changeset 26701:f8ff74a6c058

8052172: Evacuation failure handling in G1 does not evacuate all objects if -XX:-G1DeferredRSUpdate is set Summary: Remove -XX:-G1DeferredRSUpdate functionality as it is racy. During evacuation failure handling, threads where evacuation failure handling occurred may try to add remembered sets to regions which remembered sets are currently being scanned. The iterator to handle the remembered set scan does not support addition of entries during scan and so may skip valid references. Reviewed-by: iveresov, brutisso, mgerdin
author tschatzl
date Tue, 16 Sep 2014 10:28:15 +0200
parents 8107d0778244
children a5739f4f8eca
files hotspot/src/share/vm/gc_implementation/g1/g1CollectedHeap.cpp hotspot/src/share/vm/gc_implementation/g1/g1EvacFailure.hpp hotspot/src/share/vm/gc_implementation/g1/g1GCPhaseTimes.cpp hotspot/src/share/vm/gc_implementation/g1/g1ParScanThreadState.hpp hotspot/src/share/vm/gc_implementation/g1/g1ParScanThreadState.inline.hpp hotspot/src/share/vm/gc_implementation/g1/g1RemSet.cpp hotspot/src/share/vm/gc_implementation/g1/g1RemSet.hpp hotspot/src/share/vm/gc_implementation/g1/g1RemSet.inline.hpp hotspot/src/share/vm/gc_implementation/g1/g1_globals.hpp hotspot/test/gc/g1/TestDeferredRSUpdate.java
diffstat 10 files changed, 41 insertions(+), 263 deletions(-) [+]
line wrap: on
line diff
--- a/hotspot/src/share/vm/gc_implementation/g1/g1CollectedHeap.cpp	Tue Jun 24 15:50:50 2014 +0200
+++ b/hotspot/src/share/vm/gc_implementation/g1/g1CollectedHeap.cpp	Tue Sep 16 10:28:15 2014 +0200
@@ -1481,9 +1481,7 @@
 
       // Discard all rset updates
       JavaThread::dirty_card_queue_set().abandon_logs();
-      assert(!G1DeferredRSUpdate
-             || (G1DeferredRSUpdate &&
-                (dirty_card_queue_set().completed_buffers_num() == 0)), "Should not be any");
+      assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty");
 
       _young_list->reset_sampled_info();
       // At this point there should be no regions in the
@@ -2094,15 +2092,13 @@
                                                 concurrent_g1_refine()->red_zone(),
                                                 Shared_DirtyCardQ_lock);
 
-  if (G1DeferredRSUpdate) {
-    dirty_card_queue_set().initialize(NULL, // Should never be called by the Java code
-                                      DirtyCardQ_CBL_mon,
-                                      DirtyCardQ_FL_lock,
-                                      -1, // never trigger processing
-                                      -1, // no limit on length
-                                      Shared_DirtyCardQ_lock,
-                                      &JavaThread::dirty_card_queue_set());
-  }
+  dirty_card_queue_set().initialize(NULL, // Should never be called by the Java code
+                                    DirtyCardQ_CBL_mon,
+                                    DirtyCardQ_FL_lock,
+                                    -1, // never trigger processing
+                                    -1, // no limit on length
+                                    Shared_DirtyCardQ_lock,
+                                    &JavaThread::dirty_card_queue_set());
 
   // Initialize the card queue set used to hold cards containing
   // references into the collection set.
@@ -5389,7 +5385,6 @@
 };
 
 void G1CollectedHeap::redirty_logged_cards() {
-  guarantee(G1DeferredRSUpdate, "Must only be called when using deferred RS updates.");
   double redirty_logged_cards_start = os::elapsedTime();
 
   uint n_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
@@ -6049,9 +6044,7 @@
   // RSets.
   enqueue_discovered_references(n_workers);
 
-  if (G1DeferredRSUpdate) {
-    redirty_logged_cards();
-  }
+  redirty_logged_cards();
   COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
 }
 
