src/share/vm/gc_implementation/parallelScavenge/pcTasks.hpp

Thu, 22 Sep 2011 10:57:37 -0700

author
johnc
date
Thu, 22 Sep 2011 10:57:37 -0700
changeset 3175
4dfb2df418f2
parent 3115
c2bf0120ee5d
child 5194
eda078b01c65
permissions
-rw-r--r--

6484982: G1: process references during evacuation pauses
Summary: G1 now uses two reference processors - one is used by concurrent marking and the other is used by STW GCs (both full and incremental evacuation pauses). In an evacuation pause, the reference processor is embedded into the closures used to scan objects. Doing so causes causes reference objects to be 'discovered' by the reference processor. At the end of the evacuation pause, these discovered reference objects are processed - preserving (and copying) referent objects (and their reachable graphs) as appropriate.
Reviewed-by: ysr, jwilhelm, brutisso, stefank, tonyp

     1 /*
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     3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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     6  * under the terms of the GNU General Public License version 2 only, as
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    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).
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    18  *
    19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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    25 #ifndef SHARE_VM_GC_IMPLEMENTATION_PARALLELSCAVENGE_PCTASKS_HPP
    26 #define SHARE_VM_GC_IMPLEMENTATION_PARALLELSCAVENGE_PCTASKS_HPP
    28 #include "gc_implementation/parallelScavenge/gcTaskManager.hpp"
    29 #include "gc_implementation/parallelScavenge/psParallelCompact.hpp"
    30 #include "gc_implementation/parallelScavenge/psTasks.hpp"
    33 // Tasks for parallel compaction of the old generation
    34 //
    35 // Tasks are created and enqueued on a task queue. The
    36 // tasks for parallel old collector for marking objects
    37 // are MarkFromRootsTask and ThreadRootsMarkingTask.
    38 //
    39 // MarkFromRootsTask's are created
    40 // with a root group (e.g., jni_handles) and when the do_it()
    41 // method of a MarkFromRootsTask is executed, it starts marking
    42 // form it's root group.
    43 //
    44 // ThreadRootsMarkingTask's are created for each Java thread.  When
    45 // the do_it() method of a ThreadRootsMarkingTask is executed, it
    46 // starts marking from the thread's roots.
    47 //
    48 // The enqueuing of the MarkFromRootsTask and ThreadRootsMarkingTask
    49 // do little more than create the task and put it on a queue.  The
    50 // queue is a GCTaskQueue and threads steal tasks from this GCTaskQueue.
    51 //
    52 // In addition to the MarkFromRootsTask and ThreadRootsMarkingTask
    53 // tasks there are StealMarkingTask tasks.  The StealMarkingTask's
    54 // steal a reference from the marking stack of another
    55 // thread and transitively marks the object of the reference
    56 // and internal references.  After successfully stealing a reference
    57 // and marking it, the StealMarkingTask drains its marking stack
    58 // stack before attempting another steal.
    59 //
    60 // ThreadRootsMarkingTask
    61 //
    62 // This task marks from the roots of a single thread. This task
    63 // enables marking of thread roots in parallel.
    64 //
    66 class ParallelTaskTerminator;
    68 class ThreadRootsMarkingTask : public GCTask {
    69  private:
    70   JavaThread* _java_thread;
    71   VMThread* _vm_thread;
    72  public:
    73   ThreadRootsMarkingTask(JavaThread* root) : _java_thread(root), _vm_thread(NULL) {}
    74   ThreadRootsMarkingTask(VMThread* root) : _java_thread(NULL), _vm_thread(root) {}
    76   char* name() { return (char *)"thread-roots-marking-task"; }
    78   virtual void do_it(GCTaskManager* manager, uint which);
    79 };
    82 //
    83 // MarkFromRootsTask
    84 //
    85 // This task marks from all the roots to all live
    86 // objects.
    87 //
    88 //
    90 class MarkFromRootsTask : public GCTask {
    91  public:
    92   enum RootType {
    93     universe              = 1,
    94     jni_handles           = 2,
    95     threads               = 3,
    96     object_synchronizer   = 4,
    97     flat_profiler         = 5,
    98     management            = 6,
    99     jvmti                 = 7,
   100     system_dictionary     = 8,
   101     code_cache            = 9
   102   };
   103  private:
   104   RootType _root_type;
   105  public:
   106   MarkFromRootsTask(RootType value) : _root_type(value) {}
