jdk8-mips64-public/hotspot: src/share/vm/memory/collectorPolicy.cpp@ca0a78017dc7 (annotated)

src/share/vm/memory/collectorPolicy.cpp@ca0a78017dc7 (annotated)

src/share/vm/memory/collectorPolicy.cpp

Sun, 30 Dec 2012 08:47:52 +0100

author: brutisso
date: Sun, 30 Dec 2012 08:47:52 +0100
changeset 4387: ca0a78017dc7
parent 4382: e51c9860cf66
child 4542: db9981fd3124
child 4554: 95ccff9eee8e
permissions: -rw-r--r--

8005396: Use ParNew with only one thread instead of DefNew as default for CMS on single CPU machines
Reviewed-by: jmasa, jcoomes

 /*
  * Copyright (c) 2001, 2012, 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.
  *
  * This code is distributed in the hope that it will be useful, but WITHOUT
  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  * version 2 for more details (a copy is included in the LICENSE file that
  * accompanied this code).
  *
  * You should have received a copy of the GNU General Public License version
  * 2 along with this work; if not, write to the Free Software Foundation,
  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  *
  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  * or visit www.oracle.com if you need additional information or have any
  * questions.
  *
  */
 #include "precompiled.hpp"
 #include "gc_implementation/shared/adaptiveSizePolicy.hpp"
 #include "gc_implementation/shared/gcPolicyCounters.hpp"
 #include "gc_implementation/shared/vmGCOperations.hpp"
 #include "memory/cardTableRS.hpp"
 #include "memory/collectorPolicy.hpp"
 #include "memory/gcLocker.inline.hpp"
 #include "memory/genCollectedHeap.hpp"
 #include "memory/generationSpec.hpp"
 #include "memory/space.hpp"
 #include "memory/universe.hpp"
 #include "runtime/arguments.hpp"
 #include "runtime/globals_extension.hpp"
 #include "runtime/handles.inline.hpp"
 #include "runtime/java.hpp"
 #include "runtime/thread.inline.hpp"
 #include "runtime/vmThread.hpp"
 #ifndef SERIALGC
 #include "gc_implementation/concurrentMarkSweep/cmsAdaptiveSizePolicy.hpp"
 #include "gc_implementation/concurrentMarkSweep/cmsGCAdaptivePolicyCounters.hpp"
 #endif
 // CollectorPolicy methods.
 void CollectorPolicy::initialize_flags() {
   if (MetaspaceSize > MaxMetaspaceSize) {
     MaxMetaspaceSize = MetaspaceSize;
   }
   MetaspaceSize = MAX2(min_alignment(), align_size_down_(MetaspaceSize, min_alignment()));
   // Don't increase Metaspace size limit above specified.
   MaxMetaspaceSize = align_size_down(MaxMetaspaceSize, max_alignment());
   if (MetaspaceSize > MaxMetaspaceSize) {
     MetaspaceSize = MaxMetaspaceSize;
   }
   MinMetaspaceExpansion = MAX2(min_alignment(), align_size_down_(MinMetaspaceExpansion, min_alignment()));
   MaxMetaspaceExpansion = MAX2(min_alignment(), align_size_down_(MaxMetaspaceExpansion, min_alignment()));
   MinHeapDeltaBytes = align_size_up(MinHeapDeltaBytes, min_alignment());
   assert(MetaspaceSize    % min_alignment() == 0, "metapace alignment");
   assert(MaxMetaspaceSize % max_alignment() == 0, "maximum metaspace alignment");
   if (MetaspaceSize < 256*K) {
     vm_exit_during_initialization("Too small initial Metaspace size");
   }
 }
 void CollectorPolicy::initialize_size_info() {
   // User inputs from -mx and ms are aligned
   set_initial_heap_byte_size(InitialHeapSize);
   if (initial_heap_byte_size() == 0) {
     set_initial_heap_byte_size(NewSize + OldSize);
   }
   set_initial_heap_byte_size(align_size_up(_initial_heap_byte_size,
                                            min_alignment()));
   set_min_heap_byte_size(Arguments::min_heap_size());
   if (min_heap_byte_size() == 0) {
     set_min_heap_byte_size(NewSize + OldSize);
   }
   set_min_heap_byte_size(align_size_up(_min_heap_byte_size,
                                        min_alignment()));
   set_max_heap_byte_size(align_size_up(MaxHeapSize, max_alignment()));
   // Check heap parameter properties
   if (initial_heap_byte_size() < M) {
     vm_exit_during_initialization("Too small initial heap");
   }
   // Check heap parameter properties
   if (min_heap_byte_size() < M) {
     vm_exit_during_initialization("Too small minimum heap");
   }
   if (initial_heap_byte_size() <= NewSize) {
      // make sure there is at least some room in old space
     vm_exit_during_initialization("Too small initial heap for new size specified");
   }
