openjdk17 jvm堆空间分配

##堆空间分配源码

jint Universe::initialize_heap() {assert(_collectedHeap == NULL, "Heap already created");_collectedHeap = GCConfig::arguments()->create_heap();log_info(gc)("Using %s", _collectedHeap->name());return _collectedHeap->initialize();
}

##

jint G1CollectedHeap::initialize() {// Necessary to satisfy locking discipline assertions.MutexLocker x(Heap_lock);// While there are no constraints in the GC code that HeapWordSize// be any particular value, there are multiple other areas in the// system which believe this to be true (e.g. oop->object_size in some// cases incorrectly returns the size in wordSize units rather than// HeapWordSize).guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");size_t init_byte_size = InitialHeapSize;size_t reserved_byte_size = G1Arguments::heap_reserved_size_bytes();// Ensure that the sizes are properly aligned.Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");Universe::check_alignment(reserved_byte_size, HeapRegion::GrainBytes, "g1 heap");Universe::check_alignment(reserved_byte_size, HeapAlignment, "g1 heap");// Reserve the maximum.// When compressed oops are enabled, the preferred heap base// is calculated by subtracting the requested size from the// 32Gb boundary and using the result as the base address for// heap reservation. If the requested size is not aligned to// HeapRegion::GrainBytes (i.e. the alignment that is passed// into the ReservedHeapSpace constructor) then the actual// base of the reserved heap may end up differing from the// address that was requested (i.e. the preferred heap base).// If this happens then we could end up using a non-optimal// compressed oops mode.ReservedHeapSpace heap_rs = Universe::reserve_heap(reserved_byte_size,HeapAlignment);initialize_reserved_region(heap_rs);// Create the barrier set for the entire reserved region.G1CardTable* ct = new G1CardTable(heap_rs.region());ct->initialize();G1BarrierSet* bs = new G1BarrierSet(ct);bs->initialize();assert(bs->is_a(BarrierSet::G1BarrierSet), "sanity");BarrierSet::set_barrier_set(bs);_card_table = ct;{G1SATBMarkQueueSet& satbqs = bs->satb_mark_queue_set();satbqs.set_process_completed_buffers_threshold(G1SATBProcessCompletedThreshold);satbqs.set_buffer_enqueue_threshold_percentage(G1SATBBufferEnqueueingThresholdPercent);}// Create the hot card cache._hot_card_cache = new G1HotCardCache(this);// Create space mappers.size_t page_size = heap_rs.page_size();G1RegionToSpaceMapper* heap_storage =G1RegionToSpaceMapper::create_mapper(heap_rs,heap_rs.size(),page_size,HeapRegion::GrainBytes,1,mtJavaHeap);if(heap_storage == NULL) {vm_shutdown_during_initialization("Could not initialize G1 heap");return JNI_ERR;}os::trace_page_sizes("Heap",MinHeapSize,reserved_byte_size,page_size,heap_rs.base(),heap_rs.size());heap_storage->set_mapping_changed_listener(&_listener);// Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps.G1RegionToSpaceMapper* bot_storage =create_aux_memory_mapper("Block Offset Table",G1BlockOffsetTable::compute_size(heap_rs.size() / HeapWordSize),G1BlockOffsetTable::heap_map_factor());G1RegionToSpaceMapper* cardtable_storage =create_aux_memory_mapper("Card Table",G1CardTable::compute_size(heap_rs.size() / HeapWordSize),G1CardTable::heap_map_factor());G1RegionToSpaceMapper* card_counts_storage =create_aux_memory_mapper("Card Counts Table",G1CardCounts::compute_size(heap_rs.size() / HeapWordSize),G1CardCounts::heap_map_factor());size_t bitmap_size = G1CMBitMap::compute_size(heap_rs.size());G1RegionToSpaceMapper* prev_bitmap_storage =create_aux_memory_mapper("Prev Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());G1RegionToSpaceMapper* next_bitmap_storage =create_aux_memory_mapper("Next Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());_hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);_card_table->initialize(cardtable_storage);// Do later initialization work for concurrent refinement._hot_card_cache->initialize(card_counts_storage);// 6843694 - ensure that the maximum region index can fit// in the remembered set structures.const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;guarantee((max_reserved_regions() - 1) <= max_region_idx, "too many regions");// The G1FromCardCache reserves card with value 0 as "invalid", so the heap must not// start within the first card.guarantee(heap_rs.base() >= (char*)G1CardTable::card_size, "Java heap must not start within the first card.");G1FromCardCache::initialize(max_reserved_regions());// Also create a G1 rem set._rem_set = new G1RemSet(this, _card_table, _hot_card_cache);_rem_set->initialize(max_reserved_regions());size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,"too many cards per region");FreeRegionList::set_unrealistically_long_length(max_regions() + 1);_bot = new G1BlockOffsetTable(reserved(), bot_storage);{size_t granularity = HeapRegion::GrainBytes;_region_attr.initialize(reserved(), granularity);_humongous_reclaim_candidates.initialize(reserved(), granularity);}_workers = new WorkGang("GC Thread", ParallelGCThreads,true /* are_GC_task_threads */,false /* are_ConcurrentGC_threads */);if (_workers == NULL) {return JNI_ENOMEM;}_workers->initialize_workers();_numa->set_region_info(HeapRegion::GrainBytes, page_size);// Create the G1ConcurrentMark data structure and thread.// (Must do this late, so that "max_[reserved_]regions" is defined.)_cm = new G1ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);_cm_thread = _cm->cm_thread();// Now expand into the initial heap size.if (!expand(init_byte_size, _workers)) {vm_shutdown_during_initialization("Failed to allocate initial heap.");return JNI_ENOMEM;}// Perform any initialization actions delegated to the policy.policy()->init(this, &_collection_set);jint ecode = initialize_concurrent_refinement();if (ecode != JNI_OK) {return ecode;}ecode = initialize_service_thread();if (ecode != JNI_OK) {return ecode;}// Initialize and schedule sampling task on service thread._rem_set->initialize_sampling_task(service_thread());// Create and schedule the periodic gc task on the service thread._periodic_gc_task = new G1PeriodicGCTask("Periodic GC Task");_service_thread->register_task(_periodic_gc_task);{G1DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set();dcqs.set_process_cards_threshold(concurrent_refine()->yellow_zone());dcqs.set_max_cards(concurrent_refine()->red_zone());}// Here we allocate the dummy HeapRegion that is required by the// G1AllocRegion class.HeapRegion* dummy_region = _hrm.get_dummy_region();// We'll re-use the same region whether the alloc region will// require BOT updates or not and, if it doesn't, then a non-young// region will complain that it cannot support allocations without// BOT updates. So we'll tag the dummy region as eden to avoid that.dummy_region->set_eden();// Make sure it's full.dummy_region->set_top(dummy_region->end());G1AllocRegion::setup(this, dummy_region);_allocator->init_mutator_alloc_regions();// Do create of the monitoring and management support so that// values in the heap have been properly initialized._g1mm = new G1MonitoringSupport(this);_preserved_marks_set.init(ParallelGCThreads);_collection_set.initialize(max_reserved_regions());_regions_failed_evacuation = NEW_C_HEAP_ARRAY(volatile bool, max_regions(), mtGC);G1InitLogger::print();return JNI_OK;
}