   108   char* name() { return (char *)"mark-from-roots-task"; }
   110   virtual void do_it(GCTaskManager* manager, uint which);
   111 };
   113 //
   114 // RefProcTaskProxy
   115 //
   116 // This task is used as a proxy to parallel reference processing tasks .
   117 //
   119 class RefProcTaskProxy : public GCTask {
   120   typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
   121   ProcessTask & _rp_task;
   122   uint          _work_id;
   123 public:
   124   RefProcTaskProxy(ProcessTask & rp_task, uint work_id)
   125     : _rp_task(rp_task),
   126       _work_id(work_id)
   127   { }
   129 private:
   130   virtual char* name() { return (char *)"Process referents by policy in parallel"; }
   132   virtual void do_it(GCTaskManager* manager, uint which);
   133 };
   137 //
   138 // RefEnqueueTaskProxy
   139 //
   140 // This task is used as a proxy to parallel reference processing tasks .
   141 //
   143 class RefEnqueueTaskProxy: public GCTask {
   144   typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
   145   EnqueueTask& _enq_task;
   146   uint         _work_id;
   148 public:
   149   RefEnqueueTaskProxy(EnqueueTask& enq_task, uint work_id)
   150     : _enq_task(enq_task),
   151       _work_id(work_id)
   152   { }
   154   virtual char* name() { return (char *)"Enqueue reference objects in parallel"; }
   155   virtual void do_it(GCTaskManager* manager, uint which)
   156   {
   157     _enq_task.work(_work_id);
   158   }
   159 };
   162 //
   163 // RefProcTaskExecutor
   164 //
   165 // Task executor is an interface for the reference processor to run
   166 // tasks using GCTaskManager.
   167 //
   169 class RefProcTaskExecutor: public AbstractRefProcTaskExecutor {
   170   virtual void execute(ProcessTask& task);
   171   virtual void execute(EnqueueTask& task);
   172 };
   175 //
   176 // StealMarkingTask
   177 //
   178 // This task is used to distribute work to idle threads.
   179 //
   181 class StealMarkingTask : public GCTask {
   182  private:
   183    ParallelTaskTerminator* const _terminator;
   184  private:
   186  public:
   187   char* name() { return (char *)"steal-marking-task"; }
   189   StealMarkingTask(ParallelTaskTerminator* t);
   191   ParallelTaskTerminator* terminator() { return _terminator; }
   193   virtual void do_it(GCTaskManager* manager, uint which);
   194 };
   196 //
   197 // StealRegionCompactionTask
   198 //
   199 // This task is used to distribute work to idle threads.
   200 //
   202 class StealRegionCompactionTask : public GCTask {
   203  private:
   204    ParallelTaskTerminator* const _terminator;
   205  public:
   206   StealRegionCompactionTask(ParallelTaskTerminator* t);
   208   char* name() { return (char *)"steal-region-task"; }
   209   ParallelTaskTerminator* terminator() { return _terminator; }
   211   virtual void do_it(GCTaskManager* manager, uint which);
   212 };
   214 //
   215 // UpdateDensePrefixTask
   216 //
   217 // This task is used to update the dense prefix
   218 // of a space.
   219 //
   221 class UpdateDensePrefixTask : public GCTask {
   222  private:
   223   PSParallelCompact::SpaceId _space_id;
   224   size_t _region_index_start;
   225   size_t _region_index_end;
   227  public:
   228   char* name() { return (char *)"update-dense_prefix-task"; }
   230   UpdateDensePrefixTask(PSParallelCompact::SpaceId space_id,
   231                         size_t region_index_start,
   232                         size_t region_index_end);
   234   virtual void do_it(GCTaskManager* manager, uint which);
   235 };
   237 //
   238 // DrainStacksCompactionTask
   239 //
   240 // This task processes regions that have been added to the stacks of each
   241 // compaction manager.
   242 //
   243 // Trying to use one draining thread does not work because there are no
   244 // guarantees about which task will be picked up by which thread.  For example,
   245 // if thread A gets all the preloaded regions, thread A may not get a draining
   246 // task (they may all be done by other threads).
   247 //
   249 class DrainStacksCompactionTask : public GCTask {
   250  uint _stack_index;
   251  uint stack_index() { return _stack_index; }
   252  public:
   253   DrainStacksCompactionTask(uint stack_index) : GCTask(),
   254                                                 _stack_index(stack_index) {};
   255   char* name() { return (char *)"drain-region-task"; }
   256   virtual void do_it(GCTaskManager* manager, uint which);
   257 };
   259 #endif // SHARE_VM_GC_IMPLEMENTATION_PARALLELSCAVENGE_PCTASKS_HPP

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