   if (max_heap_byte_size() < min_heap_byte_size()) {
     vm_exit_during_initialization("Incompatible minimum and maximum heap sizes specified");
   }
   if (initial_heap_byte_size() < min_heap_byte_size()) {
     vm_exit_during_initialization("Incompatible minimum and initial heap sizes specified");
   }
   if (max_heap_byte_size() < initial_heap_byte_size()) {
     vm_exit_during_initialization("Incompatible initial and maximum heap sizes specified");
   }
   if (PrintGCDetails && Verbose) {
     gclog_or_tty->print_cr("Minimum heap " SIZE_FORMAT "  Initial heap "
       SIZE_FORMAT "  Maximum heap " SIZE_FORMAT,
       min_heap_byte_size(), initial_heap_byte_size(), max_heap_byte_size());
   }
 }
 bool CollectorPolicy::use_should_clear_all_soft_refs(bool v) {
   bool result = _should_clear_all_soft_refs;
   set_should_clear_all_soft_refs(false);
   return result;
 }
 GenRemSet* CollectorPolicy::create_rem_set(MemRegion whole_heap,
                                            int max_covered_regions) {
   switch (rem_set_name()) {
   case GenRemSet::CardTable: {
     CardTableRS* res = new CardTableRS(whole_heap, max_covered_regions);
     return res;
   }
   default:
     guarantee(false, "unrecognized GenRemSet::Name");
     return NULL;
   }
 }
 void CollectorPolicy::cleared_all_soft_refs() {
   // If near gc overhear limit, continue to clear SoftRefs.  SoftRefs may
   // have been cleared in the last collection but if the gc overhear
   // limit continues to be near, SoftRefs should still be cleared.
   if (size_policy() != NULL) {
     _should_clear_all_soft_refs = size_policy()->gc_overhead_limit_near();
   }
   _all_soft_refs_clear = true;
 }
 // GenCollectorPolicy methods.
 size_t GenCollectorPolicy::scale_by_NewRatio_aligned(size_t base_size) {
   size_t x = base_size / (NewRatio+1);
   size_t new_gen_size = x > min_alignment() ?
                      align_size_down(x, min_alignment()) :
                      min_alignment();
   return new_gen_size;
 }
 size_t GenCollectorPolicy::bound_minus_alignment(size_t desired_size,
                                                  size_t maximum_size) {
   size_t alignment = min_alignment();
   size_t max_minus = maximum_size - alignment;
   return desired_size < max_minus ? desired_size : max_minus;
 }
 void GenCollectorPolicy::initialize_size_policy(size_t init_eden_size,
                                                 size_t init_promo_size,
                                                 size_t init_survivor_size) {
   const double max_gc_minor_pause_sec = ((double) MaxGCMinorPauseMillis)/1000.0;
   _size_policy = new AdaptiveSizePolicy(init_eden_size,
                                         init_promo_size,
                                         init_survivor_size,
                                         max_gc_minor_pause_sec,
                                         GCTimeRatio);
 }
 size_t GenCollectorPolicy::compute_max_alignment() {
   // The card marking array and the offset arrays for old generations are
   // committed in os pages as well. Make sure they are entirely full (to
   // avoid partial page problems), e.g. if 512 bytes heap corresponds to 1
   // byte entry and the os page size is 4096, the maximum heap size should
   // be 512*4096 = 2MB aligned.
   size_t alignment = GenRemSet::max_alignment_constraint(rem_set_name());
   // Parallel GC does its own alignment of the generations to avoid requiring a
   // large page (256M on some platforms) for the permanent generation.  The
   // other collectors should also be updated to do their own alignment and then
   // this use of lcm() should be removed.
   if (UseLargePages && !UseParallelGC) {
       // in presence of large pages we have to make sure that our
       // alignment is large page aware
       alignment = lcm(os::large_page_size(), alignment);
   }
   return alignment;
 }
 void GenCollectorPolicy::initialize_flags() {
   // All sizes must be multiples of the generation granularity.
   set_min_alignment((uintx) Generation::GenGrain);
   set_max_alignment(compute_max_alignment());
   assert(max_alignment() >= min_alignment() &&
          max_alignment() % min_alignment() == 0,
          "invalid alignment constraints");
   CollectorPolicy::initialize_flags();
   // All generational heaps have a youngest gen; handle those flags here.