--- a/hotspot/src/share/vm/gc_implementation/g1/g1EvacFailure.hpp	Tue Jun 24 15:50:50 2014 +0200
+++ b/hotspot/src/share/vm/gc_implementation/g1/g1EvacFailure.hpp	Tue Sep 16 10:28:15 2014 +0200
@@ -176,15 +176,17 @@
 class RemoveSelfForwardPtrHRClosure: public HeapRegionClosure {
   G1CollectedHeap* _g1h;
   ConcurrentMark* _cm;
-  OopsInHeapRegionClosure *_update_rset_cl;
   uint _worker_id;
 
+  DirtyCardQueue _dcq;
+  UpdateRSetDeferred _update_rset_cl;
+
 public:
   RemoveSelfForwardPtrHRClosure(G1CollectedHeap* g1h,
-                                OopsInHeapRegionClosure* update_rset_cl,
                                 uint worker_id) :
-    _g1h(g1h), _update_rset_cl(update_rset_cl),
-    _worker_id(worker_id), _cm(_g1h->concurrent_mark()) { }
+    _g1h(g1h), _dcq(&g1h->dirty_card_queue_set()), _update_rset_cl(g1h, &_dcq),
+    _worker_id(worker_id), _cm(_g1h->concurrent_mark()) {
+    }
 
   bool doHeapRegion(HeapRegion *hr) {
     bool during_initial_mark = _g1h->g1_policy()->during_initial_mark_pause();
@@ -195,7 +197,7 @@
 
     if (hr->claimHeapRegion(HeapRegion::ParEvacFailureClaimValue)) {
       if (hr->evacuation_failed()) {
-        RemoveSelfForwardPtrObjClosure rspc(_g1h, _cm, hr, _update_rset_cl,
+        RemoveSelfForwardPtrObjClosure rspc(_g1h, _cm, hr, &_update_rset_cl,
                                             during_initial_mark,
                                             during_conc_mark,
                                             _worker_id);
@@ -214,7 +216,7 @@
         // whenever this might be required in the future.
         hr->rem_set()->reset_for_par_iteration();
         hr->reset_bot();
-        _update_rset_cl->set_region(hr);
+        _update_rset_cl.set_region(hr);
         hr->object_iterate(&rspc);
 
         hr->rem_set()->clean_strong_code_roots(hr);
@@ -238,16 +240,7 @@
     _g1h(g1h) { }
 
   void work(uint worker_id) {
-    UpdateRSetImmediate immediate_update(_g1h->g1_rem_set());
-    DirtyCardQueue dcq(&_g1h->dirty_card_queue_set());
-    UpdateRSetDeferred deferred_update(_g1h, &dcq);
-
-    OopsInHeapRegionClosure *update_rset_cl = &deferred_update;
-    if (!G1DeferredRSUpdate) {
-      update_rset_cl = &immediate_update;
-    }
-
-    RemoveSelfForwardPtrHRClosure rsfp_cl(_g1h, update_rset_cl, worker_id);
+    RemoveSelfForwardPtrHRClosure rsfp_cl(_g1h, worker_id);
 
     HeapRegion* hr = _g1h->start_cset_region_for_worker(worker_id);
     _g1h->collection_set_iterate_from(hr, &rsfp_cl);
--- a/hotspot/src/share/vm/gc_implementation/g1/g1GCPhaseTimes.cpp	Tue Jun 24 15:50:50 2014 +0200
+++ b/hotspot/src/share/vm/gc_implementation/g1/g1GCPhaseTimes.cpp	Tue Sep 16 10:28:15 2014 +0200
@@ -237,10 +237,8 @@
   _last_gc_worker_times_ms.verify();
   _last_gc_worker_other_times_ms.verify();
 
