rev 8065 : 8065331

   1 /*
   2  * Copyright (c) 2005, 2015, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  *
  23  */
  24 
  25 #include "precompiled.hpp"
  26 #include "classfile/classLoader.hpp"
  27 #include "classfile/javaClasses.hpp"
  28 #include "gc_implementation/shared/vmGCOperations.hpp"
  29 #include "memory/gcLocker.inline.hpp"
  30 #include "memory/genCollectedHeap.hpp"
  31 #include "memory/oopFactory.hpp"
  32 #include "oops/instanceKlass.hpp"
  33 #include "oops/instanceRefKlass.hpp"
  34 #include "runtime/handles.inline.hpp"
  35 #include "runtime/init.hpp"
  36 #include "runtime/interfaceSupport.hpp"
  37 #include "utilities/dtrace.hpp"
  38 #include "utilities/preserveException.hpp"
  39 #include "utilities/macros.hpp"
  40 #if INCLUDE_ALL_GCS
  41 #include "gc_implementation/g1/g1CollectedHeap.inline.hpp"
  42 #endif // INCLUDE_ALL_GCS
  43 
  44 VM_GC_Operation::~VM_GC_Operation() {
  45   CollectedHeap* ch = Universe::heap();
  46   ch->collector_policy()->set_all_soft_refs_clear(false);
  47 }
  48 
  49 // The same dtrace probe can't be inserted in two different files, so we
  50 // have to call it here, so it's only in one file.  Can't create new probes
  51 // for the other file anymore.   The dtrace probes have to remain stable.
  52 void VM_GC_Operation::notify_gc_begin(bool full) {
  53   HOTSPOT_GC_BEGIN(
  54                    full);
  55   HS_DTRACE_WORKAROUND_TAIL_CALL_BUG();
  56 }
  57 
  58 void VM_GC_Operation::notify_gc_end() {
  59   HOTSPOT_GC_END();
  60   HS_DTRACE_WORKAROUND_TAIL_CALL_BUG();
  61 }
  62 
  63 void VM_GC_Operation::acquire_pending_list_lock() {
  64   // we may enter this with pending exception set
  65   InstanceRefKlass::acquire_pending_list_lock(&_pending_list_basic_lock);
  66 }
  67 
  68 
  69 void VM_GC_Operation::release_and_notify_pending_list_lock() {
  70 
  71   InstanceRefKlass::release_and_notify_pending_list_lock(&_pending_list_basic_lock);
  72 }
  73 
  74 // Allocations may fail in several threads at about the same time,
  75 // resulting in multiple gc requests.  We only want to do one of them.
  76 // In case a GC locker is active and the need for a GC is already signaled,
  77 // we want to skip this GC attempt altogether, without doing a futile
  78 // safepoint operation.
  79 bool VM_GC_Operation::skip_operation() const {
  80   bool skip = (_gc_count_before != Universe::heap()->total_collections());
  81   if (_full && skip) {
  82     skip = (_full_gc_count_before != Universe::heap()->total_full_collections());
  83   }
  84   if (!skip && GC_locker::is_active_and_needs_gc()) {
  85     skip = Universe::heap()->is_maximal_no_gc();
  86     assert(!(skip && (_gc_cause == GCCause::_gc_locker)),
  87            "GC_locker cannot be active when initiating GC");
  88   }
  89   return skip;
  90 }
  91 
  92 bool VM_GC_Operation::doit_prologue() {
  93   assert(Thread::current()->is_Java_thread(), "just checking");
  94   assert(((_gc_cause != GCCause::_no_gc) &&
  95           (_gc_cause != GCCause::_no_cause_specified)), "Illegal GCCause");
  96 
  97   // To be able to handle a GC the VM initialization needs to be completed.
  98   if (!is_init_completed()) {
  99     vm_exit_during_initialization(
 100       err_msg("GC triggered before VM initialization completed. Try increasing "
 101               "NewSize, current value " SIZE_FORMAT "%s.",
 102               byte_size_in_proper_unit(NewSize),
 103               proper_unit_for_byte_size(NewSize)));
 104   }
 105 
 106   acquire_pending_list_lock();
 107   // If the GC count has changed someone beat us to the collection
 108   // Get the Heap_lock after the pending_list_lock.