   // Adjust max size parameters
   if (NewSize > MaxNewSize) {
     MaxNewSize = NewSize;
   }
   NewSize = align_size_down(NewSize, min_alignment());
   MaxNewSize = align_size_down(MaxNewSize, min_alignment());
   // Check validity of heap flags
   assert(NewSize     % min_alignment() == 0, "eden space alignment");
   assert(MaxNewSize  % min_alignment() == 0, "survivor space alignment");
   if (NewSize < 3*min_alignment()) {
      // make sure there room for eden and two survivor spaces
     vm_exit_during_initialization("Too small new size specified");
   }
   if (SurvivorRatio < 1 || NewRatio < 1) {
     vm_exit_during_initialization("Invalid heap ratio specified");
   }
 }
 void TwoGenerationCollectorPolicy::initialize_flags() {
   GenCollectorPolicy::initialize_flags();
   OldSize = align_size_down(OldSize, min_alignment());
   if (NewSize + OldSize > MaxHeapSize) {
     MaxHeapSize = NewSize + OldSize;
   }
   MaxHeapSize = align_size_up(MaxHeapSize, max_alignment());
   always_do_update_barrier = UseConcMarkSweepGC;
   // Check validity of heap flags
   assert(OldSize     % min_alignment() == 0, "old space alignment");
   assert(MaxHeapSize % max_alignment() == 0, "maximum heap alignment");
 }
 // Values set on the command line win over any ergonomically
 // set command line parameters.
 // Ergonomic choice of parameters are done before this
 // method is called.  Values for command line parameters such as NewSize
 // and MaxNewSize feed those ergonomic choices into this method.
 // This method makes the final generation sizings consistent with
 // themselves and with overall heap sizings.
 // In the absence of explicitly set command line flags, policies
 // such as the use of NewRatio are used to size the generation.
 void GenCollectorPolicy::initialize_size_info() {
   CollectorPolicy::initialize_size_info();
   // min_alignment() is used for alignment within a generation.
   // There is additional alignment done down stream for some
   // collectors that sometimes causes unwanted rounding up of
   // generations sizes.
   // Determine maximum size of gen0
   size_t max_new_size = 0;
   if (FLAG_IS_CMDLINE(MaxNewSize) || FLAG_IS_ERGO(MaxNewSize)) {
     if (MaxNewSize < min_alignment()) {
       max_new_size = min_alignment();
     }
     if (MaxNewSize >= max_heap_byte_size()) {
       max_new_size = align_size_down(max_heap_byte_size() - min_alignment(),
                                      min_alignment());
       warning("MaxNewSize (" SIZE_FORMAT "k) is equal to or "
         "greater than the entire heap (" SIZE_FORMAT "k).  A "
         "new generation size of " SIZE_FORMAT "k will be used.",
         MaxNewSize/K, max_heap_byte_size()/K, max_new_size/K);
     } else {
       max_new_size = align_size_down(MaxNewSize, min_alignment());
     }
   // The case for FLAG_IS_ERGO(MaxNewSize) could be treated
   // specially at this point to just use an ergonomically set
   // MaxNewSize to set max_new_size.  For cases with small
   // heaps such a policy often did not work because the MaxNewSize
   // was larger than the entire heap.  The interpretation given
   // to ergonomically set flags is that the flags are set
   // by different collectors for their own special needs but
   // are not allowed to badly shape the heap.  This allows the
   // different collectors to decide what's best for themselves
   // without having to factor in the overall heap shape.  It
   // can be the case in the future that the collectors would
   // only make "wise" ergonomics choices and this policy could
   // just accept those choices.  The choices currently made are
   // not always "wise".
   } else {
     max_new_size = scale_by_NewRatio_aligned(max_heap_byte_size());
     // Bound the maximum size by NewSize below (since it historically
     // would have been NewSize and because the NewRatio calculation could
     // yield a size that is too small) and bound it by MaxNewSize above.