-  if (G1DeferredRSUpdate) {
-    _last_redirty_logged_cards_time_ms.verify();
-    _last_redirty_logged_cards_processed_cards.verify();
-  }
+  _last_redirty_logged_cards_time_ms.verify();
+  _last_redirty_logged_cards_processed_cards.verify();
 }
 
 void G1GCPhaseTimes::note_string_dedup_fixup_start() {
@@ -352,12 +350,10 @@
     _recorded_non_young_cset_choice_time_ms));
   print_stats(2, "Ref Proc", _cur_ref_proc_time_ms);
   print_stats(2, "Ref Enq", _cur_ref_enq_time_ms);
-  if (G1DeferredRSUpdate) {
-    print_stats(2, "Redirty Cards", _recorded_redirty_logged_cards_time_ms);
-    if (G1Log::finest()) {
-      _last_redirty_logged_cards_time_ms.print(3, "Parallel Redirty");
-      _last_redirty_logged_cards_processed_cards.print(3, "Redirtied Cards");
-    }
+  print_stats(2, "Redirty Cards", _recorded_redirty_logged_cards_time_ms);
+  if (G1Log::finest()) {
+    _last_redirty_logged_cards_time_ms.print(3, "Parallel Redirty");
+    _last_redirty_logged_cards_processed_cards.print(3, "Redirtied Cards");
   }
   if (G1ReclaimDeadHumongousObjectsAtYoungGC) {
     print_stats(2, "Humongous Reclaim", _cur_fast_reclaim_humongous_time_ms);
--- a/hotspot/src/share/vm/gc_implementation/g1/g1ParScanThreadState.hpp	Tue Jun 24 15:50:50 2014 +0200
+++ b/hotspot/src/share/vm/gc_implementation/g1/g1ParScanThreadState.hpp	Tue Sep 16 10:28:15 2014 +0200
@@ -84,20 +84,6 @@
   DirtyCardQueue& dirty_card_queue()             { return _dcq;  }
   G1SATBCardTableModRefBS* ctbs()                { return _ct_bs; }
 
-  template <class T> inline void immediate_rs_update(HeapRegion* from, T* p, int tid);
-
-  template <class T> void deferred_rs_update(HeapRegion* from, T* p, int tid) {
-    // If the new value of the field points to the same region or
-    // is the to-space, we don't need to include it in the Rset updates.
-    if (!from->is_in_reserved(oopDesc::load_decode_heap_oop(p)) && !from->is_survivor()) {
-      size_t card_index = ctbs()->index_for(p);
-      // If the card hasn't been added to the buffer, do it.
-      if (ctbs()->mark_card_deferred(card_index)) {
-        dirty_card_queue().enqueue((jbyte*)ctbs()->byte_for_index(card_index));
-      }
-    }
-  }
-
  public:
   G1ParScanThreadState(G1CollectedHeap* g1h, uint queue_num, ReferenceProcessor* rp);
   ~G1ParScanThreadState();
@@ -124,8 +110,17 @@
     _refs->push(ref);
   }
 
-  template <class T> inline void update_rs(HeapRegion* from, T* p, int tid);
-
+  template <class T> void update_rs(HeapRegion* from, T* p, int tid) {
+    // If the new value of the field points to the same region or
+    // is the to-space, we don't need to include it in the Rset updates.
+    if (!from->is_in_reserved(oopDesc::load_decode_heap_oop(p)) && !from->is_survivor()) {
+      size_t card_index = ctbs()->index_for(p);
+      // If the card hasn't been added to the buffer, do it.
+      if (ctbs()->mark_card_deferred(card_index)) {
+        dirty_card_queue().enqueue((jbyte*)ctbs()->byte_for_index(card_index));
+      }
+    }
+  }
  private:
 
   inline HeapWord* allocate(GCAllocPurpose purpose, size_t word_sz);
--- a/hotspot/src/share/vm/gc_implementation/g1/g1ParScanThreadState.inline.hpp	Tue Jun 24 15:50:50 2014 +0200
+++ b/hotspot/src/share/vm/gc_implementation/g1/g1ParScanThreadState.inline.hpp	Tue Sep 16 10:28:15 2014 +0200
@@ -29,20 +29,6 @@
 #include "gc_implementation/g1/g1RemSet.inline.hpp"
 #include "oops/oop.inline.hpp"
 
