated outside any lock range; there is no way to guarantee // a clean read wrt the other two values. // Reading these values under lock protection would would only help for the first case. Therefore // we don't bother and just re-read several times, then give up and correct the values. size_t r = 0, c = 0, u = 0; // Note: byte values. get_values_for(mdtype, &r, &c, &u); int retries = 10; // If the first retrieval resulted in inconsistent values, retry a bit... while ((r < c || c < u) && --retries >= 0) { get_values_for(mdtype, &r, &c, &u); } if (c < u || r < c) { // still inconsistent. // ... but not endlessly. If we don't get consistent values, correct them on the fly. // The logic here is that we trust the used counter - its an atomic counter and whatever we see // must have been the truth once - and from that we reconstruct a likely set of committed/reserved // values. metaspace::InternalStats::inc_num_inconsistent_stats(); if (c < u) { c = align_up(u, Metaspace::commit_alignment()); } if (r < c) { r = align_up(c, Metaspace::reserve_alignment()); } } return MetaspaceStats(r, c, u); } MetaspaceCombinedStats MetaspaceUtils::get_combined_statistics() { return MetaspaceCombinedStats(get_statistics(Metaspace::ClassType), get_statistics(Metaspace::NonClassType)); } void MetaspaceUtils::print_metaspace_change(const MetaspaceCombinedStats& pre_meta_values) { // Get values now: const MetaspaceCombinedStats meta_values = get_combined_statistics(); // We print used and committed since these are the most useful at-a-glance vitals for Metaspace: // - used tells you how much memory is actually used for metadata // - committed tells you how much memory is committed for the purpose of metadata // The difference between those two would be waste, which can have various forms (freelists, // unused parts of committed chunks etc) // // Left out is reserved, since this is not as exciting as the first two values: for class space, // it is a constant (to uninformed users, often confusingly large). For non-class space, it would // be interesting since free chunks can be uncommitted, but for now it is left out. if (Metaspace::using_class_space()) { log_info(gc, metaspace)(HEAP_CHANGE_FORMAT" " HEAP_CHANGE_FORMAT" " HEAP_CHANGE_FORMAT, HEAP_CHANGE_FORMAT_ARGS("Metaspace", pre_meta_values.used(), pre_meta_values.committed(), meta_values.used(), meta_values.committed()), HEAP_CHANGE_FORMAT_ARGS("NonClass", pre_meta_values.non_class_used(), pre_meta_values.non_class_committed(), meta_values.non_class_used(), meta_values.non_class_committed()), HEAP_CHANGE_FORMAT_ARGS("Class", pre_meta_values.class_used(), pre_meta_values.class_committed(), meta_values.class_used(), meta_values.class_committed())); } else { log_info(gc, metaspace)(HEAP_CHANGE_FORMAT, HEAP_CHANGE_FORMAT_ARGS("Metaspace", pre_meta_values.used(), pre_meta_values.committed(), meta_values.used(), meta_values.committed())); } } // This will print out a basic metaspace usage report but // unlike print_report() is guaranteed not to lock or to walk the CLDG. void MetaspaceUtils::print_basic_report(outputStream* out, size_t scale) { MetaspaceReporter::print_basic_report(out, scale); } // Prints a report about the current metaspace state. // Optional parts can be enabled via flags. // Function will walk the CLDG and will lock the expand lock; if that is not // convenient, use print_basic_report() instead. void MetaspaceUtils::print_report(outputStream* out, size_t scale) { const int flags = (int)MetaspaceReporter::Option::ShowLoaders | (int)MetaspaceReporter::Option::BreakDownByChunkType | (int)MetaspaceReporter::Option::ShowClasses; MetaspaceReporter::print_report(out, scale, flags); } void MetaspaceUtils::print_on(outputStream* out) { // First prints out totals, then, separately, the class space portion. MetaspaceCombinedStats stats = get_combined_statistics(); out->print("Metaspace "); out->fill_to(17); out->print_cr("used %zuK, " "committed %zuK, " "reserved %zuK", stats.used()/K, stats.committed()/K, stats.reserved()/K); if (Metaspace::using_class_space()) { StreamIndentor si(out, 1); out->print("class space "); out->fill_to(17); out->print_cr("used %zuK, " "committed %zuK, " "reserved %zuK", stats.class_space_stats().used()/K, stats.class_space_stats().committed()/K, stats.class_space_stats().reserved()/K); } } #ifdef ASSERT void MetaspaceUtils::verify() { if (Metaspace::initialized()) { // Verify non-class chunkmanager... ChunkManager* cm = ChunkManager::chunkmanager_nonclass(); cm->verify(); // ... and space list. VirtualSpaceList* vsl = VirtualSpaceList::vslist_nonclass(); vsl->verify(); if (Metaspace::using_class_space()) { // If we use compressed class pointers, verify class chunkmanager... cm = ChunkManager::chunkmanager_class(); cm->verify(); // ... and class spacelist. vsl = VirtualSpaceList::vslist_class(); vsl->verify(); } } } #endif ////////////////////////////////7 // MetaspaceGC methods volatile size_t MetaspaceGC::_capacity_until_GC = 0; uint MetaspaceGC::_shrink_factor = 0; // VM_CollectForMetadataAllocation is the vm operation used to GC. // Within the VM operation after the GC the attempt to allocate the metadata // should succeed. If the GC did not free enough space for the metaspace // allocation, the HWM is increased so that another virtualspace will be // allocated for the metadata. With perm gen the increase in the perm // gen had bounds, MinMetaspaceExpansion and MaxMetaspaceExpansion. The // metaspace policy uses those as the small and large steps for the HWM. // // After the GC the compute_new_size() for MetaspaceGC is called to // resize the capacity of the metaspaces. The current implementation // is based on the flags MinMetaspaceFreeRatio and MaxMetaspaceFreeRatio used // to resize the Java heap by some GC's. New flags can be implemented // if really needed. MinMetaspaceFreeRatio is used to calculate how much // free space is desirable in the metaspace capacity to decide how much // to increase the HWM. MaxMetaspaceFreeRatio is used to decide how much // free space is desirable in the metaspace capacity before decreasing // the HWM. // Calculate the amount to increase the high water mark (HWM). // Increase by a minimum amount (MinMetaspaceExpansion) so that // another expansion is not requested too soon. If that is not // enough to satisfy the allocation, increase by MaxMetaspaceExpansion. // If that is still not enough, expand by the size of the allocation // plus some. size_t MetaspaceGC::delta_capacity_until_GC(size_t bytes) { size_t min_delta = MinMetaspaceExpansion; size_t max_delta = MaxMetaspaceExpansion; size_t delta = align_up(bytes, Metaspace::commit_alignment()); if (delta <= min_delta) { delta = min_delta; } else if (delta <= max_delta) { // Don't want to hit the high water mark on the next // allocation so make the delta greater than just enough // for this allocation. delta = max_delta; } else { // This allocation is large but the next ones are probably not // so increase by the minimum. delta = delta + min_delta; } assert_is_aligned(delta, Metaspace::commit_alignment()); return delta; } size_t MetaspaceGC::capacity_until_GC() { size_t value = Atomic::load_acquire(&_capacity_until_GC); assert(value >= MetaspaceSize, "Not initialized properly?"); return value; } // Try to increase the _capacity_until_GC limit counter by v bytes. // Returns true if it succeeded. It may fail if either another thread // concurrently increased the limit or the new limit would be larger // than MaxMetaspaceSize. // On success, optionally returns new and old metaspace capacity in // new_cap_until_GC and old_cap_until_GC respectively. // On error, optionally sets can_retry to indicate whether if there is // actually enough space remaining to satisfy the request. bool MetaspaceGC::inc_capacity_until_GC(size_t v, size_t* new_cap_until_GC, size_t* old_cap_until_GC, bool* can_retry) { assert_is_aligned(v, Metaspace::commit_alignment()); size_t old_capacity_until_GC = _capacity_until_GC; size_t new_value = old_capacity_until_GC + v; if (new_value < old_capacity_until_GC) { // The addition wrapped around, set new_value to aligned max value. new_value = align_down(max_uintx, Metaspace::reserve_alignment()); } if (new_value > MaxMetaspaceSize) { if (can_retry != nullptr) { *can_retry = false; } return false; } if (can_retry != nullptr) { *can_retry = true; } size_t prev_value = Atomic::cmpxchg(&_capacity_until_GC, old_capacity_until_GC, new_value); if (old_capacity_until_GC != prev_value) { return false; } if (new_cap_until_GC != nullptr) { *new_cap_until_GC = new_value; } if (old_cap_until_GC != nullptr) { *old_cap_until_GC = old_capacity_until_GC; } return true; } size_t MetaspaceGC::dec_capacity_until_GC(size_t