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  *
  23  */
  24 
  25 #include "precompiled.hpp"
  26 #include "classfile/symbolTable.hpp"
  27 #include "classfile/systemDictionary.hpp"
  28 #include "code/codeCache.hpp"
  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_ClassLoaderDataGraph_oops_do,
  49   SH_PS_jvmti_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   _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) &&
  70       ParallelGCThreads > 0) {
  71     _workers = new FlexibleWorkGang("Parallel GC Threads", ParallelGCThreads,
  72                             /* are_GC_task_threads */true,
  73                             /* are_ConcurrentGC_threads */false);
  74     if (_workers == NULL) {
  75       vm_exit_during_initialization("Failed necessary allocation.");
  76     } else {
  77       _workers->initialize_workers();
  78     }
  79   }
  80 }
  81 
  82 int SharedHeap::n_termination() {
  83   return _process_strong_tasks->n_threads();
  84 }
  85 
  86 void SharedHeap::set_n_termination(int t) {
  87   _process_strong_tasks->set_n_threads(t);
  88 }
  89 
  90 bool SharedHeap::heap_lock_held_for_gc() {
  91   Thread* t = Thread::current();
  92   return    Heap_lock->owned_by_self()
  93          || (   (t->is_GC_task_thread() ||  t->is_VM_thread())
  94              && _thread_holds_heap_lock_for_gc);
  95 }
  96 
  97 void SharedHeap::set_par_threads(uint t) {
  98   assert(t == 0 || !UseSerialGC, "Cannot have parallel threads");
  99   _n_par_threads = t;
 100   _process_strong_tasks->set_n_threads(t);
 101 }
 102 
 103 #ifdef ASSERT
 104 class AssertNonScavengableClosure: public OopClosure {
 105 public:
 106   virtual void do_oop(oop* p) {
 107     assert(!Universe::heap()->is_in_partial_collection(*p),
 108       "Referent should not be scavengable.");  }
 109   virtual void do_oop(narrowOop* p) { ShouldNotReachHere(); }
 110 };
 111 static AssertNonScavengableClosure assert_is_non_scavengable_closure;
 112 #endif
 113 
 114 void SharedHeap::change_strong_roots_parity() {
 115   // Also set the new collection parity.
 116   assert(_strong_roots_parity >= 0 && _strong_roots_parity <= 2,
 117          "Not in range.");
 118   _strong_roots_parity++;
 119   if (_strong_roots_parity == 3) _strong_roots_parity = 1;
 120   assert(_strong_roots_parity >= 1 && _strong_roots_parity <= 2,
 121          "Not in range.");
 122 }
 123 
 124 SharedHeap::StrongRootsScope::StrongRootsScope(SharedHeap* outer, bool activate)
 125   : MarkScope(activate)
 126 {
 127   if (_active) {
 128     outer->change_strong_roots_parity();
 129     // Zero the claimed high water mark in the StringTable
 130     StringTable::clear_par_claimed_index();
 131   }
 132 }
 133 
 134 SharedHeap::StrongRootsScope::~StrongRootsScope() {
 135   // nothing particular
 136 }
 137 
 138 void SharedHeap::process_strong_roots(bool activate_scope,
 139                                       bool is_scavenging,
 140                                       ScanningOption so,
 141                                       OopClosure* roots,
 142                                       CodeBlobClosure* code_roots,
 143                                       KlassClosure* klass_closure) {
 144   StrongRootsScope srs(this, activate_scope);
 145 
 146   // General strong roots.
 147   assert(_strong_roots_parity != 0, "must have called prologue code");
 148   // _n_termination for _process_strong_tasks should be set up stream
 149   // in a method not running in a GC worker.  Otherwise the GC worker
 150   // could be trying to change the termination condition while the task
 151   // is executing in another GC worker.
 152   if (!_process_strong_tasks->is_task_claimed(SH_PS_Universe_oops_do)) {
 153     Universe::oops_do(roots);
 154   }
 155   // Global (strong) JNI handles
 156   if (!_process_strong_tasks->is_task_claimed(SH_PS_JNIHandles_oops_do))
 157     JNIHandles::oops_do(roots);
 158 
 159   // All threads execute this; the individual threads are task groups.