-template <class T> inline void G1ParScanThreadState::immediate_rs_update(HeapRegion* from, T* p, int tid) {
-  if (!from->is_survivor()) {
-    _g1_rem->par_write_ref(from, p, tid);
-  }
-}
-
-template <class T> void G1ParScanThreadState::update_rs(HeapRegion* from, T* p, int tid) {
-  if (G1DeferredRSUpdate) {
-    deferred_rs_update(from, p, tid);
-  } else {
-    immediate_rs_update(from, p, tid);
-  }
-}
-
 template <class T> void G1ParScanThreadState::do_oop_evac(T* p, HeapRegion* from) {
   assert(!oopDesc::is_null(oopDesc::load_decode_heap_oop(p)),
          "Reference should not be NULL here as such are never pushed to the task queue.");
--- a/hotspot/src/share/vm/gc_implementation/g1/g1RemSet.cpp	Tue Jun 24 15:50:50 2014 +0200
+++ b/hotspot/src/share/vm/gc_implementation/g1/g1RemSet.cpp	Tue Sep 16 10:28:15 2014 +0200
@@ -339,12 +339,8 @@
   // are just discarded (there's no need to update the RSets of regions
   // that were in the collection set - after the pause these regions
   // are wholly 'free' of live objects. In the event of an evacuation
-  // failure the cards/buffers in this queue set are:
-  // * passed to the DirtyCardQueueSet that is used to manage deferred
-  //   RSet updates, or
-  // * scanned for references that point into the collection set
-  //   and the RSet of the corresponding region in the collection set
-  //   is updated immediately.
+  // failure the cards/buffers in this queue set are passed to the
+  // DirtyCardQueueSet that is used to manage RSet updates
   DirtyCardQueue into_cset_dcq(&_g1->into_cset_dirty_card_queue_set());
 
   assert((ParallelGCThreads > 0) || worker_i == 0, "invariant");
@@ -358,7 +354,6 @@
 
 void G1RemSet::prepare_for_oops_into_collection_set_do() {
   cleanupHRRS();
-  ConcurrentG1Refine* cg1r = _g1->concurrent_g1_refine();
   _g1->set_refine_cte_cl_concurrency(false);
   DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
   dcqs.concatenate_logs();
@@ -371,66 +366,6 @@
   _total_cards_scanned = 0;
 }
 