##

ReservedHeapSpace Universe::reserve_heap(size_t heap_size, size_t alignment) {assert(alignment <= Arguments::conservative_max_heap_alignment(),"actual alignment " SIZE_FORMAT " must be within maximum heap alignment " SIZE_FORMAT,alignment, Arguments::conservative_max_heap_alignment());size_t total_reserved = align_up(heap_size, alignment);assert(!UseCompressedOops || (total_reserved <= (OopEncodingHeapMax - os::vm_page_size())),"heap size is too big for compressed oops");size_t page_size = os::vm_page_size();if (UseLargePages && is_aligned(alignment, os::large_page_size())) {page_size = os::large_page_size();} else {// Parallel is the only collector that might opt out of using large pages// for the heap.assert(!UseLargePages || UseParallelGC , "Wrong alignment to use large pages");}// Now create the space.ReservedHeapSpace total_rs(total_reserved, alignment, page_size, AllocateHeapAt);if (total_rs.is_reserved()) {assert((total_reserved == total_rs.size()) && ((uintptr_t)total_rs.base() % alignment == 0),"must be exactly of required size and alignment");// We are good.if (AllocateHeapAt != NULL) {log_info(gc,heap)("Successfully allocated Java heap at location %s", AllocateHeapAt);}if (UseCompressedOops) {CompressedOops::initialize(total_rs);}Universe::calculate_verify_data((HeapWord*)total_rs.base(), (HeapWord*)total_rs.end());return total_rs;}vm_exit_during_initialization(err_msg("Could not reserve enough space for " SIZE_FORMAT "KB object heap",total_reserved/K));// satisfy compilerShouldNotReachHere();return ReservedHeapSpace(0, 0, os::vm_page_size());
}