v) { assert_is_aligned(v, Metaspace::commit_alignment()); return Atomic::sub(&_capacity_until_GC, v); } void MetaspaceGC::initialize() { // Set the high-water mark to MaxMetapaceSize during VM initializaton since // we can't do a GC during initialization. _capacity_until_GC = MaxMetaspaceSize; } void MetaspaceGC::post_initialize() { // Reset the high-water mark once the VM initialization is done. _capacity_until_GC = MAX2(MetaspaceUtils::committed_bytes(), MetaspaceSize); } bool MetaspaceGC::can_expand(size_t word_size, bool is_class) { // Check if the compressed class space is full. if (is_class && Metaspace::using_class_space()) { size_t class_committed = MetaspaceUtils::committed_bytes(Metaspace::ClassType); if (class_committed + word_size * BytesPerWord > CompressedClassSpaceSize) { log_trace(gc, metaspace, freelist)("Cannot expand %s metaspace by %zu words (CompressedClassSpaceSize = %zu words)", (is_class ? "class" : "non-class"), word_size, CompressedClassSpaceSize / sizeof(MetaWord)); return false; } } // Check if the user has imposed a limit on the metaspace memory. size_t committed_bytes = MetaspaceUtils::committed_bytes(); if (committed_bytes + word_size * BytesPerWord > MaxMetaspaceSize) { log_trace(gc, metaspace, freelist)("Cannot expand %s metaspace by %zu words (MaxMetaspaceSize = %zu words)", (is_class ? "class" : "non-class"), word_size, MaxMetaspaceSize / sizeof(MetaWord)); return false; } return true; } size_t MetaspaceGC::allowed_expansion() { size_t committed_bytes = MetaspaceUtils::committed_bytes(); size_t capacity_until_gc = capacity_until_GC(); size_t left_until_max = MaxMetaspaceSize - committed_bytes; // capacity_until_GC may have been decreased concurrently and may // temporarily be lower than what metaspace has committed. Allow for that. size_t left_until_GC = capacity_until_gc > committed_bytes ? capacity_until_gc - committed_bytes : 0; size_t left_to_commit = MIN2(left_until_GC, left_until_max); log_trace(gc, metaspace, freelist)("allowed expansion words: %zu" " (left_until_max: %zu, left_until_GC: %zu.", left_to_commit / BytesPerWord, left_until_max / BytesPerWord, left_until_GC / BytesPerWord); return left_to_commit / BytesPerWord; } void MetaspaceGC::compute_new_size() { assert(_shrink_factor <= 100, "invalid shrink factor"); uint current_shrink_factor = _shrink_factor; _shrink_factor = 0; // Using committed_bytes() for used_after_gc is an overestimation, since the // chunk free lists are included in committed_bytes() and the memory in an // un-fragmented chunk free list is available for future allocations. // However, if the chunk free lists becomes fragmented, then the memory may // not be available for future allocations and the memory is therefore "in use". // Including the chunk free lists in the definition of "in use" is therefore // necessary. Not including the chunk free lists can cause capacity_until_GC to // shrink below committed_bytes() and this has caused serious bugs in the past. const double used_after_gc = (double)MetaspaceUtils::committed_bytes(); const size_t capacity_until_GC = MetaspaceGC::capacity_until_GC(); const double minimum_free_percentage = MinMetaspaceFreeRatio / 100.0; const double maximum_used_percentage = 1.0 - minimum_free_percentage; const double min_tmp = used_after_gc / maximum_used_percentage; size_t minimum_desired_capacity = (size_t)MIN2(min_tmp, double(MaxMetaspaceSize)); // Don't shrink less than the initial generation size minimum_desired_capacity = MAX2(minimum_desired_capacity, MetaspaceSize); log_trace(gc, metaspace)("MetaspaceGC::compute_new_size: "); log_trace(gc, metaspace)(" minimum_free_percentage: %6.2f maximum_used_percentage: %6.2f", minimum_free_percentage, maximum_used_percentage); log_trace(gc, metaspace)(" used_after_gc : %6.1fKB", used_after_gc / (double) K); size_t shrink_bytes = 0; if (capacity_until_GC < minimum_desired_capacity) { // If we have less capacity below the metaspace HWM, then // increment the HWM. size_t expand_bytes = minimum_desired_capacity - capacity_until_GC; expand_bytes = align_up(expand_bytes, Metaspace::commit_alignment()); // Don't expand unless it's significant if (expand_bytes >= MinMetaspaceExpansion) { size_t new_capacity_until_GC = 0; bool succeeded = MetaspaceGC::inc_capacity_until_GC(expand_bytes, &new_capacity_until_GC); assert(succeeded, "Should