src/share/vm/memory/sharedHeap.cpp

Print this page
rev 4551 : 8015237: Parallelize string table scanning during strong root processing
Summary: Parallelize the scanning of the intern string table by having each GC worker claim a given number of buckets. Changes were also reviewed by Per Liden <per.liden@oracle.com>.
Reviewed-by: tschatzl, stefank, twisti
   1 /*
   2  * Copyright (c) 2000, 2011, 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  *


  29 #include "gc_interface/collectedHeap.inline.hpp"
  30 #include "memory/sharedHeap.hpp"
  31 #include "oops/oop.inline.hpp"
  32 #include "runtime/fprofiler.hpp"
  33 #include "runtime/java.hpp"
  34 #include "services/management.hpp"
  35 #include "utilities/copy.hpp"
  36 #include "utilities/workgroup.hpp"
  37 
  38 SharedHeap* SharedHeap::_sh;
  39 
  40 // The set of potentially parallel tasks in strong root scanning.
  41 enum SH_process_strong_roots_tasks {
  42   SH_PS_Universe_oops_do,
  43   SH_PS_JNIHandles_oops_do,
  44   SH_PS_ObjectSynchronizer_oops_do,
  45   SH_PS_FlatProfiler_oops_do,
  46   SH_PS_Management_oops_do,
  47   SH_PS_SystemDictionary_oops_do,
  48   SH_PS_jvmti_oops_do,
  49   SH_PS_StringTable_oops_do,
  50   SH_PS_CodeCache_oops_do,
  51   // Leave this one last.
  52   SH_PS_NumElements
  53 };
  54 
  55 SharedHeap::SharedHeap(CollectorPolicy* policy_) :
  56   CollectedHeap(),
  57   _collector_policy(policy_),
  58   _perm_gen(NULL), _rem_set(NULL),
  59   _strong_roots_parity(0),
  60   _process_strong_tasks(new SubTasksDone(SH_PS_NumElements)),
  61   _workers(NULL)
  62 {
  63   if (_process_strong_tasks == NULL || !_process_strong_tasks->valid()) {
  64     vm_exit_during_initialization("Failed necessary allocation.");
  65   }
  66   _sh = this;  // ch is static, should be set only once.
  67   if ((UseParNewGC ||
  68       (UseConcMarkSweepGC && CMSParallelRemarkEnabled) ||
  69        UseG1GC) &&


 118   virtual void do_oop(narrowOop* p) { ShouldNotReachHere(); }
 119 };
 120 static AssertNonScavengableClosure assert_is_non_scavengable_closure;
 121 #endif
 122 
 123 void SharedHeap::change_strong_roots_parity() {
 124   // Also set the new collection parity.
 125   assert(_strong_roots_parity >= 0 && _strong_roots_parity <= 2,
 126          "Not in range.");
 127   _strong_roots_parity++;
 128   if (_strong_roots_parity == 3) _strong_roots_parity = 1;
 129   assert(_strong_roots_parity >= 1 && _strong_roots_parity <= 2,
 130          "Not in range.");
 131 }
 132 
 133 SharedHeap::StrongRootsScope::StrongRootsScope(SharedHeap* outer, bool activate)
 134   : MarkScope(activate)
 135 {
 136   if (_active) {
 137     outer->change_strong_roots_parity();


 138   }
 139 }
 140 
 141 SharedHeap::StrongRootsScope::~StrongRootsScope() {
 142   // nothing particular
 143 }
 144 
 145 void SharedHeap::process_strong_roots(bool activate_scope,
 146                                       bool collecting_perm_gen,
 147                                       ScanningOption so,
 148                                       OopClosure* roots,
 149                                       CodeBlobClosure* code_roots,
 150                                       OopsInGenClosure* perm_blk) {
 151   StrongRootsScope srs(this, activate_scope);
 152   // General strong roots.
 153   assert(_strong_roots_parity != 0, "must have called prologue code");
 154   // _n_termination for _process_strong_tasks should be set up stream
 155   // in a method not running in a GC worker.  Otherwise the GC worker
 156   // could be trying to change the termination condition while the task
 157   // is executing in another GC worker.
 158   if (!_process_strong_tasks->is_task_claimed(SH_PS_Universe_oops_do)) {
 159     Universe::oops_do(roots);
 160     // Consider perm-gen discovered lists to be strong.
 161     perm_gen()->ref_processor()->weak_oops_do(roots);
 162   }
 163   // Global (strong) JNI handles
 164   if (!_process_strong_tasks->is_task_claimed(SH_PS_JNIHandles_oops_do))
 165     JNIHandles::oops_do(roots);

 166   // All threads execute this; the individual threads are task groups.
 167   if (ParallelGCThreads > 0) {
 168     Threads::possibly_parallel_oops_do(roots, code_roots);
 169   } else {
 170     Threads::oops_do(roots, code_roots);
 171   }

