C++ (Cpp) Klass::set_biased_lock_revocation_count Examples

Example #1

File: biasedLocking.cpp Project: gaoxiaojun/dync

static HeuristicsResult update_heuristics(oop o, bool allow_rebias) {
  markOop mark = o->mark();
  if (!mark->has_bias_pattern()) {
    return HR_NOT_BIASED;
  }

  // Heuristics to attempt to throttle the number of revocations.
  // Stages:
  // 1. Revoke the biases of all objects in the heap of this type,
  //    but allow rebiasing of those objects if unlocked.
  // 2. Revoke the biases of all objects in the heap of this type
  //    and don't allow rebiasing of these objects. Disable
  //    allocation of objects of that type with the bias bit set.
  Klass* k = o->klass();
  jlong cur_time = os::javaTimeMillis();
  jlong last_bulk_revocation_time = k->last_biased_lock_bulk_revocation_time();
  int revocation_count = k->biased_lock_revocation_count();
  if ((revocation_count >= BiasedLockingBulkRebiasThreshold) &&
      (revocation_count <  BiasedLockingBulkRevokeThreshold) &&
      (last_bulk_revocation_time != 0) &&
      (cur_time - last_bulk_revocation_time >= BiasedLockingDecayTime)) {
    // This is the first revocation we've seen in a while of an
    // object of this type since the last time we performed a bulk
    // rebiasing operation. The application is allocating objects in
    // bulk which are biased toward a thread and then handing them
    // off to another thread. We can cope with this allocation
    // pattern via the bulk rebiasing mechanism so we reset the
    // klass's revocation count rather than allow it to increase
    // monotonically. If we see the need to perform another bulk
    // rebias operation later, we will, and if subsequently we see
    // many more revocation operations in a short period of time we
    // will completely disable biasing for this type.
    k->set_biased_lock_revocation_count(0);
    revocation_count = 0;
  }

  // Make revocation count saturate just beyond BiasedLockingBulkRevokeThreshold
  if (revocation_count <= BiasedLockingBulkRevokeThreshold) {
    revocation_count = k->atomic_incr_biased_lock_revocation_count();
  }

  if (revocation_count == BiasedLockingBulkRevokeThreshold) {
    return HR_BULK_REVOKE;
  }

  if (revocation_count == BiasedLockingBulkRebiasThreshold) {
    return HR_BULK_REBIAS;
  }

  return HR_SINGLE_REVOKE;
}

Example #2

File: klass.cpp Project: sxhao/codenameone-avian

klassOop Klass::base_create_klass_oop(KlassHandle& klass, int size,
                                      const Klass_vtbl& vtbl, TRAPS) {
  size = align_object_size(size);
  // allocate and initialize vtable
  Klass*   kl = (Klass*) vtbl.allocate_permanent(klass, size, CHECK_NULL);
  klassOop k  = kl->as_klassOop();

  { // Preinitialize supertype information.
    // A later call to initialize_supers() may update these settings:
    kl->set_super(NULL);
    for (juint i = 0; i < Klass::primary_super_limit(); i++) {
      kl->_primary_supers[i] = NULL;
    }
    kl->set_secondary_supers(NULL);
    oop_store_without_check((oop*) &kl->_primary_supers[0], k);
    kl->set_super_check_offset(in_bytes(primary_supers_offset()));
  }

  kl->set_java_mirror(NULL);
  kl->set_modifier_flags(0);
  kl->set_layout_helper(Klass::_lh_neutral_value);
  kl->set_name(NULL);
  AccessFlags af;
  af.set_flags(0);
  kl->set_access_flags(af);
  kl->set_subklass(NULL);
  kl->set_next_sibling(NULL);
  kl->set_alloc_count(0);
  kl->set_alloc_size(0);
  TRACE_SET_KLASS_TRACE_ID(kl, 0);

  kl->set_prototype_header(markOopDesc::prototype());
  kl->set_biased_lock_revocation_count(0);
  kl->set_last_biased_lock_bulk_revocation_time(0);

  return k;
}