always successfully increment HWM when at safepoint"); Metaspace::tracer()->report_gc_threshold(capacity_until_GC, new_capacity_until_GC, MetaspaceGCThresholdUpdater::ComputeNewSize); log_trace(gc, metaspace)(" expanding: minimum_desired_capacity: %6.1fKB expand_bytes: %6.1fKB MinMetaspaceExpansion: %6.1fKB new metaspace HWM: %6.1fKB", (double) minimum_desired_capacity / (double) K, (double) expand_bytes / (double) K, (double) MinMetaspaceExpansion / (double) K, (double) new_capacity_until_GC / (double) K); } return; } // No expansion, now see if we want to shrink // We would never want to shrink more than this assert(capacity_until_GC >= minimum_desired_capacity, "%zu >= %zu", capacity_until_GC, minimum_desired_capacity); size_t max_shrink_bytes = capacity_until_GC - minimum_desired_capacity; // Should shrinking be considered? if (MaxMetaspaceFreeRatio < 100) { const double maximum_free_percentage = MaxMetaspaceFreeRatio / 100.0; const double minimum_used_percentage = 1.0 - maximum_free_percentage; const double max_tmp = used_after_gc / minimum_used_percentage; size_t maximum_desired_capacity = (size_t)MIN2(max_tmp, double(MaxMetaspaceSize)); maximum_desired_capacity = MAX2(maximum_desired_capacity, MetaspaceSize); log_trace(gc, metaspace)(" maximum_free_percentage: %6.2f minimum_used_percentage: %6.2f", maximum_free_percentage, minimum_used_percentage); log_trace(gc, metaspace)(" minimum_desired_capacity: %6.1fKB maximum_desired_capacity: %6.1fKB", (double) minimum_desired_capacity / (double) K, (double) maximum_desired_capacity / (double) K); assert(minimum_desired_capacity <= maximum_desired_capacity, "sanity check"); if (capacity_until_GC > maximum_desired_capacity) { // Capacity too large, compute shrinking size shrink_bytes = capacity_until_GC - maximum_desired_capacity; // We don't want shrink all the way back to initSize if people call // System.gc(), because some programs do that between "phases" and then // we'd just have to grow the heap up again for the next phase. So we // damp the shrinking: 0% on the first call, 10% on the second call, 40% // on the third call, and 100% by the fourth call. But if we recompute // size without shrinking, it goes back to 0%. shrink_bytes = shrink_bytes / 100 * current_shrink_factor; shrink_bytes = align_down(shrink_bytes, Metaspace::commit_alignment()); assert(shrink_bytes <= max_shrink_bytes, "invalid shrink size %zu not <= %zu", shrink_bytes, max_shrink_bytes); if (current_shrink_factor == 0) { _shrink_factor = 10; } else { _shrink_factor = MIN2(current_shrink_factor * 4, (uint) 100); } log_trace(gc, metaspace)(" shrinking: initThreshold: %.1fK maximum_desired_capacity: %.1fK", (double) MetaspaceSize / (double) K, (double) maximum_desired_capacity / (double) K); log_trace(gc, metaspace)(" shrink_bytes: %.1fK current_shrink_factor: %d new shrink factor: %d MinMetaspaceExpansion: %.1fK", (double) shrink_bytes / (double) K, current_shrink_factor, _shrink_factor, (double) MinMetaspaceExpansion / (double) K); } } // Don't shrink unless it's significant if (shrink_bytes >= MinMetaspaceExpansion && ((capacity_until_GC - shrink_bytes) >= MetaspaceSize)) { size_t new_capacity_until_GC = MetaspaceGC::dec_capacity_until_GC(shrink_bytes); Metaspace::tracer()->report_gc_threshold(capacity_until_GC, new_capacity_until_GC, MetaspaceGCThresholdUpdater::ComputeNewSize); } } ////// Metaspace methods ///// const MetaspaceTracer* Metaspace::_tracer = nullptr; const void* Metaspace::_class_space_start = nullptr; const void* Metaspace::_class_space_end = nullptr; bool Metaspace::initialized() { return metaspace::MetaspaceContext::context_nonclass() != nullptr LP64_ONLY(&& (using_class_space() ? Metaspace::class_space_is_initialized() : true)); } #ifdef _LP64 void Metaspace::print_compressed_class_space(outputStream* st) { if (VirtualSpaceList::vslist_class() != nullptr) { MetaWord* base = VirtualSpaceList::vslist_class()->base_of_first_node(); size_t size = VirtualSpaceList::vslist_class()->word_size_of_first_node(); MetaWord* top = base + size; st->print("Compressed class space mapped at: " PTR_FORMAT "-" PTR_FORMAT ", reserved size: %zu", p2i(base), p2i(top), (top - base) * BytesPerWord); st->cr(); } } // Given a prereserved space, use that to set up the compressed class space list. void Metaspace::initialize_class_space(ReservedSpace