##

bool G1CollectedHeap::expand(size_t expand_bytes, WorkGang* pretouch_workers, double* expand_time_ms) {size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);aligned_expand_bytes = align_up(aligned_expand_bytes,HeapRegion::GrainBytes);log_debug(gc, ergo, heap)("Expand the heap. requested expansion amount: " SIZE_FORMAT "B expansion amount: " SIZE_FORMAT "B",expand_bytes, aligned_expand_bytes);if (is_maximal_no_gc()) {log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)");return false;}double expand_heap_start_time_sec = os::elapsedTime();uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);assert(regions_to_expand > 0, "Must expand by at least one region");uint expanded_by = _hrm.expand_by(regions_to_expand, pretouch_workers);if (expand_time_ms != NULL) {*expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS;}if (expanded_by > 0) {size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");policy()->record_new_heap_size(num_regions());} else {log_debug(gc, ergo, heap)("Did not expand the heap (heap expansion operation failed)");// The expansion of the virtual storage space was unsuccessful.// Let's see if it was because we ran out of swap.if (G1ExitOnExpansionFailure &&_hrm.available() >= regions_to_expand) {// We had head room...vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");}}return regions_to_expand > 0;
}

##gdb调试openjdk17 堆内存分配

#0  anon_mmap (requested_addr=0xfce00000 <error: Cannot access memory at address 0xfce00000>, bytes=52428800)at /home/yym/openjdk17/jdk17-master/src/hotspot/os/linux/os_linux.cpp:3389
#1  0x00007ffff687cc9c in os::pd_attempt_reserve_memory_at (requested_addr=0xfce00000 <error: Cannot access memory at address 0xfce00000>, bytes=52428800, exec=false)at /home/yym/openjdk17/jdk17-master/src/hotspot/os/linux/os_linux.cpp:4182
#2  0x00007ffff6870247 in os::attempt_reserve_memory_at (addr=0xfce00000 <error: Cannot access memory at address 0xfce00000>, bytes=52428800, executable=false)at /home/yym/openjdk17/jdk17-master/src/hotspot/share/runtime/os.cpp:1749
#3  0x00007ffff6bf2df5 in attempt_map_or_reserve_memory_at (base=0xfce00000 <error: Cannot access memory at address 0xfce00000>, size=52428800, fd=-1, executable=false)at /home/yym/openjdk17/jdk17-master/src/hotspot/share/memory/virtualspace.cpp:87
#4  0x00007ffff6bf3172 in reserve_memory (requested_address=0xfce00000 <error: Cannot access memory at address 0xfce00000>, size=52428800, alignment=2097152, fd=-1, exec=false)at /home/yym/openjdk17/jdk17-master/src/hotspot/share/memory/virtualspace.cpp:152
#5  0x00007ffff6bf35a4 in ReservedSpace::reserve (this=0x7ffff7bfe730, size=52428800, alignment=2097152, page_size=4096,requested_address=0xfce00000 <error: Cannot access memory at address 0xfce00000>, executable=false)at /home/yym/openjdk17/jdk17-master/src/hotspot/share/memory/virtualspace.cpp:250
#6  0x00007ffff6bf3e99 in ReservedHeapSpace::try_reserve_heap (this=0x7ffff7bfe730, size=52428800, alignment=2097152, page_size=4096,requested_address=0xfce00000 <error: Cannot access memory at address 0xfce00000>) at /home/yym/openjdk17/jdk17-master/src/hotspot/share/memory/virtualspace.cpp:391