-
-// This closure, applied to a DirtyCardQueueSet, is used to immediately
-// update the RSets for the regions in the CSet. For each card it iterates
-// through the oops which coincide with that card. It scans the reference
-// fields in each oop; when it finds an oop that points into the collection
-// set, the RSet for the region containing the referenced object is updated.
-class UpdateRSetCardTableEntryIntoCSetClosure: public CardTableEntryClosure {
-  G1CollectedHeap* _g1;
-  CardTableModRefBS* _ct_bs;
-public:
-  UpdateRSetCardTableEntryIntoCSetClosure(G1CollectedHeap* g1,
-                                          CardTableModRefBS* bs):
-    _g1(g1), _ct_bs(bs)
-  { }
-
-  bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
-    // Construct the region representing the card.
-    HeapWord* start = _ct_bs->addr_for(card_ptr);
-    // And find the region containing it.
-    HeapRegion* r = _g1->heap_region_containing(start);
-
-    // Scan oops in the card looking for references into the collection set
-    // Don't use addr_for(card_ptr + 1) which can ask for
-    // a card beyond the heap.  This is not safe without a perm
-    // gen.
-    HeapWord* end   = start + CardTableModRefBS::card_size_in_words;
-    MemRegion scanRegion(start, end);
-
-    UpdateRSetImmediate update_rs_cl(_g1->g1_rem_set());
-    FilterIntoCSClosure update_rs_cset_oop_cl(NULL, _g1, &update_rs_cl);
-    FilterOutOfRegionClosure filter_then_update_rs_cset_oop_cl(r, &update_rs_cset_oop_cl);
-
-    // We can pass false as the "filter_young" parameter here as:
-    // * we should be in a STW pause,
-    // * the DCQS to which this closure is applied is used to hold
-    //   references that point into the collection set from the prior
-    //   RSet updating,
-    // * the post-write barrier shouldn't be logging updates to young
-    //   regions (but there is a situation where this can happen - see
-    //   the comment in G1RemSet::refine_card() below -
-    //   that should not be applicable here), and
-    // * during actual RSet updating, the filtering of cards in young
-    //   regions in HeapRegion::oops_on_card_seq_iterate_careful is
-    //   employed.
-    // As a result, when this closure is applied to "refs into cset"
-    // DCQS, we shouldn't see any cards in young regions.
-    update_rs_cl.set_region(r);
-    HeapWord* stop_point =
-      r->oops_on_card_seq_iterate_careful(scanRegion,
-                                          &filter_then_update_rs_cset_oop_cl,
-                                          false /* filter_young */,
-                                          NULL  /* card_ptr */);
-
-    // Since this is performed in the event of an evacuation failure, we
-    // we shouldn't see a non-null stop point
-    assert(stop_point == NULL, "saw an unallocated region");
-    return true;
-  }
-};
-
 void G1RemSet::cleanup_after_oops_into_collection_set_do() {
   guarantee( _cards_scanned != NULL, "invariant" );
   _total_cards_scanned = 0;
@@ -451,25 +386,10 @@
     double restore_remembered_set_start = os::elapsedTime();
 
     // Restore remembered sets for the regions pointing into the collection set.
-    if (G1DeferredRSUpdate) {
-      // If deferred RS updates are enabled then we just need to transfer
-      // the completed buffers from (a) the DirtyCardQueueSet used to hold
-      // cards that contain references that point into the collection set
-      // to (b) the DCQS used to hold the deferred RS updates
-      _g1->dirty_card_queue_set().merge_bufferlists(&into_cset_dcqs);
-    } else {
-
-      CardTableModRefBS* bs = (CardTableModRefBS*)_g1->barrier_set();
-      UpdateRSetCardTableEntryIntoCSetClosure update_rs_cset_immediate(_g1, bs);
-
-      int n_completed_buffers = 0;
-      while (into_cset_dcqs.apply_closure_to_completed_buffer(&update_rs_cset_immediate,
-                                                    0, 0, true)) {
-        n_completed_buffers++;
-      }
-      assert(n_completed_buffers == into_cset_n_buffers, "missed some buffers");
-    }
-
+    // We just need to transfer the completed buffers from the DirtyCardQueueSet
+    // used to hold cards that contain references that point into the collection set
+    // to the DCQS used to hold the deferred RS updates.
+    _g1->dirty_card_queue_set().merge_bufferlists(&into_cset_dcqs);
     _g1->g1_policy()->phase_times()->record_evac_fail_restore_remsets((os::elapsedTime() - restore_remembered_set_start) * 1000.0);
   }
 
--- a/hotspot/src/share/vm/gc_implementation/g1/g1RemSet.hpp	Tue Jun 24 15:50:50 2014 +0200
+++ b/hotspot/src/share/vm/gc_implementation/g1/g1RemSet.hpp	Tue Sep 16 10:28:15 2014 +0200
@@ -193,18 +193,4 @@
   bool apply_to_weak_ref_discovered_field() { return true; }
 };
 