rs) { assert(rs.size() >= CompressedClassSpaceSize, "%zu != %zu", rs.size(), CompressedClassSpaceSize); assert(using_class_space(), "Must be using class space"); assert(rs.size() == CompressedClassSpaceSize, "%zu != %zu", rs.size(), CompressedClassSpaceSize); assert(is_aligned(rs.base(), Metaspace::reserve_alignment()) && is_aligned(rs.size(), Metaspace::reserve_alignment()), "wrong alignment"); MetaspaceContext::initialize_class_space_context(rs); _class_space_start = rs.base(); _class_space_end = rs.end(); } // Returns true if class space has been setup (initialize_class_space). bool Metaspace::class_space_is_initialized() { return MetaspaceContext::context_class() != nullptr; } // Reserve a range of memory that is to contain narrow Klass IDs. If "try_in_low_address_ranges" // is true, we will attempt to reserve memory suitable for zero-based encoding. ReservedSpace Metaspace::reserve_address_space_for_compressed_classes(size_t size, bool optimize_for_zero_base) { char* result = nullptr; NOT_ZERO(result = (char*) CompressedKlassPointers::reserve_address_space_for_compressed_classes(size, RandomizeClassSpaceLocation, optimize_for_zero_base)); if (result == nullptr) { // Fallback: reserve anywhere log_debug(metaspace, map)("Trying anywhere..."); result = os::reserve_memory_aligned(size, Metaspace::reserve_alignment(), mtClass); } // Wrap resulting range in ReservedSpace if (result != nullptr) { log_debug(metaspace, map)("Mapped at " PTR_FORMAT, p2i(result)); assert(is_aligned(result, Metaspace::reserve_alignment()), "Alignment too small for metaspace"); return ReservedSpace(result, size, Metaspace::reserve_alignment(), os::vm_page_size(), !ExecMem, false /* special */); } else { log_debug(metaspace, map)("Failed to map."); return {}; } } #endif // _LP64 size_t Metaspace::reserve_alignment_words() { return metaspace::Settings::virtual_space_node_reserve_alignment_words(); } size_t Metaspace::commit_alignment_words() { return metaspace::Settings::commit_granule_words(); } void Metaspace::ergo_initialize() { // Must happen before using any setting from Settings::--- metaspace::Settings::ergo_initialize(); // MaxMetaspaceSize and CompressedClassSpaceSize: // // MaxMetaspaceSize is the maximum size, in bytes, of memory we are allowed // to commit for the Metaspace. // It is just a number; a limit we compare against before committing. It // does not have to be aligned to anything. // It gets used as compare value before attempting to increase the metaspace // commit charge. It defaults to max_uintx (unlimited). // // CompressedClassSpaceSize is the size, in bytes, of the address range we // pre-reserve for the compressed class space (if we use class space). // This size has to be aligned to the metaspace reserve alignment (to the // size of a root chunk). It gets aligned up from whatever value the caller // gave us to the next multiple of root chunk size. // // Note: Strictly speaking MaxMetaspaceSize and CompressedClassSpaceSize have // very little to do with each other. The notion often encountered: // MaxMetaspaceSize = CompressedClassSpaceSize + // is subtly wrong: MaxMetaspaceSize can besmaller than CompressedClassSpaceSize, // in which case we just would not be able to fully commit the class space range. // // We still adjust CompressedClassSpaceSize to reasonable limits, mainly to // save on reserved space, and to make ergnonomics less confusing. MaxMetaspaceSize = MAX2(MaxMetaspaceSize, commit_alignment()); if (UseCompressedClassPointers) { // Let Class Space not be larger than 80% of MaxMetaspaceSize. Note that is // grossly over-dimensioned for most usage scenarios; typical ratio of // class space : non class space usage is about 1:6. With many small classes, // it can get as low as 1:2. It is not a big deal though since ccs is only // reserved and will be committed on demand only. const size_t max_ccs_size = 8 * (MaxMetaspaceSize / 10); // Sanity check. const size_t max_klass_range = CompressedKlassPointers::max_klass_range_size(); assert(max_klass_range >= reserve_alignment(), "Klass range (%zu) must cover at least a full root chunk (%zu)", max_klass_range, reserve_alignment()); size_t adjusted_ccs_size = MIN3(CompressedClassSpaceSize, max_ccs_size, max_klass_range); // CCS must be aligned to root chunk size, and be at least the size of one // root chunk. adjusted_ccs_size = align_up(adjusted_ccs_size, reserve_alignment()); adjusted_ccs_size = MAX2(adjusted_ccs_size, reserve_alignment()); // Print a warning if the adjusted size differs from the users input if (CompressedClassSpaceSize != adjusted_ccs_size) { #define X "CompressedClassSpaceSize adjusted from user input " \ "%zu bytes to %zu bytes", CompressedClassSpaceSize, adjusted_ccs_size if (FLAG_IS_CMDLINE(CompressedClassSpaceSize)) { log_warning(metaspace)(X); } else { log_info(metaspace)(X); } #undef X } // Note: re-adjusting may have us left with a CompressedClassSpaceSize // larger than MaxMetaspaceSize for very small values of MaxMetaspaceSize. // Lets just live with that, its not a big deal. if (adjusted_ccs_size != CompressedClassSpaceSize) { FLAG_SET_ERGO(CompressedClassSpaceSize, adjusted_ccs_size); log_info(metaspace)("Setting CompressedClassSpaceSize to %zu.", CompressedClassSpaceSize); } } // Set MetaspaceSize, MinMetaspaceExpansion and MaxMetaspaceExpansion if (MetaspaceSize > MaxMetaspaceSize) { MetaspaceSize = MaxMetaspaceSize; } MetaspaceSize = align_down_bounded(MetaspaceSize, commit_alignment()); assert(MetaspaceSize <= MaxMetaspaceSize, "MetaspaceSize should be limited by MaxMetaspaceSize"); MinMetaspaceExpansion = align_down_bounded(MinMetaspaceExpansion, commit_alignment()); MaxMetaspaceExpansion = align_down_bounded(MaxMetaspaceExpansion, commit_alignment()); } void Metaspace::global_initialize() { MetaspaceGC::initialize(); // <- since we do not prealloc init chunks anymore is this still needed? metaspace::ChunkHeaderPool::initialize(); if (CDSConfig::is_dumping_static_archive()) { MetaspaceShared::initialize_for_static_dump(); } // If UseCompressedClassPointers=1, we have two cases: // a) if CDS is active (runtime, Xshare=on), it will create the class space // for us, initialize it and set up CompressedKlassPointers encoding. // Class space will be reserved above the mapped archives. // b) if CDS either deactivated (Xshare=off) or a static dump is to be done (Xshare:dump), // we will create the class space on our own. It will be placed above the java heap, // since we assume it has been placed in low // address regions. We may rethink this (see JDK-8244943). Failing that, // it will be placed anywhere. #if INCLUDE_CDS // case (a) if (CDSConfig::is_using_archive()) { if (!FLAG_IS_DEFAULT(CompressedClassSpaceBaseAddress)) { log_warning(metaspace)("CDS active - ignoring CompressedClassSpaceBaseAddress."); } MetaspaceShared::initialize_runtime_shared_and_meta_spaces(); // If any of the archived space fails to map, UseSharedSpaces // is reset to false. } #endif // INCLUDE_CDS #ifdef _LP64 if (using_class_space() && !class_space_is_initialized()) { assert(!CDSConfig::is_using_archive(), "CDS archive is not mapped at this point"); // case (b) (No CDS) ReservedSpace rs; const size_t size = align_up(CompressedClassSpaceSize, Metaspace::reserve_alignment()); // If CompressedClassSpaceBaseAddress is set, we attempt to force-map class space to // the given address. This is a debug-only feature aiding tests. Due to the ASLR lottery // this may fail, in which case the VM will exit after printing an appropriate message. // Tests using this switch should cope with that. if (CompressedClassSpaceBaseAddress != 0) { const address base = (address)CompressedClassSpaceBaseAddress; if (!is_aligned(base, Metaspace::reserve_alignment())) { vm_exit_during_initialization( err_msg("CompressedClassSpaceBaseAddress=" PTR_FORMAT " invalid " "(must be aligned to 0x%zx).", CompressedClassSpaceBaseAddress, Metaspace::reserve_alignment())); } rs = MemoryReserver::reserve((char*)base, size, Metaspace::reserve_alignment(), os::vm_page_size(), mtClass); if (rs.is_reserved()) { log_info(metaspace)("Successfully forced class space address to " PTR_FORMAT, p2i(base)); } else { LogTarget(Debug, metaspace) lt; if (lt.is_enabled()) { LogStream ls(lt); os::print_memory_mappings((char*)base, size, &ls); } vm_exit_during_initialization( err_msg("CompressedClassSpaceBaseAddress=" PTR_FORMAT " given, but reserving class space failed.", CompressedClassSpaceBaseAddress)); } } // ...failing that, reserve anywhere, but let platform do optimized placement: if (!rs.is_reserved()) { log_info(metaspace)("Reserving compressed class space anywhere"); rs = Metaspace::reserve_address_space_for_compressed_classes(size, true); } // ...failing