#7  0x00007ffff6bf3fa5 in ReservedHeapSpace::try_reserve_range (this=0x7ffff7bfe730, highest_start=0xfce00000 <error: Cannot access memory at address 0xfce00000>,lowest_start=0x80000000 <error: Cannot access memory at address 0x80000000>, attach_point_alignment=2097152,aligned_heap_base_min_address=0x80000000 <error: Cannot access memory at address 0x80000000>, upper_bound=0x100000000 <error: Cannot access memory at address 0x100000000>,size=52428800, alignment=2097152, page_size=4096) at /home/yym/openjdk17/jdk17-master/src/hotspot/share/memory/virtualspace.cpp:423
#8  0x00007ffff6bf44a4 in ReservedHeapSpace::initialize_compressed_heap (this=0x7ffff7bfe730, size=52428800, alignment=2097152, page_size=4096)at /home/yym/openjdk17/jdk17-master/src/hotspot/share/memory/virtualspace.cpp:525
#9  0x00007ffff6bf49c1 in ReservedHeapSpace::ReservedHeapSpace (this=0x7ffff7bfe730, size=52428800, alignment=2097152, page_size=4096, heap_allocation_directory=0x0)at /home/yym/openjdk17/jdk17-master/src/hotspot/share/memory/virtualspace.cpp:610
#10 0x00007ffff6b986c1 in Universe::reserve_heap (heap_size=52428800, alignment=2097152) at /home/yym/openjdk17/jdk17-master/src/hotspot/share/memory/universe.cpp:829
#11 0x00007ffff61daeb5 in G1CollectedHeap::initialize (this=0x7ffff00453d0) at /home/yym/openjdk17/jdk17-master/src/hotspot/share/gc/g1/g1CollectedHeap.cpp:1601
#12 0x00007ffff6b98464 in Universe::initialize_heap () at /home/yym/openjdk17/jdk17-master/src/hotspot/share/memory/universe.cpp:799
#13 0x00007ffff6b981e0 in universe_init () at /home/yym/openjdk17/jdk17-master/src/hotspot/share/memory/universe.cpp:734
#14 0x00007ffff633fe8c in init_globals () at /home/yym/openjdk17/jdk17-master/src/hotspot/share/runtime/init.cpp:122
#15 0x00007ffff6b60ccb in Threads::create_vm (args=0x7ffff7bfed50, canTryAgain=0x7ffff7bfec5b) at /home/yym/openjdk17/jdk17-master/src/hotspot/share/runtime/thread.cpp:2852
#16 0x00007ffff644f659 in JNI_CreateJavaVM_inner (vm=0x7ffff7bfeda8, penv=0x7ffff7bfedb0, args=0x7ffff7bfed50)at /home/yym/openjdk17/jdk17-master/src/hotspot/share/prims/jni.cpp:3621
#17 0x00007ffff644f9a5 in JNI_CreateJavaVM (vm=0x7ffff7bfeda8, penv=0x7ffff7bfedb0, args=0x7ffff7bfed50) at /home/yym/openjdk17/jdk17-master/src/hotspot/share/prims/jni.cpp:3709
#18 0x00007ffff7facd29 in InitializeJVM (pvm=0x7ffff7bfeda8, penv=0x7ffff7bfedb0, ifn=0x7ffff7bfee00)at /home/yym/openjdk17/jdk17-master/src/java.base/share/native/libjli/java.c:1541
#19 0x00007ffff7fa9623 in JavaMain (_args=0x7fffffffaef0) at /home/yym/openjdk17/jdk17-master/src/java.base/share/native/libjli/java.c:415
#20 0x00007ffff7fb08ab in ThreadJavaMain (args=0x7fffffffaef0) at /home/yym/openjdk17/jdk17-master/src/java.base/unix/native/libjli/java_md.c:651
#21 0x00007ffff7c94ac3 in start_thread (arg=<optimized out>) at ./nptl/pthread_create.c:442
#22 0x00007ffff7d26850 in clone3 () at ../sysdeps/unix/sysv/linux/x86_64/clone3.S:81

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