 109   Heap_lock->lock();
 110 
 111   // Check invocations
 112   if (skip_operation()) {
 113     // skip collection
 114     Heap_lock->unlock();
 115     release_and_notify_pending_list_lock();
 116     _prologue_succeeded = false;
 117   } else {
 118     _prologue_succeeded = true;
 119   }
 120   return _prologue_succeeded;
 121 }
 122 
 123 
 124 void VM_GC_Operation::doit_epilogue() {
 125   assert(Thread::current()->is_Java_thread(), "just checking");
 126   // Release the Heap_lock first.
 127   Heap_lock->unlock();
 128   release_and_notify_pending_list_lock();
 129 }
 130 
 131 bool VM_GC_HeapInspection::doit_prologue() {
 132   if (Universe::heap()->supports_heap_inspection()) {
 133     return VM_GC_Operation::doit_prologue();
 134   } else {
 135     return false;
 136   }
 137 }
 138 
 139 bool VM_GC_HeapInspection::skip_operation() const {
 140   assert(Universe::heap()->supports_heap_inspection(), "huh?");
 141   return false;
 142 }
 143 
 144 bool VM_GC_HeapInspection::collect() {
 145   if (GC_locker::is_active()) {
 146     return false;
 147   }
 148   Universe::heap()->collect_as_vm_thread(GCCause::_heap_inspection);
 149   return true;
 150 }
 151 
 152 void VM_GC_HeapInspection::doit() {
 153   HandleMark hm;
 154   Universe::heap()->ensure_parsability(false); // must happen, even if collection does
 155                                                // not happen (e.g. due to GC_locker)
 156                                                // or _full_gc being false
 157   if (_full_gc) {
 158     if (!collect()) {
 159       // The collection attempt was skipped because the gc locker is held.
 160       // The following dump may then be a tad misleading to someone expecting
 161       // only live objects to show up in the dump (see CR 6944195). Just issue
 162       // a suitable warning in that case and do not attempt to do a collection.
 163       // The latter is a subtle point, because even a failed attempt
 164       // to GC will, in fact, induce one in the future, which we
 165       // probably want to avoid in this case because the GC that we may
 166       // be about to attempt holds value for us only
 167       // if it happens now and not if it happens in the eventual
 168       // future.
 169       warning("GC locker is held; pre-dump GC was skipped");
 170     }
 171   }
 172   HeapInspection inspect(_csv_format, _print_help, _print_class_stats,
 173                          _columns);
 174   inspect.heap_inspection(_out);
 175 }
 176 
 177 
 178 void VM_GenCollectForAllocation::doit() {
 179   SvcGCMarker sgcm(SvcGCMarker::MINOR);
 180 
 181   GenCollectedHeap* gch = GenCollectedHeap::heap();
 182   GCCauseSetter gccs(gch, _gc_cause);
 183   _result = gch->satisfy_failed_allocation(_word_size, _tlab);
 184   assert(gch->is_in_reserved_or_null(_result), "result not in heap");
 185 
 186   if (_result == NULL && GC_locker::is_active_and_needs_gc()) {
 187     set_gc_locked();
 188   }
 189 }
 190 
 191 void VM_GenCollectFull::doit() {
 192   SvcGCMarker sgcm(SvcGCMarker::FULL);
 193 
 194   GenCollectedHeap* gch = GenCollectedHeap::heap();
 195   GCCauseSetter gccs(gch, _gc_cause);
 196   gch->do_full_collection(gch->must_clear_all_soft_refs(), _max_level);
 197 }
 198 
 199 VM_CollectForMetadataAllocation::VM_CollectForMetadataAllocation(ClassLoaderData* loader_data,
 200                                                                  size_t size,
 201                                                                  Metaspace::MetadataType mdtype,
 202                                                                  uint gc_count_before,
 203                                                                  uint full_gc_count_before,
 204                                                                  GCCause::Cause gc_cause)
 205     : VM_GC_Operation(gc_count_before, gc_cause, full_gc_count_before, true),
 206       _loader_data(loader_data), _size(size), _mdtype(mdtype), _result(NULL) {
 207   assert(_size != 0, "An allocation should always be requested with this operation.");
 208   AllocTracer::send_allocation_requiring_gc_event(_size * HeapWordSize, GCId::peek());
 209 }
 210 
 211 // Returns true iff concurrent GCs unloads metadata.