 172   if (!_process_strong_tasks-> is_task_claimed(SH_PS_ObjectSynchronizer_oops_do))
 173     ObjectSynchronizer::oops_do(roots);
 174   if (!_process_strong_tasks->is_task_claimed(SH_PS_FlatProfiler_oops_do))
 175     FlatProfiler::oops_do(roots);
 176   if (!_process_strong_tasks->is_task_claimed(SH_PS_Management_oops_do))
 177     Management::oops_do(roots);
 178   if (!_process_strong_tasks->is_task_claimed(SH_PS_jvmti_oops_do))
 179     JvmtiExport::oops_do(roots);
 180 
 181   if (!_process_strong_tasks->is_task_claimed(SH_PS_SystemDictionary_oops_do)) {
 182     if (so & SO_AllClasses) {
 183       SystemDictionary::oops_do(roots);
 184     } else if (so & SO_SystemClasses) {
 185       SystemDictionary::always_strong_oops_do(roots);
 186     }
 187   }
 188 
 189   if (!_process_strong_tasks->is_task_claimed(SH_PS_StringTable_oops_do)) {

 190     if (so & SO_Strings || (!collecting_perm_gen && !JavaObjectsInPerm)) {



 191       StringTable::oops_do(roots);
 192     }

 193     if (JavaObjectsInPerm) {
 194       // Verify the string table contents are in the perm gen



 195       NOT_PRODUCT(StringTable::oops_do(&assert_is_perm_closure));
 196     }
 197   }
 198 
 199   if (!_process_strong_tasks->is_task_claimed(SH_PS_CodeCache_oops_do)) {
 200     if (so & SO_CodeCache) {
 201       // (Currently, CMSCollector uses this to do intermediate-strength collections.)
 202       assert(collecting_perm_gen, "scanning all of code cache");
 203       assert(code_roots != NULL, "must supply closure for code cache");
 204       if (code_roots != NULL) {
 205         CodeCache::blobs_do(code_roots);
 206       }
 207     } else if (so & (SO_SystemClasses|SO_AllClasses)) {
 208       if (!collecting_perm_gen) {
 209         // If we are collecting from class statics, but we are not going to
 210         // visit all of the CodeCache, collect from the non-perm roots if any.
 211         // This makes the code cache function temporarily as a source of strong
 212         // roots for oops, until the next major collection.
 213         //
 214         // If collecting_perm_gen is true, we require that this phase will call


   1 /*
   2  * Copyright (c) 2000, 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  *


  29 #include "gc_interface/collectedHeap.inline.hpp"
  30 #include "memory/sharedHeap.hpp"
  31 #include "oops/oop.inline.hpp"
  32 #include "runtime/fprofiler.hpp"
  33 #include "runtime/java.hpp"
  34 #include "services/management.hpp"
  35 #include "utilities/copy.hpp"
  36 #include "utilities/workgroup.hpp"
  37 
  38 SharedHeap* SharedHeap::_sh;
  39 
  40 // The set of potentially parallel tasks in strong root scanning.
  41 enum SH_process_strong_roots_tasks {
  42   SH_PS_Universe_oops_do,
  43   SH_PS_JNIHandles_oops_do,
  44   SH_PS_ObjectSynchronizer_oops_do,
  45   SH_PS_FlatProfiler_oops_do,
  46   SH_PS_Management_oops_do,
  47   SH_PS_SystemDictionary_oops_do,
  48   SH_PS_jvmti_oops_do,

  49   SH_PS_CodeCache_oops_do,
  50   // Leave this one last.
  51   SH_PS_NumElements
  52 };
  53 
  54 SharedHeap::SharedHeap(CollectorPolicy* policy_) :
  55   CollectedHeap(),
  56   _collector_policy(policy_),
  57   _perm_gen(NULL), _rem_set(NULL),
  58   _strong_roots_parity(0),
  59   _process_strong_tasks(new SubTasksDone(SH_PS_NumElements)),
  60   _workers(NULL)
  61 {
  62   if (_process_strong_tasks == NULL || !_process_strong_tasks->valid()) {
  63     vm_exit_during_initialization("Failed necessary allocation.");
  64   }
  65   _sh = this;  // ch is static, should be set only once.
  66   if ((UseParNewGC ||
  67       (UseConcMarkSweepGC && CMSParallelRemarkEnabled) ||
  68        UseG1GC) &&


