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/shared/gcLocker.inline.hpp"

    29 #include "gc/shared/genCollectedHeap.hpp"

    30 #include "gc/shared/vmGCOperations.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/macros.hpp"

    39 #include "utilities/preserveException.hpp"

    40 #if INCLUDE_ALL_GCS

    41 #include "gc/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::skip_operation() const {

   132   return false;

   133 }

   134 

   135 bool VM_GC_HeapInspection::collect() {

   136   if (GC_locker::is_active()) {

   137     return false;

   138   }

   139   Universe::heap()->collect_as_vm_thread(GCCause::_heap_inspection);

   140   return true;

   141 }

   142 

   143 void VM_GC_HeapInspection::doit() {

   144   HandleMark hm;

   145   Universe::heap()->ensure_parsability(false); // must happen, even if collection does

   146                                                // not happen (e.g. due to GC_locker)

   147                                                // or _full_gc being false

   148   if (_full_gc) {

   149     if (!collect()) {

   150       // The collection attempt was skipped because the gc locker is held.

   151       // The following dump may then be a tad misleading to someone expecting

   152       // only live objects to show up in the dump (see CR 6944195). Just issue

   153       // a suitable warning in that case and do not attempt to do a collection.

   154       // The latter is a subtle point, because even a failed attempt

   155       // to GC will, in fact, induce one in the future, which we

   156       // probably want to avoid in this case because the GC that we may

   157       // be about to attempt holds value for us only

   158       // if it happens now and not if it happens in the eventual

   159       // future.

   160       warning("GC locker is held; pre-dump GC was skipped");

   161     }

   162   }

   163   HeapInspection inspect(_csv_format, _print_help, _print_class_stats,

   164                          _columns);

   165   inspect.heap_inspection(_out);

   166 }

   167 

   168 

   169 void VM_GenCollectForAllocation::doit() {

   170   SvcGCMarker sgcm(SvcGCMarker::MINOR);

   171 

   172   GenCollectedHeap* gch = GenCollectedHeap::heap();

   173   GCCauseSetter gccs(gch, _gc_cause);

   174   _result = gch->satisfy_failed_allocation(_word_size, _tlab);

   175   assert(gch->is_in_reserved_or_null(_result), "result not in heap");

   176 

   177   if (_result == NULL && GC_locker::is_active_and_needs_gc()) {

   178     set_gc_locked();

   179   }

   180 }

   181 

   182 void VM_GenCollectFull::doit() {

   183   SvcGCMarker sgcm(SvcGCMarker::FULL);

   184 

   185   GenCollectedHeap* gch = GenCollectedHeap::heap();

   186   GCCauseSetter gccs(gch, _gc_cause);

   187   gch->do_full_collection(gch->must_clear_all_soft_refs(), _max_level);

   188 }

   189 

   190 // Returns true iff concurrent GCs unloads metadata.

   191 bool VM_CollectForMetadataAllocation::initiate_concurrent_GC() {

   192 #if INCLUDE_ALL_GCS

   193   if (UseConcMarkSweepGC && CMSClassUnloadingEnabled) {

   194     MetaspaceGC::set_should_concurrent_collect(true);

   195     return true;

   196   }

   197 

   198   if (UseG1GC && ClassUnloadingWithConcurrentMark) {

   199     G1CollectedHeap* g1h = G1CollectedHeap::heap();

   200     g1h->g1_policy()->set_initiate_conc_mark_if_possible();

   201 

   202     GCCauseSetter x(g1h, _gc_cause);

   203 

   204     // At this point we are supposed to start a concurrent cycle. We

   205     // will do so if one is not already in progress.

   206     bool should_start = g1h->g1_policy()->force_initial_mark_if_outside_cycle(_gc_cause);

   207 

   208     if (should_start) {

   209       double pause_target = g1h->g1_policy()->max_pause_time_ms();

   210       g1h->do_collection_pause_at_safepoint(pause_target);

   211     }

   212     return true;

   213   }

   214 #endif

   215 

   216   return false;

   217 }

   218 

   219 static void log_metaspace_alloc_failure_for_concurrent_GC() {

   220   if (Verbose && PrintGCDetails) {

   221     if (UseConcMarkSweepGC) {

   222       gclog_or_tty->print_cr("\nCMS full GC for Metaspace");

   223     } else if (UseG1GC) {

   224       gclog_or_tty->print_cr("\nG1 full GC for Metaspace");

   225     }

   226   }

   227 }

   228 

   229 void VM_CollectForMetadataAllocation::doit() {

   230   SvcGCMarker sgcm(SvcGCMarker::FULL);

   231 

   232   CollectedHeap* heap = Universe::heap();

   233   GCCauseSetter gccs(heap, _gc_cause);

   234 

   235   // Check again if the space is available.  Another thread

   236   // may have similarly failed a metadata allocation and induced

   237   // a GC that freed space for the allocation.

   238   if (!MetadataAllocationFailALot) {

   239     _result = _loader_data->metaspace_non_null()->allocate(_size, _mdtype);

   240     if (_result != NULL) {

   241       return;

   242     }

   243   }

   244 

   245   if (initiate_concurrent_GC()) {

   246     // For CMS and G1 expand since the collection is going to be concurrent.

   247     _result = _loader_data->metaspace_non_null()->expand_and_allocate(_size, _mdtype);

   248     if (_result != NULL) {

   249       return;

   250     }

   251 

   252     log_metaspace_alloc_failure_for_concurrent_GC();

   253   }

   254 

   255   // Don't clear the soft refs yet.

   256   heap->collect_as_vm_thread(GCCause::_metadata_GC_threshold);

   257   // After a GC try to allocate without expanding.  Could fail

   258   // and expansion will be tried below.

   259   _result = _loader_data->metaspace_non_null()->allocate(_size, _mdtype);

   260   if (_result != NULL) {

   261     return;

   262   }

   263 

   264   // If still failing, allow the Metaspace to expand.

   265   // See delta_capacity_until_GC() for explanation of the

   266   // amount of the expansion.

   267   // This should work unless there really is no more space

   268   // or a MaxMetaspaceSize has been specified on the command line.

   269   _result = _loader_data->metaspace_non_null()->expand_and_allocate(_size, _mdtype);

   270   if (_result != NULL) {

   271     return;

   272   }

   273 

   274   // If expansion failed, do a last-ditch collection and try allocating

   275   // again.  A last-ditch collection will clear softrefs.  This

   276   // behavior is similar to the last-ditch collection done for perm

   277   // gen when it was full and a collection for failed allocation

   278   // did not free perm gen space.

   279   heap->collect_as_vm_thread(GCCause::_last_ditch_collection);

   280   _result = _loader_data->metaspace_non_null()->allocate(_size, _mdtype);

   281   if (_result != NULL) {

   282     return;

   283   }

   284 

   285   if (Verbose && PrintGCDetails) {

   286     gclog_or_tty->print_cr("\nAfter Metaspace GC failed to allocate size "

   287                            SIZE_FORMAT, _size);

   288   }

   289 

   290   if (GC_locker::is_active_and_needs_gc()) {

   291     set_gc_locked();

   292   }

   293 }