     // Ergonomics plays here by previously calculating the desired
     // NewSize and MaxNewSize.
     max_new_size = MIN2(MAX2(max_new_size, NewSize), MaxNewSize);
   }
   assert(max_new_size > 0, "All paths should set max_new_size");
   // Given the maximum gen0 size, determine the initial and
   // minimum gen0 sizes.
   if (max_heap_byte_size() == min_heap_byte_size()) {
     // The maximum and minimum heap sizes are the same so
     // the generations minimum and initial must be the
     // same as its maximum.
     set_min_gen0_size(max_new_size);
     set_initial_gen0_size(max_new_size);
     set_max_gen0_size(max_new_size);
   } else {
     size_t desired_new_size = 0;
     if (!FLAG_IS_DEFAULT(NewSize)) {
       // If NewSize is set ergonomically (for example by cms), it
       // would make sense to use it.  If it is used, also use it
       // to set the initial size.  Although there is no reason
       // the minimum size and the initial size have to be the same,
       // the current implementation gets into trouble during the calculation
       // of the tenured generation sizes if they are different.
       // Note that this makes the initial size and the minimum size
       // generally small compared to the NewRatio calculation.
       _min_gen0_size = NewSize;
       desired_new_size = NewSize;
       max_new_size = MAX2(max_new_size, NewSize);
     } else {
       // For the case where NewSize is the default, use NewRatio
       // to size the minimum and initial generation sizes.
       // Use the default NewSize as the floor for these values.  If
       // NewRatio is overly large, the resulting sizes can be too
       // small.
       _min_gen0_size = MAX2(scale_by_NewRatio_aligned(min_heap_byte_size()),
                           NewSize);
       desired_new_size =
         MAX2(scale_by_NewRatio_aligned(initial_heap_byte_size()),
              NewSize);
     }
     assert(_min_gen0_size > 0, "Sanity check");
     set_initial_gen0_size(desired_new_size);
     set_max_gen0_size(max_new_size);
     // At this point the desirable initial and minimum sizes have been
     // determined without regard to the maximum sizes.
     // Bound the sizes by the corresponding overall heap sizes.
     set_min_gen0_size(
       bound_minus_alignment(_min_gen0_size, min_heap_byte_size()));
     set_initial_gen0_size(
       bound_minus_alignment(_initial_gen0_size, initial_heap_byte_size()));
     set_max_gen0_size(
       bound_minus_alignment(_max_gen0_size, max_heap_byte_size()));
     // At this point all three sizes have been checked against the
     // maximum sizes but have not been checked for consistency
     // among the three.
     // Final check min <= initial <= max
     set_min_gen0_size(MIN2(_min_gen0_size, _max_gen0_size));
     set_initial_gen0_size(
       MAX2(MIN2(_initial_gen0_size, _max_gen0_size), _min_gen0_size));
     set_min_gen0_size(MIN2(_min_gen0_size, _initial_gen0_size));
   }
   if (PrintGCDetails && Verbose) {
     gclog_or_tty->print_cr("1: Minimum gen0 " SIZE_FORMAT "  Initial gen0 "
       SIZE_FORMAT "  Maximum gen0 " SIZE_FORMAT,
       min_gen0_size(), initial_gen0_size(), max_gen0_size());
   }
 }
 // Call this method during the sizing of the gen1 to make
 // adjustments to gen0 because of gen1 sizing policy.  gen0 initially has
 // the most freedom in sizing because it is done before the
 // policy for gen1 is applied.  Once gen1 policies have been applied,
 // there may be conflicts in the shape of the heap and this method
 // is used to make the needed adjustments.  The application of the
 // policies could be more sophisticated (iterative for example) but
 // keeping it simple also seems a worthwhile goal.
 bool TwoGenerationCollectorPolicy::adjust_gen0_sizes(size_t* gen0_size_ptr,
                                                      size_t* gen1_size_ptr,
                                                      size_t heap_size,
                                                      size_t min_gen0_size) {
   bool result = false;
   if ((*gen1_size_ptr + *gen0_size_ptr) > heap_size) {
     if (((*gen0_size_ptr + OldSize) > heap_size) &&
        (heap_size - min_gen0_size) >= min_alignment()) {
       // Adjust gen0 down to accomodate OldSize
       *gen0_size_ptr = heap_size - min_gen0_size;
       *gen0_size_ptr =
         MAX2((uintx)align_size_down(*gen0_size_ptr, min_alignment()),
              min_alignment());
       assert(*gen0_size_ptr > 0, "Min gen0 is too large");
       result = true;
     } else {
       *gen1_size_ptr = heap_size - *gen0_size_ptr;
       *gen1_size_ptr =
         MAX2((uintx)align_size_down(*gen1_size_ptr, min_alignment()),
                        min_alignment());
     }
   }
   return result;
 }
 // Minimum sizes of the generations may be different than
 // the initial sizes.  An inconsistently is permitted here
 // in the total size that can be specified explicitly by
 // command line specification of OldSize and NewSize and
 // also a command line specification of -Xms.  Issue a warning
 // but allow the values to pass.