 117   virtual void do_oop(narrowOop* p) { ShouldNotReachHere(); }
 118 };
 119 static AssertNonScavengableClosure assert_is_non_scavengable_closure;
 120 #endif
 121 
 122 void SharedHeap::change_strong_roots_parity() {
 123   // Also set the new collection parity.
 124   assert(_strong_roots_parity >= 0 && _strong_roots_parity <= 2,
 125          "Not in range.");
 126   _strong_roots_parity++;
 127   if (_strong_roots_parity == 3) _strong_roots_parity = 1;
 128   assert(_strong_roots_parity >= 1 && _strong_roots_parity <= 2,
 129          "Not in range.");
 130 }
 131 
 132 SharedHeap::StrongRootsScope::StrongRootsScope(SharedHeap* outer, bool activate)
 133   : MarkScope(activate)
 134 {
 135   if (_active) {
 136     outer->change_strong_roots_parity();
 137     // Zero the claimed high water mark in the StringTable
 138     StringTable::clear_parallel_claimed_index();
 139   }
 140 }
 141 
 142 SharedHeap::StrongRootsScope::~StrongRootsScope() {
 143   // nothing particular
 144 }
 145 
 146 void SharedHeap::process_strong_roots(bool activate_scope,
 147                                       bool collecting_perm_gen,
 148                                       ScanningOption so,
 149                                       OopClosure* roots,
 150                                       CodeBlobClosure* code_roots,
 151                                       OopsInGenClosure* perm_blk) {
 152   StrongRootsScope srs(this, activate_scope);
 153   // General strong roots.
 154   assert(_strong_roots_parity != 0, "must have called prologue code");
 155   // _n_termination for _process_strong_tasks should be set up stream
 156   // in a method not running in a GC worker.  Otherwise the GC worker
 157   // could be trying to change the termination condition while the task
 158   // is executing in another GC worker.
 159   if (!_process_strong_tasks->is_task_claimed(SH_PS_Universe_oops_do)) {
 160     Universe::oops_do(roots);
 161     // Consider perm-gen discovered lists to be strong.
 162     perm_gen()->ref_processor()->weak_oops_do(roots);
 163   }
 164   // Global (strong) JNI handles
 165   if (!_process_strong_tasks->is_task_claimed(SH_PS_JNIHandles_oops_do))
 166     JNIHandles::oops_do(roots);
 167 
 168   // All threads execute this; the individual threads are task groups.
 169   if (CollectedHeap::use_parallel_gc_threads()) {
 170     Threads::possibly_parallel_oops_do(roots, code_roots);
 171   } else {
 172     Threads::oops_do(roots, code_roots);
 173   }
 174 
 175   if (!_process_strong_tasks-> is_task_claimed(SH_PS_ObjectSynchronizer_oops_do))
 176     ObjectSynchronizer::oops_do(roots);
 177   if (!_process_strong_tasks->is_task_claimed(SH_PS_FlatProfiler_oops_do))
 178     FlatProfiler::oops_do(roots);
 179   if (!_process_strong_tasks->is_task_claimed(SH_PS_Management_oops_do))
 180     Management::oops_do(roots);
 181   if (!_process_strong_tasks->is_task_claimed(SH_PS_jvmti_oops_do))
 182     JvmtiExport::oops_do(roots);
 183 
 184   if (!_process_strong_tasks->is_task_claimed(SH_PS_SystemDictionary_oops_do)) {
 185     if (so & SO_AllClasses) {
 186       SystemDictionary::oops_do(roots);
 187     } else if (so & SO_SystemClasses) {
 188       SystemDictionary::always_strong_oops_do(roots);
 189     }
 190   }
 191 
 192   // All threads execute the following. A specific chunk of buckets
 193   // from the StringTable are the individual tasks.
 194   if (so & SO_Strings || (!collecting_perm_gen && !JavaObjectsInPerm)) {
 195     if (CollectedHeap::use_parallel_gc_threads()) {
 196       StringTable::possibly_parallel_oops_do(roots);
 197     } else {
 198       StringTable::oops_do(roots);
 199     }
 200   }
 201   if (JavaObjectsInPerm) {
 202     // Verify the string table contents are in the perm gen
 203     if (CollectedHeap::use_parallel_gc_threads()) {
 204       NOT_PRODUCT(StringTable::possibly_parallel_oops_do(&assert_is_perm_closure));
 205     } else {
 206       NOT_PRODUCT(StringTable::oops_do(&assert_is_perm_closure));
 207     }
 208   }
 209 
 210   if (!_process_strong_tasks->is_task_claimed(SH_PS_CodeCache_oops_do)) {
 211     if (so & SO_CodeCache) {
 212       // (Currently, CMSCollector uses this to do intermediate-strength collections.)
 213       assert(collecting_perm_gen, "scanning all of code cache");
 214       assert(code_roots != NULL, "must supply closure for code cache");
 215       if (code_roots != NULL) {
 216         CodeCache::blobs_do(code_roots);
 217       }
 218     } else if (so & (SO_SystemClasses|SO_AllClasses)) {
 219       if (!collecting_perm_gen) {
 220         // If we are collecting from class statics, but we are not going to
 221         // visit all of the CodeCache, collect from the non-perm roots if any.
 222         // This makes the code cache function temporarily as a source of strong
 223         // roots for oops, until the next major collection.
 224         //
 225         // If collecting_perm_gen is true, we require that this phase will call