 160   CLDToOopClosure roots_from_clds(roots);
 161   CLDToOopClosure* roots_from_clds_p = (is_scavenging ? NULL : &roots_from_clds);
 162   if (CollectedHeap::use_parallel_gc_threads()) {
 163     Threads::possibly_parallel_oops_do(roots, roots_from_clds_p, code_roots);
 164   } else {
 165     Threads::oops_do(roots, roots_from_clds_p, code_roots);
 166   }
 167 
 168   if (!_process_strong_tasks-> is_task_claimed(SH_PS_ObjectSynchronizer_oops_do))
 169     ObjectSynchronizer::oops_do(roots);
 170   if (!_process_strong_tasks->is_task_claimed(SH_PS_FlatProfiler_oops_do))
 171     FlatProfiler::oops_do(roots);
 172   if (!_process_strong_tasks->is_task_claimed(SH_PS_Management_oops_do))
 173     Management::oops_do(roots);
 174   if (!_process_strong_tasks->is_task_claimed(SH_PS_jvmti_oops_do))
 175     JvmtiExport::oops_do(roots);
 176 
 177   if (!_process_strong_tasks->is_task_claimed(SH_PS_SystemDictionary_oops_do)) {
 178     if (so & SO_AllClasses) {
 179       SystemDictionary::oops_do(roots);
 180     } else if (so & SO_SystemClasses) {
 181       SystemDictionary::always_strong_oops_do(roots);
 182     } else {
 183       fatal("We should always have selected either SO_AllClasses or SO_SystemClasses");
 184     }
 185   }
 186 
 187   if (!_process_strong_tasks->is_task_claimed(SH_PS_ClassLoaderDataGraph_oops_do)) {
 188     if (so & SO_AllClasses) {
 189       ClassLoaderDataGraph::oops_do(roots, klass_closure, !is_scavenging);
 190     } else if (so & SO_SystemClasses) {
 191       ClassLoaderDataGraph::always_strong_oops_do(roots, klass_closure, !is_scavenging);
 192     }
 193   }
 194 
 195   // All threads execute the following. A specific chunk of buckets
 196   // from the StringTable are the individual tasks.
 197   if (so & SO_Strings) {
 198     if (CollectedHeap::use_parallel_gc_threads()) {
 199       StringTable::possibly_parallel_oops_do(roots);
 200     } else {
 201       StringTable::oops_do(roots);
 202     }
 203   }
 204 
 205   if (!_process_strong_tasks->is_task_claimed(SH_PS_CodeCache_oops_do)) {
 206     if (so & SO_CodeCache) {
 207       assert(code_roots != NULL, "must supply closure for code cache");
 208 
 209       if (is_scavenging) {
 210         // We only visit parts of the CodeCache when scavenging.
 211         CodeCache::scavenge_root_nmethods_do(code_roots);
 212       } else {
 213         // CMSCollector uses this to do intermediate-strength collections.
 214         // We scan the entire code cache, since CodeCache::do_unloading is not called.
 215         CodeCache::blobs_do(code_roots);
 216       }
 217     }
 218     // Verify that the code cache contents are not subject to
 219     // movement by a scavenging collection.
 220     DEBUG_ONLY(CodeBlobToOopClosure assert_code_is_non_scavengable(&assert_is_non_scavengable_closure, /*do_marking=*/ false));
 221     DEBUG_ONLY(CodeCache::asserted_non_scavengable_nmethods_do(&assert_code_is_non_scavengable));
 222   }
 223 
 224   _process_strong_tasks->all_tasks_completed();
 225 }
 226 
 227 class AlwaysTrueClosure: public BoolObjectClosure {
 228 public:
 229   bool do_object_b(oop p) { return true; }
 230 };
 231 static AlwaysTrueClosure always_true;
 232 
 233 void SharedHeap::process_weak_roots(OopClosure* root_closure,
 234                                     CodeBlobClosure* code_roots) {
 235   // Global (weak) JNI handles
 236   JNIHandles::weak_oops_do(&always_true, root_closure);
 237 
 238   CodeCache::blobs_do(code_roots);
 239   StringTable::oops_do(root_closure);
 240 }
 241 
 242 void SharedHeap::set_barrier_set(BarrierSet* bs) {
 243   _barrier_set = bs;
 244   // Cached barrier set for fast access in oops
 245   oopDesc::set_bs(bs);
 246 }
 247 
 248 void SharedHeap::post_initialize() {
 249   ref_processing_init();
 250 }
 251 
 252 void SharedHeap::ref_processing_init() {}
 253 
 254 // Some utilities.
 255 void SharedHeap::print_size_transition(outputStream* out,
 256                                        size_t bytes_before,
 257                                        size_t bytes_after,
 258                                        size_t capacity) {
 259   out->print(" %d%s->%d%s(%d%s)",
 260              byte_size_in_proper_unit(bytes_before),
 261              proper_unit_for_byte_size(bytes_before),
 262              byte_size_in_proper_unit(bytes_after),
 263              proper_unit_for_byte_size(bytes_after),
 264              byte_size_in_proper_unit(capacity),
 265              proper_unit_for_byte_size(capacity));
 266 }