 212 bool VM_CollectForMetadataAllocation::initiate_concurrent_GC() {
 213 #if INCLUDE_ALL_GCS
 214   if (UseConcMarkSweepGC && CMSClassUnloadingEnabled) {
 215     MetaspaceGC::set_should_concurrent_collect(true);
 216     return true;
 217   }
 218 
 219   if (UseG1GC && ClassUnloadingWithConcurrentMark) {
 220     G1CollectedHeap* g1h = G1CollectedHeap::heap();
 221     g1h->g1_policy()->set_initiate_conc_mark_if_possible();
 222 
 223     GCCauseSetter x(g1h, _gc_cause);
 224 
 225     // At this point we are supposed to start a concurrent cycle. We
 226     // will do so if one is not already in progress.
 227     bool should_start = g1h->g1_policy()->force_initial_mark_if_outside_cycle(_gc_cause);
 228 
 229     if (should_start) {
 230       double pause_target = g1h->g1_policy()->max_pause_time_ms();
 231       g1h->do_collection_pause_at_safepoint(pause_target);
 232     }
 233     return true;
 234   }
 235 #endif
 236 
 237   return false;
 238 }
 239 
 240 static void log_metaspace_alloc_failure_for_concurrent_GC() {
 241   if (Verbose && PrintGCDetails) {
 242     if (UseConcMarkSweepGC) {
 243       gclog_or_tty->print_cr("\nCMS full GC for Metaspace");
 244     } else if (UseG1GC) {
 245       gclog_or_tty->print_cr("\nG1 full GC for Metaspace");
 246     }
 247   }
 248 }
 249 
 250 void VM_CollectForMetadataAllocation::doit() {
 251   SvcGCMarker sgcm(SvcGCMarker::FULL);
 252 
 253   CollectedHeap* heap = Universe::heap();
 254   GCCauseSetter gccs(heap, _gc_cause);
 255 
 256   // Check again if the space is available.  Another thread
 257   // may have similarly failed a metadata allocation and induced
 258   // a GC that freed space for the allocation.
 259   if (!MetadataAllocationFailALot) {
 260     _result = _loader_data->metaspace_non_null()->allocate(_size, _mdtype);
 261     if (_result != NULL) {
 262       return;
 263     }
 264   }
 265 
 266   if (initiate_concurrent_GC()) {
 267     // For CMS and G1 expand since the collection is going to be concurrent.
 268     _result = _loader_data->metaspace_non_null()->expand_and_allocate(_size, _mdtype);
 269     if (_result != NULL) {
 270       return;
 271     }
 272 
 273     log_metaspace_alloc_failure_for_concurrent_GC();
 274   }
 275 
 276   // Don't clear the soft refs yet.
 277   heap->collect_as_vm_thread(GCCause::_metadata_GC_threshold);
 278   // After a GC try to allocate without expanding.  Could fail
 279   // and expansion will be tried below.
 280   _result = _loader_data->metaspace_non_null()->allocate(_size, _mdtype);
 281   if (_result != NULL) {
 282     return;
 283   }
 284 
 285   // If still failing, allow the Metaspace to expand.
 286   // See delta_capacity_until_GC() for explanation of the
 287   // amount of the expansion.
 288   // This should work unless there really is no more space
 289   // or a MaxMetaspaceSize has been specified on the command line.
 290   _result = _loader_data->metaspace_non_null()->expand_and_allocate(_size, _mdtype);
 291   if (_result != NULL) {
 292     return;
 293   }
 294 
 295   // If expansion failed, do a last-ditch collection and try allocating
 296   // again.  A last-ditch collection will clear softrefs.  This
 297   // behavior is similar to the last-ditch collection done for perm
 298   // gen when it was full and a collection for failed allocation
 299   // did not free perm gen space.
 300   heap->collect_as_vm_thread(GCCause::_last_ditch_collection);
 301   _result = _loader_data->metaspace_non_null()->allocate(_size, _mdtype);
 302   if (_result != NULL) {
 303     return;
 304   }
 305 
 306   if (Verbose && PrintGCDetails) {
 307     gclog_or_tty->print_cr("\nAfter Metaspace GC failed to allocate size "
 308                            SIZE_FORMAT, _size);
 309   }
 310 
 311   if (GC_locker::is_active_and_needs_gc()) {
 312     set_gc_locked();
 313   }
 314 }
 315 
 316 VM_CollectForAllocation::VM_CollectForAllocation(size_t word_size, uint gc_count_before, GCCause::Cause cause)
 317     : VM_GC_Operation(gc_count_before, cause), _result(NULL), _word_size(word_size) {
 318   // Only report if operation was really caused by an allocation.
 319   if (_word_size != 0) {
 320     AllocTracer::send_allocation_requiring_gc_event(_word_size * HeapWordSize, GCId::peek());
 321   }
 322 }
--- EOF ---