that, give up. if (!rs.is_reserved()) { vm_exit_during_initialization( err_msg("Could not allocate compressed class space: %zu bytes", CompressedClassSpaceSize)); } // Mark class space as such MemTracker::record_virtual_memory_tag(rs, mtClass); // Initialize space Metaspace::initialize_class_space(rs); // Set up compressed class pointer encoding. // In CDS=off mode, we give the JVM some leeway to choose a favorable base/shift combination. CompressedKlassPointers::initialize((address)rs.base(), rs.size()); // After narrowKlass encoding scheme is decided: if the encoding base points to class space start, // establish a protection zone. Accidentally decoding a zero nKlass ID and then using it will result // in an immediate segmentation fault instead of a delayed error much later. if (CompressedKlassPointers::base() == (address)rs.base()) { // Let the protection zone be a whole commit granule. Otherwise, buddy allocator may later place neighboring // chunks in the same granule, see that the granule is not yet committed, and commit it, which would replace // the protection mapping and make the zone readable. // Alternatively, we could commit the chunk right now, but that is a tiny bit more fiddly, since we are not // fully set up yet at this point. const size_t protzone_size = metaspace::Settings::commit_granule_bytes(); // granule size >= page size const size_t protzone_wordsize = protzone_size / BytesPerWord; const metaspace::chunklevel_t lvl = metaspace::chunklevel::level_fitting_word_size(protzone_wordsize); metaspace::Metachunk* const chunk = MetaspaceContext::context_class()->cm()->get_chunk(lvl); const address protzone = (address) chunk->base(); assert(protzone == (address)rs.base(), "The very first chunk should be located at the class space start?"); assert(chunk->word_size() == protzone_wordsize, "Weird chunk size"); CompressedKlassPointers::establish_protection_zone(protzone, protzone_size); } else { assert(CompressedKlassPointers::base() == nullptr, "Zero-based encoding expected"); } } #endif // _LP64 // Initialize non-class virtual space list, and its chunk manager: MetaspaceContext::initialize_nonclass_space_context(); _tracer = new MetaspaceTracer(); #ifdef _LP64 if (UseCompressedClassPointers) { // Note: "cds" would be a better fit but keep this for backward compatibility. LogTarget(Info, gc, metaspace) lt; if (lt.is_enabled()) { LogStream ls(lt); CDS_ONLY(MetaspaceShared::print_on(&ls);) Metaspace::print_compressed_class_space(&ls); CompressedKlassPointers::print_mode(&ls); } } #endif } void Metaspace::post_initialize() { MetaspaceGC::post_initialize(); } size_t Metaspace::max_allocation_word_size() { return metaspace::chunklevel::MAX_CHUNK_WORD_SIZE; } // This version of Metaspace::allocate does not throw OOM but simply returns null, and // is suitable for calling from non-Java threads. // Callers are responsible for checking null. MetaWord* Metaspace::allocate(ClassLoaderData* loader_data, size_t word_size, MetaspaceObj::Type type, bool use_class_space) { assert(word_size <= Metaspace::max_allocation_word_size(), "allocation size too large (%zu)", word_size); assert(loader_data != nullptr, "Should never pass around a null loader_data. " "ClassLoaderData::the_null_class_loader_data() should have been used."); // Deal with concurrent unloading failed allocation starvation MetaspaceCriticalAllocation::block_if_concurrent_purge(); MetadataType mdtype = use_class_space ? ClassType : NonClassType; // Try to allocate metadata. MetaWord* result = loader_data->metaspace_non_null()->allocate(word_size, mdtype); if (result != nullptr) { #ifdef ASSERT if (using_class_space() && mdtype == ClassType) { assert(is_in_class_space(result) && is_aligned(result, CompressedKlassPointers::klass_alignment_in_bytes()), "Sanity"); } else { assert((is_in_class_space(result) || is_in_nonclass_metaspace(result)) && is_aligned(result, Metaspace::min_allocation_alignment_bytes), "Sanity"); } #endif // Zero initialize. Copy::fill_to_words((HeapWord*)result, word_size, 0); log_trace(metaspace)("Metaspace::allocate: type %d return " PTR_FORMAT ".", (int)type, p2i(result)); } return result; } MetaWord* Metaspace::allocate(ClassLoaderData* loader_data, size_t word_size, MetaspaceObj::Type type, bool use_class_space, TRAPS) { if (HAS_PENDING_EXCEPTION) { assert(false, "Should not allocate with exception