hotspot/src/share/vm/gc_implementation/concurrentMarkSweep/cmsPermGen.cpp
author ysr
Thu, 21 Oct 2010 17:29:24 -0700
changeset 6984 c6718f921eb6
parent 6765 f8d7d46aa4ff
child 7397 5b173b4ca846
permissions -rw-r--r--
6992998: CMSWaitDuration=0 causes hangs with +ExplicitGCInvokesConcurrent Summary: Closed a timing hole during which concurrent full gc requests can be missed. The hole can increase the latency of the response to a full gc request by up to the value of CMSWaitDuration. If CMSWaitDuration=0 is, as currently, interpreted as an unbounded wait, suitable in certain tuning scenarios, the application can potentially hang. Made two obscure tunables, including CMSWaitDuration, manageable. Reviewed-by: jcoomes, tonyp

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#include "incls/_precompiled.incl"
#include "incls/_cmsPermGen.cpp.incl"

CMSPermGen::CMSPermGen(ReservedSpace rs, size_t initial_byte_size,
             CardTableRS* ct,
             FreeBlockDictionary::DictionaryChoice dictionaryChoice) {
  CMSPermGenGen* g =
    new CMSPermGenGen(rs, initial_byte_size, -1, ct);
  if (g == NULL) {
    vm_exit_during_initialization("Could not allocate a CompactingPermGen");
  }

  g->initialize_performance_counters();

  _gen = g;
}

HeapWord* CMSPermGen::mem_allocate(size_t size) {
  Mutex* lock = _gen->freelistLock();
  bool lock_owned = lock->owned_by_self();
  if (lock_owned) {
    MutexUnlocker mul(lock);
    return mem_allocate_in_gen(size, _gen);
  } else {
    return mem_allocate_in_gen(size, _gen);
  }
}

HeapWord* CMSPermGen::request_expand_and_allocate(Generation* gen,
                                                  size_t size,
                                                  GCCause::Cause prev_cause /* ignored */) {
  HeapWord* obj = gen->expand_and_allocate(size, false);
  if (gen->capacity() >= _capacity_expansion_limit) {
    set_capacity_expansion_limit(gen->capacity() + MaxPermHeapExpansion);
    assert(((ConcurrentMarkSweepGeneration*)gen)->should_concurrent_collect(),
           "Should kick off a collection if one not in progress");
  }
  return obj;
}

void CMSPermGen::compute_new_size() {
  _gen->compute_new_size();
}

void CMSPermGenGen::initialize_performance_counters() {

  const char* gen_name = "perm";

  // Generation Counters - generation 2, 1 subspace
  _gen_counters = new GenerationCounters(gen_name, 2, 1, &_virtual_space);

  _gc_counters = NULL;

  _space_counters = new GSpaceCounters(gen_name, 0,
                                       _virtual_space.reserved_size(),
                                       this, _gen_counters);
}