1 /*
   2  * Copyright (c) 2005, 2013, 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 // The same dtrace probe can't be inserted in two different files, so we
  45 // have to call it here, so it's only in one file.  Can't create new probes
  46 // for the other file anymore.   The dtrace probes have to remain stable.
  47 void VM_GC_Operation::notify_gc_begin(bool full) {
  48   HOTSPOT_GC_BEGIN(
  49                    full);
  50   HS_DTRACE_WORKAROUND_TAIL_CALL_BUG();
  51 }
  52 
  53 void VM_GC_Operation::notify_gc_end() {
  54   HOTSPOT_GC_END();
  55   HS_DTRACE_WORKAROUND_TAIL_CALL_BUG();
  56 }
  57 
  58 void VM_GC_Operation::acquire_pending_list_lock() {
  59   // we may enter this with pending exception set
  60   InstanceRefKlass::acquire_pending_list_lock(&_pending_list_basic_lock);
  61 }
  62 
  63 
  64 void VM_GC_Operation::release_and_notify_pending_list_lock() {
  65 
  66   InstanceRefKlass::release_and_notify_pending_list_lock(&_pending_list_basic_lock);
  67 }
  68 
  69 // Allocations may fail in several threads at about the same time,
  70 // resulting in multiple gc requests.  We only want to do one of them.
  71 // In case a GC locker is active and the need for a GC is already signaled,
  72 // we want to skip this GC attempt altogether, without doing a futile
  73 // safepoint operation.
  74 bool VM_GC_Operation::skip_operation() const {
  75   bool skip = (_gc_count_before != Universe::heap()->total_collections());
  76   if (_full && skip) {
  77     skip = (_full_gc_count_before != Universe::heap()->total_full_collections());
  78   }
  79   if (!skip && GC_locker::is_active_and_needs_gc()) {
  80     skip = Universe::heap()->is_maximal_no_gc();
  81     assert(!(skip && (_gc_cause == GCCause::_gc_locker)),
  82            "GC_locker cannot be active when initiating GC");
  83   }
  84   return skip;
  85 }
  86 
  87 bool VM_GC_Operation::doit_prologue() {
  88   assert(Thread::current()->is_Java_thread(), "just checking");
  89   assert(((_gc_cause != GCCause::_no_gc) &&
  90           (_gc_cause != GCCause::_no_cause_specified)), "Illegal GCCause");
  91 
  92   // To be able to handle a GC the VM initialization needs to be completed.
  93   if (!is_init_completed()) {
  94     vm_exit_during_initialization(
  95       err_msg("GC triggered before VM initialization completed. Try increasing "
  96               "NewSize, current value " UINTX_FORMAT "%s.",
  97               byte_size_in_proper_unit(NewSize),
  98               proper_unit_for_byte_size(NewSize)));
  99   }
 100 
 101   acquire_pending_list_lock();
 102   // If the GC count has changed someone beat us to the collection
 103   // Get the Heap_lock after the pending_list_lock.
 104   Heap_lock->lock();
 105 
 106   // Check invocations
 107   if (skip_operation()) {
 108     // skip collection
 109     Heap_lock->unlock();
 110     release_and_notify_pending_list_lock();
 111     _prologue_succeeded = false;
 112   } else {
 113     _prologue_succeeded = true;
 114     SharedHeap* sh = SharedHeap::heap();
 115     if (sh != NULL) sh->_thread_holds_heap_lock_for_gc = true;
 116   }
 117   return _prologue_succeeded;
 118 }
 119 
 120 
 121 void VM_GC_Operation::doit_epilogue() {
 122   assert(Thread::current()->is_Java_thread(), "just checking");
 123   // Release the Heap_lock first.
 124   SharedHeap* sh = SharedHeap::heap();
 125   if (sh != NULL) sh->_thread_holds_heap_lock_for_gc = false;
 126   Heap_lock->unlock();
 127   release_and_notify_pending_list_lock();
 128 }
 129 
 130 bool VM_GC_HeapInspection::doit_prologue() {
 131   if (Universe::heap()->supports_heap_inspection()) {
 132     return VM_GC_Operation::doit_prologue();
 133   } else {
 134     return false;
 135   }
 136 }
 137 
 138 bool VM_GC_HeapInspection::skip_operation() const {
 139   assert(Universe::heap()->supports_heap_inspection(), "huh?");
 140   return false;
 141 }
 142 
 143 bool VM_GC_HeapInspection::collect() {
 144   if (GC_locker::is_active()) {
 145     return false;
 146   }
 147   Universe::heap()->collect_as_vm_thread(GCCause::_heap_inspection);
 148   return true;
 149 }
 150 
 151 void VM_GC_HeapInspection::doit() {
 152   HandleMark hm;
 153   Universe::heap()->ensure_parsability(false); // must happen, even if collection does
 154                                                // not happen (e.g. due to GC_locker)
 155                                                // or _full_gc being false
 156   if (_full_gc) {
 157     if (!collect()) {
 158       // The collection attempt was skipped because the gc locker is held.
 159       // The following dump may then be a tad misleading to someone expecting
 160       // only live objects to show up in the dump (see CR 6944195). Just issue
 161       // a suitable warning in that case and do not attempt to do a collection.
 162       // The latter is a subtle point, because even a failed attempt
 163       // to GC will, in fact, induce one in the future, which we
 164       // probably want to avoid in this case because the GC that we may
 165       // be about to attempt holds value for us only
 166       // if it happens now and not if it happens in the eventual
 167       // future.