pending"); return nullptr; // caller does a CHECK_NULL too } assert(!THREAD->owns_locks(), "allocating metaspace while holding mutex"); MetaWord* result = allocate(loader_data, word_size, type, use_class_space); if (result == nullptr) { MetadataType mdtype = use_class_space ? ClassType : NonClassType; tracer()->report_metaspace_allocation_failure(loader_data, word_size, type, mdtype); // Allocation failed. if (is_init_completed()) { // Only start a GC if the bootstrapping has completed. // Try to clean out some heap memory and retry. This can prevent premature // expansion of the metaspace. result = Universe::heap()->satisfy_failed_metadata_allocation(loader_data, word_size, mdtype); } if (result == nullptr) { report_metadata_oome(loader_data, word_size, type, mdtype, THREAD); assert(HAS_PENDING_EXCEPTION, "sanity"); return nullptr; } // Zero initialize. Copy::fill_to_words((HeapWord*)result, word_size, 0); log_trace(metaspace)("Metaspace::allocate: type %d return " PTR_FORMAT ".", (int)type, p2i(result)); } return result; } void Metaspace::report_metadata_oome(ClassLoaderData* loader_data, size_t word_size, MetaspaceObj::Type type, MetadataType mdtype, TRAPS) { tracer()->report_metadata_oom(loader_data, word_size, type, mdtype); // If result is still null, we are out of memory. { LogMessage(gc, metaspace, freelist, oom) log; if (log.is_info()) { log.info("Metaspace (%s) allocation failed for size %zu", is_class_space_allocation(mdtype) ? "class" : "data", word_size); ResourceMark rm; if (log.is_debug()) { if (loader_data->metaspace_or_null() != nullptr) { NonInterleavingLogStream ls(LogLevelType::Debug, log); loader_data->print_value_on(&ls); } } NonInterleavingLogStream ls(LogLevelType::Info, log); // In case of an OOM, log out a short but still useful report. MetaspaceUtils::print_basic_report(&ls, 0); } } bool out_of_compressed_class_space = false; if (is_class_space_allocation(mdtype)) { ClassLoaderMetaspace* metaspace = loader_data->metaspace_non_null(); out_of_compressed_class_space = MetaspaceUtils::committed_bytes(Metaspace::ClassType) + align_up(word_size * BytesPerWord, 4 * M) > CompressedClassSpaceSize; } // -XX:+HeapDumpOnOutOfMemoryError and -XX:OnOutOfMemoryError support const char* space_string = out_of_compressed_class_space ? "Compressed class space" : "Metaspace"; report_java_out_of_memory(space_string); if (JvmtiExport::should_post_resource_exhausted()) { JvmtiExport::post_resource_exhausted( JVMTI_RESOURCE_EXHAUSTED_OOM_ERROR, space_string); } if (!is_init_completed()) { vm_exit_during_initialization("OutOfMemoryError", space_string); } if (out_of_compressed_class_space) { THROW_OOP(Universe::out_of_memory_error_class_metaspace()); } else { THROW_OOP(Universe::out_of_memory_error_metaspace()); } } const char* Metaspace::metadata_type_name(Metaspace::MetadataType mdtype) { switch (mdtype) { case Metaspace::ClassType: return "Class"; case Metaspace::NonClassType: return "Metadata"; default: assert(false, "Got bad mdtype: %d", (int) mdtype); return nullptr; } } void Metaspace::purge(bool classes_unloaded) { // The MetaspaceCritical_lock is used by a concurrent GC to block out concurrent metaspace // allocations, that would starve critical metaspace allocations, that are about to throw // OOM if they fail; they need precedence for correctness. MutexLocker ml(MetaspaceCritical_lock, Mutex::_no_safepoint_check_flag); if (classes_unloaded) { ChunkManager* cm = ChunkManager::chunkmanager_nonclass(); if (cm != nullptr) { cm->purge(); } if (using_class_space()) { cm = ChunkManager::chunkmanager_class(); if (cm != nullptr) { cm->purge(); } } } // Try to satisfy queued metaspace allocation requests. // // It might seem unnecessary to try to process allocation requests if no // classes have been unloaded. However, this call is required for the code // in MetaspaceCriticalAllocation::try_allocate_critical to work. MetaspaceCriticalAllocation::process(); } // Returns true if pointer points into one of the metaspace regions, or // into the class space. bool Metaspace::is_in_shared_metaspace(const void* ptr) { return MetaspaceShared::is_in_shared_metaspace(ptr); } // Returns true if pointer points into one of the non-class-space metaspace regions. bool Metaspace::is_in_nonclass_metaspace(const void* ptr) { return VirtualSpaceList::vslist_nonclass()->contains((MetaWord*)ptr); }