 void TwoGenerationCollectorPolicy::initialize_size_info() {
   GenCollectorPolicy::initialize_size_info();
   // At this point the minimum, initial and maximum sizes
   // of the overall heap and of gen0 have been determined.
   // The maximum gen1 size can be determined from the maximum gen0
   // and maximum heap size since no explicit flags exits
   // for setting the gen1 maximum.
   _max_gen1_size = max_heap_byte_size() - _max_gen0_size;
   _max_gen1_size =
     MAX2((uintx)align_size_down(_max_gen1_size, min_alignment()),
          min_alignment());
   // If no explicit command line flag has been set for the
   // gen1 size, use what is left for gen1.
   if (FLAG_IS_DEFAULT(OldSize) || FLAG_IS_ERGO(OldSize)) {
     // The user has not specified any value or ergonomics
     // has chosen a value (which may or may not be consistent
     // with the overall heap size).  In either case make
     // the minimum, maximum and initial sizes consistent
     // with the gen0 sizes and the overall heap sizes.
     assert(min_heap_byte_size() > _min_gen0_size,
       "gen0 has an unexpected minimum size");
     set_min_gen1_size(min_heap_byte_size() - min_gen0_size());
     set_min_gen1_size(
       MAX2((uintx)align_size_down(_min_gen1_size, min_alignment()),
            min_alignment()));
     set_initial_gen1_size(initial_heap_byte_size() - initial_gen0_size());
     set_initial_gen1_size(
       MAX2((uintx)align_size_down(_initial_gen1_size, min_alignment()),
            min_alignment()));
   } else {
     // It's been explicitly set on the command line.  Use the
     // OldSize and then determine the consequences.
     set_min_gen1_size(OldSize);
     set_initial_gen1_size(OldSize);
     // If the user has explicitly set an OldSize that is inconsistent
     // with other command line flags, issue a warning.
     // The generation minimums and the overall heap mimimum should
     // be within one heap alignment.
     if ((_min_gen1_size + _min_gen0_size + min_alignment()) <
            min_heap_byte_size()) {
       warning("Inconsistency between minimum heap size and minimum "
           "generation sizes: using minimum heap = " SIZE_FORMAT,
           min_heap_byte_size());
     }
     if ((OldSize > _max_gen1_size)) {
       warning("Inconsistency between maximum heap size and maximum "
           "generation sizes: using maximum heap = " SIZE_FORMAT
           " -XX:OldSize flag is being ignored",
           max_heap_byte_size());
     }
     // If there is an inconsistency between the OldSize and the minimum and/or
     // initial size of gen0, since OldSize was explicitly set, OldSize wins.
     if (adjust_gen0_sizes(&_min_gen0_size, &_min_gen1_size,
                           min_heap_byte_size(), OldSize)) {
       if (PrintGCDetails && Verbose) {
         gclog_or_tty->print_cr("2: Minimum gen0 " SIZE_FORMAT "  Initial gen0 "
               SIZE_FORMAT "  Maximum gen0 " SIZE_FORMAT,
               min_gen0_size(), initial_gen0_size(), max_gen0_size());
       }
     }
     // Initial size
     if (adjust_gen0_sizes(&_initial_gen0_size, &_initial_gen1_size,
                          initial_heap_byte_size(), OldSize)) {
       if (PrintGCDetails && Verbose) {
         gclog_or_tty->print_cr("3: Minimum gen0 " SIZE_FORMAT "  Initial gen0 "
           SIZE_FORMAT "  Maximum gen0 " SIZE_FORMAT,
           min_gen0_size(), initial_gen0_size(), max_gen0_size());
       }
     }
   }
   // Enforce the maximum gen1 size.