 168       warning("GC locker is held; pre-dump GC was skipped");
 169     }
 170   }
 171   HeapInspection inspect(_csv_format, _print_help, _print_class_stats,
 172                          _columns);
 173   inspect.heap_inspection(_out);
 174 }
 175 
 176 
 177 void VM_GenCollectForAllocation::doit() {
 178   SvcGCMarker sgcm(SvcGCMarker::MINOR);
 179 
 180   GenCollectedHeap* gch = GenCollectedHeap::heap();
 181   GCCauseSetter gccs(gch, _gc_cause);
 182   _res = gch->satisfy_failed_allocation(_size, _tlab);
 183   assert(gch->is_in_reserved_or_null(_res), "result not in heap");
 184 
 185   if (_res == NULL && GC_locker::is_active_and_needs_gc()) {
 186     set_gc_locked();
 187   }
 188 }
 189 
 190 void VM_GenCollectFull::doit() {
 191   SvcGCMarker sgcm(SvcGCMarker::FULL);
 192 
 193   GenCollectedHeap* gch = GenCollectedHeap::heap();
 194   GCCauseSetter gccs(gch, _gc_cause);
 195   gch->do_full_collection(gch->must_clear_all_soft_refs(), _max_level);
 196 }
 197 
 198 bool VM_CollectForMetadataAllocation::initiate_concurrent_GC() {
 199 #if INCLUDE_ALL_GCS
 200   if (UseConcMarkSweepGC && CMSClassUnloadingEnabled) {
 201     MetaspaceGC::set_should_concurrent_collect(true);
 202     return true;
 203   }
 204 
 205   if (UseG1GC) {
 206     G1CollectedHeap* g1h = G1CollectedHeap::heap();
 207     g1h->g1_policy()->set_initiate_conc_mark_if_possible();
 208 
 209     GCCauseSetter x(g1h, _gc_cause);
 210 
 211     // At this point we are supposed to start a concurrent cycle. We
 212     // will do so if one is not already in progress.
 213     bool should_start = g1h->g1_policy()->force_initial_mark_if_outside_cycle(_gc_cause);
 214 
 215     if (should_start) {
 216       double pause_target = g1h->g1_policy()->max_pause_time_ms();
 217       g1h->do_collection_pause_at_safepoint(pause_target);
 218     }
 219     return true;
 220   }
 221 #endif
 222 
 223   return false;
 224 }
 225 
 226 static void log_metaspace_alloc_failure_for_concurrent_GC() {
 227   if (Verbose && PrintGCDetails) {
 228     if (UseConcMarkSweepGC) {
 229       gclog_or_tty->print_cr("\nCMS full GC for Metaspace");
 230     } else if (UseG1GC) {
 231       gclog_or_tty->print_cr("\nG1 full GC for Metaspace");
 232     }
 233   }
 234 }
 235 
 236 void VM_CollectForMetadataAllocation::doit() {
 237   SvcGCMarker sgcm(SvcGCMarker::FULL);
 238 
 239   CollectedHeap* heap = Universe::heap();
 240   GCCauseSetter gccs(heap, _gc_cause);
 241 
 242   // Check again if the space is available.  Another thread
 243   // may have similarly failed a metadata allocation and induced
 244   // a GC that freed space for the allocation.
 245   if (!MetadataAllocationFailALot) {
 246     _result = _loader_data->metaspace_non_null()->allocate(_size, _mdtype);
 247     if (_result != NULL) {
 248       return;
 249     }
 250   }
 251 
 252   if (initiate_concurrent_GC()) {
 253     // For CMS and G1 expand since the collection is going to be concurrent.
 254     _result = _loader_data->metaspace_non_null()->expand_and_allocate(_size, _mdtype);
 255     if (_result != NULL) {
 256       return;
 257     }
 258 
 259     log_metaspace_alloc_failure_for_concurrent_GC();
 260   }
 261 
 262   // Don't clear the soft refs yet.
 263   heap->collect_as_vm_thread(GCCause::_metadata_GC_threshold);
 264   // After a GC try to allocate without expanding.  Could fail
 265   // and expansion will be tried below.
 266   _result = _loader_data->metaspace_non_null()->allocate(_size, _mdtype);
 267   if (_result != NULL) {
 268     return;
 269   }
 270 
 271   // If still failing, allow the Metaspace to expand.
 272   // See delta_capacity_until_GC() for explanation of the
 273   // amount of the expansion.
 274   // This should work unless there really is no more space
 275   // or a MaxMetaspaceSize has been specified on the command line.
 276   _result = _loader_data->metaspace_non_null()->expand_and_allocate(_size, _mdtype);
 277   if (_result != NULL) {
 278     return;
 279   }
 280 
 281   // If expansion failed, do a last-ditch collection and try allocating
 282   // again.  A last-ditch collection will clear softrefs.  This
 283   // behavior is similar to the last-ditch collection done for perm
 284   // gen when it was full and a collection for failed allocation
 285   // did not free perm gen space.
 286   heap->collect_as_vm_thread(GCCause::_last_ditch_collection);
 287   _result = _loader_data->metaspace_non_null()->allocate(_size, _mdtype);
 288   if (_result != NULL) {
 289     return;
 290   }
 291 
 292   if (Verbose && PrintGCDetails) {
 293     gclog_or_tty->print_cr("\nAfter Metaspace GC failed to allocate size "
 294                            SIZE_FORMAT, _size);
 295   }
 296 
 297   if (GC_locker::is_active_and_needs_gc()) {
 298     set_gc_locked();
 299   }
 300 }