src/share/vm/memory/sharedHeap.cpp

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

*** 1,7 ****
  /*
!  * Copyright (c) 2000, 2011, Oracle and/or its affiliates. All rights reserved.
   * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   *
   * This code is free software; you can redistribute it and/or modify it
   * under the terms of the GNU General Public License version 2 only, as
   * published by the Free Software Foundation.
--- 1,7 ----
  /*
!  * Copyright (c) 2000, 2013, Oracle and/or its affiliates. All rights reserved.
   * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   *
   * This code is free software; you can redistribute it and/or modify it
   * under the terms of the GNU General Public License version 2 only, as
   * published by the Free Software Foundation.
*** 44,54 ****
    SH_PS_ObjectSynchronizer_oops_do,
    SH_PS_FlatProfiler_oops_do,
    SH_PS_Management_oops_do,
    SH_PS_SystemDictionary_oops_do,
    SH_PS_jvmti_oops_do,
-   SH_PS_StringTable_oops_do,
    SH_PS_CodeCache_oops_do,
    // Leave this one last.
    SH_PS_NumElements
  };
  
--- 44,53 ----
*** 133,142 ****
--- 132,143 ----
  SharedHeap::StrongRootsScope::StrongRootsScope(SharedHeap* outer, bool activate)
    : MarkScope(activate)
  {
    if (_active) {
      outer->change_strong_roots_parity();
+     // Zero the claimed high water mark in the StringTable
+     StringTable::clear_parallel_claimed_index();
    }
  }
  
  SharedHeap::StrongRootsScope::~StrongRootsScope() {
    // nothing particular
*** 161,176 ****
      perm_gen()->ref_processor()->weak_oops_do(roots);
    }
    // Global (strong) JNI handles
    if (!_process_strong_tasks->is_task_claimed(SH_PS_JNIHandles_oops_do))
      JNIHandles::oops_do(roots);
    // All threads execute this; the individual threads are task groups.
!   if (ParallelGCThreads > 0) {
      Threads::possibly_parallel_oops_do(roots, code_roots);
    } else {
      Threads::oops_do(roots, code_roots);
    }
    if (!_process_strong_tasks-> is_task_claimed(SH_PS_ObjectSynchronizer_oops_do))
      ObjectSynchronizer::oops_do(roots);
    if (!_process_strong_tasks->is_task_claimed(SH_PS_FlatProfiler_oops_do))
      FlatProfiler::oops_do(roots);
    if (!_process_strong_tasks->is_task_claimed(SH_PS_Management_oops_do))
--- 162,179 ----
      perm_gen()->ref_processor()->weak_oops_do(roots);
    }
    // Global (strong) JNI handles
    if (!_process_strong_tasks->is_task_claimed(SH_PS_JNIHandles_oops_do))
      JNIHandles::oops_do(roots);
+ 
    // All threads execute this; the individual threads are task groups.
!   if (CollectedHeap::use_parallel_gc_threads()) {
      Threads::possibly_parallel_oops_do(roots, code_roots);
    } else {
      Threads::oops_do(roots, code_roots);
    }
+ 
    if (!_process_strong_tasks-> is_task_claimed(SH_PS_ObjectSynchronizer_oops_do))
      ObjectSynchronizer::oops_do(roots);
    if (!_process_strong_tasks->is_task_claimed(SH_PS_FlatProfiler_oops_do))
      FlatProfiler::oops_do(roots);
    if (!_process_strong_tasks->is_task_claimed(SH_PS_Management_oops_do))
*** 184,199 ****
      } else if (so & SO_SystemClasses) {
        SystemDictionary::always_strong_oops_do(roots);
      }
    }
  
!   if (!_process_strong_tasks->is_task_claimed(SH_PS_StringTable_oops_do)) {
      if (so & SO_Strings || (!collecting_perm_gen && !JavaObjectsInPerm)) {
        StringTable::oops_do(roots);
      }
      if (JavaObjectsInPerm) {
        // Verify the string table contents are in the perm gen
        NOT_PRODUCT(StringTable::oops_do(&assert_is_perm_closure));
      }
    }
  
    if (!_process_strong_tasks->is_task_claimed(SH_PS_CodeCache_oops_do)) {
--- 187,210 ----
      } else if (so & SO_SystemClasses) {
        SystemDictionary::always_strong_oops_do(roots);
      }
    }
  
!   // All threads execute the following. A specific chunk of buckets
!   // from the StringTable are the individual tasks.
    if (so & SO_Strings || (!collecting_perm_gen && !JavaObjectsInPerm)) {
+     if (CollectedHeap::use_parallel_gc_threads()) {
+       StringTable::possibly_parallel_oops_do(roots);
+     } else {
        StringTable::oops_do(roots);
      }
+   }
    if (JavaObjectsInPerm) {
      // Verify the string table contents are in the perm gen
+     if (CollectedHeap::use_parallel_gc_threads()) {
+       NOT_PRODUCT(StringTable::possibly_parallel_oops_do(&assert_is_perm_closure));
+     } else {
        NOT_PRODUCT(StringTable::oops_do(&assert_is_perm_closure));
      }
    }
  
    if (!_process_strong_tasks->is_task_claimed(SH_PS_CodeCache_oops_do)) {