   set_min_gen1_size(MIN2(_min_gen1_size, _max_gen1_size));
   // Check that min gen1 <= initial gen1 <= max gen1
   set_initial_gen1_size(MAX2(_initial_gen1_size, _min_gen1_size));
   set_initial_gen1_size(MIN2(_initial_gen1_size, _max_gen1_size));
   if (PrintGCDetails && Verbose) {
     gclog_or_tty->print_cr("Minimum gen1 " SIZE_FORMAT "  Initial gen1 "
       SIZE_FORMAT "  Maximum gen1 " SIZE_FORMAT,
       min_gen1_size(), initial_gen1_size(), max_gen1_size());
   }
 }
 HeapWord* GenCollectorPolicy::mem_allocate_work(size_t size,
                                         bool is_tlab,
                                         bool* gc_overhead_limit_was_exceeded) {
   GenCollectedHeap *gch = GenCollectedHeap::heap();
   debug_only(gch->check_for_valid_allocation_state());
   assert(gch->no_gc_in_progress(), "Allocation during gc not allowed");
   // In general gc_overhead_limit_was_exceeded should be false so
   // set it so here and reset it to true only if the gc time
   // limit is being exceeded as checked below.
   *gc_overhead_limit_was_exceeded = false;
   HeapWord* result = NULL;
   // Loop until the allocation is satisified,
   // or unsatisfied after GC.
   for (int try_count = 1; /* return or throw */; try_count += 1) {
     HandleMark hm; // discard any handles allocated in each iteration
     // First allocation attempt is lock-free.
     Generation *gen0 = gch->get_gen(0);
     assert(gen0->supports_inline_contig_alloc(),
       "Otherwise, must do alloc within heap lock");
     if (gen0->should_allocate(size, is_tlab)) {
       result = gen0->par_allocate(size, is_tlab);
       if (result != NULL) {
         assert(gch->is_in_reserved(result), "result not in heap");
         return result;
       }
     }
     unsigned int gc_count_before;  // read inside the Heap_lock locked region
     {
       MutexLocker ml(Heap_lock);
       if (PrintGC && Verbose) {
         gclog_or_tty->print_cr("TwoGenerationCollectorPolicy::mem_allocate_work:"
                       " attempting locked slow path allocation");
       }
       // Note that only large objects get a shot at being
       // allocated in later generations.
       bool first_only = ! should_try_older_generation_allocation(size);
       result = gch->attempt_allocation(size, is_tlab, first_only);
       if (result != NULL) {
         assert(gch->is_in_reserved(result), "result not in heap");
         return result;
       }
       if (GC_locker::is_active_and_needs_gc()) {
         if (is_tlab) {
           return NULL;  // Caller will retry allocating individual object
         }
         if (!gch->is_maximal_no_gc()) {
           // Try and expand heap to satisfy request
           result = expand_heap_and_allocate(size, is_tlab);
           // result could be null if we are out of space
           if (result != NULL) {
             return result;
           }
         }
         // If this thread is not in a jni critical section, we stall
         // the requestor until the critical section has cleared and
         // GC allowed. When the critical section clears, a GC is
         // initiated by the last thread exiting the critical section; so
         // we retry the allocation sequence from the beginning of the loop,
         // rather than causing more, now probably unnecessary, GC attempts.
         JavaThread* jthr = JavaThread::current();
         if (!jthr->in_critical()) {
           MutexUnlocker mul(Heap_lock);
           // Wait for JNI critical section to be exited
           GC_locker::stall_until_clear();
           continue;
         } else {
           if (CheckJNICalls) {
             fatal("Possible deadlock due to allocating while"
                   " in jni critical section");
           }
           return NULL;
         }
       }
       // Read the gc count while the heap lock is held.
       gc_count_before = Universe::heap()->total_collections();
     }
     VM_GenCollectForAllocation op(size,
                                   is_tlab,
                                   gc_count_before);
     VMThread::execute(&op);
     if (op.prologue_succeeded()) {
       result = op.result();
       if (op.gc_locked()) {
          assert(result == NULL, "must be NULL if gc_locked() is true");
          continue;  // retry and/or stall as necessary
       }
       // Allocation has failed and a collection
       // has been done.  If the gc time limit was exceeded the
       // this time, return NULL so that an out-of-memory
       // will be thrown.  Clear gc_overhead_limit_exceeded
       // so that the overhead exceeded does not persist.
       const bool limit_exceeded = size_policy()->gc_overhead_limit_exceeded();
       const bool softrefs_clear = all_soft_refs_clear();
       assert(!limit_exceeded || softrefs_clear, "Should have been cleared");
       if (limit_exceeded && softrefs_clear) {
         *gc_overhead_limit_was_exceeded = true;
         size_policy()->set_gc_overhead_limit_exceeded(false);
         if (op.result() != NULL) {
           CollectedHeap::fill_with_object(op.result(), size);
         }
         return NULL;
       }
       assert(result == NULL || gch->is_in_reserved(result),
              "result not in heap");
       return result;
     }
     // Give a warning if we seem to be looping forever.
     if ((QueuedAllocationWarningCount > 0) &&
         (try_count % QueuedAllocationWarningCount == 0)) {
           warning("TwoGenerationCollectorPolicy::mem_allocate_work retries %d times \n\t"
                   " size=%d %s", try_count, size, is_tlab ? "(TLAB)" : "");
     }
   }
 }
 HeapWord* GenCollectorPolicy::expand_heap_and_allocate(size_t size,
                                                        bool   is_tlab) {
   GenCollectedHeap *gch = GenCollectedHeap::heap();
   HeapWord* result = NULL;
   for (int i = number_of_generations() - 1; i >= 0 && result == NULL; i--) {
     Generation *gen = gch->get_gen(i);
     if (gen->should_allocate(size, is_tlab)) {
       result = gen->expand_and_allocate(size, is_tlab);
     }
   }
   assert(result == NULL || gch->is_in_reserved(result), "result not in heap");
   return result;
 }
 HeapWord* GenCollectorPolicy::satisfy_failed_allocation(size_t size,
                                                         bool   is_tlab) {
   GenCollectedHeap *gch = GenCollectedHeap::heap();
   GCCauseSetter x(gch, GCCause::_allocation_failure);
   HeapWord* result = NULL;
   assert(size != 0, "Precondition violated");
   if (GC_locker::is_active_and_needs_gc()) {
     // GC locker is active; instead of a collection we will attempt
     // to expand the heap, if there's room for expansion.
     if (!gch->is_maximal_no_gc()) {
       result = expand_heap_and_allocate(size, is_tlab);
     }
     return result;   // could be null if we are out of space
   } else if (!gch->incremental_collection_will_fail(false /* don't consult_young */)) {
     // Do an incremental collection.
     gch->do_collection(false            /* full */,
                        false            /* clear_all_soft_refs */,
                        size             /* size */,
                        is_tlab          /* is_tlab */,
                        number_of_generations() - 1 /* max_level */);
   } else {
     if (Verbose && PrintGCDetails) {
       gclog_or_tty->print(" :: Trying full because partial may fail :: ");
     }
     // Try a full collection; see delta for bug id 6266275
     // for the original code and why this has been simplified
     // with from-space allocation criteria modified and
     // such allocation moved out of the safepoint path.
     gch->do_collection(true             /* full */,
                        false            /* clear_all_soft_refs */,
                        size             /* size */,
                        is_tlab          /* is_tlab */,
                        number_of_generations() - 1 /* max_level */);
   }
   result = gch->attempt_allocation(size, is_tlab, false /*first_only*/);
   if (result != NULL) {
     assert(gch->is_in_reserved(result), "result not in heap");
     return result;
   }
   // OK, collection failed, try expansion.
   result = expand_heap_and_allocate(size, is_tlab);
   if (result != NULL) {
     return result;
   }
   // If we reach this point, we're really out of memory. Try every trick
   // we can to reclaim memory. Force collection of soft references. Force
   // a complete compaction of the heap. Any additional methods for finding
   // free memory should be here, especially if they are expensive. If this
   // attempt fails, an OOM exception will be thrown.
   {
     IntFlagSetting flag_change(MarkSweepAlwaysCompactCount, 1); // Make sure the heap is fully compacted
     gch->do_collection(true             /* full */,
                        true             /* clear_all_soft_refs */,
                        size             /* size */,
                        is_tlab          /* is_tlab */,
                        number_of_generations() - 1 /* max_level */);
   }
   result = gch->attempt_allocation(size, is_tlab, false /* first_only */);
   if (result != NULL) {
     assert(gch->is_in_reserved(result), "result not in heap");
     return result;
   }
   assert(!should_clear_all_soft_refs(),
     "Flag should have been handled and cleared prior to this point");
   // What else?  We might try synchronous finalization later.  If the total
   // space available is large enough for the allocation, then a more
   // complete compaction phase than we've tried so far might be
   // appropriate.
   return NULL;
 }
 MetaWord* CollectorPolicy::satisfy_failed_metadata_allocation(
                                                  ClassLoaderData* loader_data,
                                                  size_t word_size,
                                                  Metaspace::MetadataType mdtype) {
   uint loop_count = 0;
   uint gc_count = 0;
   uint full_gc_count = 0;
   assert(!Heap_lock->owned_by_self(), "Should not be holding the Heap_lock");
   do {
     MetaWord* result = NULL;
     if (GC_locker::is_active_and_needs_gc()) {
       // If the GC_locker is active, just expand and allocate.
       // If that does not succeed, wait if this thread is not
       // in a critical section itself.
       result =
         loader_data->metaspace_non_null()->expand_and_allocate(word_size,
                                                                mdtype);
       if (result != NULL) {
         return result;
       }
       JavaThread* jthr = JavaThread::current();
       if (!jthr->in_critical()) {
         // Wait for JNI critical section to be exited
         GC_locker::stall_until_clear();
         // The GC invoked by the last thread leaving the critical
         // section will be a young collection and a full collection
         // is (currently) needed for unloading classes so continue
         // to the next iteration to get a full GC.
         continue;
       } else {
         if (CheckJNICalls) {
           fatal("Possible deadlock due to allocating while"
                 " in jni critical section");
         }
         return NULL;
       }
     }
     {  // Need lock to get self consistent gc_count's
       MutexLocker ml(Heap_lock);
       gc_count      = Universe::heap()->total_collections();
       full_gc_count = Universe::heap()->total_full_collections();
     }
     // Generate a VM operation
     VM_CollectForMetadataAllocation op(loader_data,
                                        word_size,
                                        mdtype,
                                        gc_count,
                                        full_gc_count,
                                        GCCause::_metadata_GC_threshold);
     VMThread::execute(&op);
     // If GC was locked out, try again.  Check
     // before checking success because the prologue
     // could have succeeded and the GC still have
     // been locked out.
     if (op.gc_locked()) {
       continue;
     }
     if (op.prologue_succeeded()) {
       return op.result();
     }
     loop_count++;
     if ((QueuedAllocationWarningCount > 0) &&
         (loop_count % QueuedAllocationWarningCount == 0)) {
       warning("satisfy_failed_metadata_allocation() retries %d times \n\t"
               " size=%d", loop_count, word_size);
     }
   } while (true);  // Until a GC is done
 }
 // Return true if any of the following is true:
 // . the allocation won't fit into the current young gen heap
 // . gc locker is occupied (jni critical section)
 // . heap memory is tight -- the most recent previous collection
 //   was a full collection because a partial collection (would
 //   have) failed and is likely to fail again
 bool GenCollectorPolicy::should_try_older_generation_allocation(
         size_t word_size) const {
   GenCollectedHeap* gch = GenCollectedHeap::heap();
   size_t gen0_capacity = gch->get_gen(0)->capacity_before_gc();
   return    (word_size > heap_word_size(gen0_capacity))
          || GC_locker::is_active_and_needs_gc()
          || gch->incremental_collection_failed();
 }
 //
 // MarkSweepPolicy methods
 //
 MarkSweepPolicy::MarkSweepPolicy() {
   initialize_all();
 }
 void MarkSweepPolicy::initialize_generations() {
   _generations = new GenerationSpecPtr[number_of_generations()];
   if (_generations == NULL)
     vm_exit_during_initialization("Unable to allocate gen spec");
   if (UseParNewGC) {
     _generations[0] = new GenerationSpec(Generation::ParNew, _initial_gen0_size, _max_gen0_size);
   } else {
     _generations[0] = new GenerationSpec(Generation::DefNew, _initial_gen0_size, _max_gen0_size);
   }
   _generations[1] = new GenerationSpec(Generation::MarkSweepCompact, _initial_gen1_size, _max_gen1_size);
   if (_generations[0] == NULL || _generations[1] == NULL)
     vm_exit_during_initialization("Unable to allocate gen spec");
 }
 void MarkSweepPolicy::initialize_gc_policy_counters() {
   // initialize the policy counters - 2 collectors, 3 generations
   if (UseParNewGC) {
     _gc_policy_counters = new GCPolicyCounters("ParNew:MSC", 2, 3);
   } else {
     _gc_policy_counters = new GCPolicyCounters("Copy:MSC", 2, 3);
   }
 }

Mercurial > jdk8-mips64-public > hotspot / annotate

src/share/vm/memory/collectorPolicy.cpp@ca0a78017dc7 (annotated)

src/share/vm/memory/collectorPolicy.cpp