-class UpdateRSetImmediate: public OopsInHeapRegionClosure {
-private:
-  G1RemSet* _g1_rem_set;
-
-  template <class T> void do_oop_work(T* p);
-public:
-  UpdateRSetImmediate(G1RemSet* rs) :
-    _g1_rem_set(rs) {}
-
-  virtual void do_oop(narrowOop* p) { do_oop_work(p); }
-  virtual void do_oop(      oop* p) { do_oop_work(p); }
-};
-
-
 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_G1REMSET_HPP
--- a/hotspot/src/share/vm/gc_implementation/g1/g1RemSet.inline.hpp	Tue Jun 24 15:50:50 2014 +0200
+++ b/hotspot/src/share/vm/gc_implementation/g1/g1RemSet.inline.hpp	Tue Sep 16 10:28:15 2014 +0200
@@ -79,13 +79,4 @@
   _rs->par_write_ref(_from, p, _worker_i);
 }
 
-template <class T>
-inline void UpdateRSetImmediate::do_oop_work(T* p) {
-  assert(_from->is_in_reserved(p), "paranoia");
-  T heap_oop = oopDesc::load_heap_oop(p);
-  if (!oopDesc::is_null(heap_oop) && !_from->is_survivor()) {
-    _g1_rem_set->par_write_ref(_from, p, 0);
-  }
-}
-
 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_G1REMSET_INLINE_HPP
--- a/hotspot/src/share/vm/gc_implementation/g1/g1_globals.hpp	Tue Jun 24 15:50:50 2014 +0200
+++ b/hotspot/src/share/vm/gc_implementation/g1/g1_globals.hpp	Tue Sep 16 10:28:15 2014 +0200
@@ -108,9 +108,6 @@
   develop(bool, G1RSBarrierRegionFilter, true,                              \
           "If true, generate region filtering code in RS barrier")          \
                                                                             \
-  develop(bool, G1DeferredRSUpdate, true,                                   \
-          "If true, use deferred RS updates")                               \
-                                                                            \
   develop(bool, G1RSLogCheckCardTable, false,                               \
           "If true, verify that no dirty cards remain after RS log "        \
           "processing.")                                                    \
--- a/hotspot/test/gc/g1/TestDeferredRSUpdate.java	Tue Jun 24 15:50:50 2014 +0200
+++ /dev/null	Thu Jan 01 00:00:00 1970 +0000
@@ -1,79 +0,0 @@
-/*
- * Copyright (c) 2014, 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.
- */
-
-/*
- * @test TestDeferredRSUpdate
- * @bug 8040977 8052170
- * @summary Ensure that running with -XX:-G1DeferredRSUpdate does not crash the VM
- * @key gc
- * @library /testlibrary
- */
-
-import com.oracle.java.testlibrary.ProcessTools;
-import com.oracle.java.testlibrary.OutputAnalyzer;
-
-public class TestDeferredRSUpdate {
-  public static void main(String[] args) throws Exception {
-    GCTest.main(args);
-
-    ProcessBuilder pb = ProcessTools.createJavaProcessBuilder("-XX:+UseG1GC",
-                                                              "-Xmx10M",
-                                                              "-XX:+PrintGCDetails",
-                                                              // G1DeferredRSUpdate is a develop option, but we cannot limit execution of this test to only debug VMs.
-                                                              "-XX:+IgnoreUnrecognizedVMOptions",
-                                                              "-XX:-G1DeferredRSUpdate",
-                                                              GCTest.class.getName());
-
-    OutputAnalyzer output = new OutputAnalyzer(pb.start());
-    output.shouldHaveExitValue(0);
-  }
-
-  static class GCTest {
-    private static Object[] garbage = new Object[32];
-
-    public static void main(String [] args) {
-      System.out.println("Creating garbage");
-      // Create 128MB of garbage. This should result in at least one minor GC, with
-      // some objects copied to old gen. As references from old to young are installed,
-      // the crash due to the use before initialize occurs.
-      Object prev = null;
-      Object prevPrev = null;
-      for (int i = 0; i < 1024; i++) {
-        Object[] next = new Object[32 * 1024];
-        next[0] = prev;
-        next[1] = prevPrev;
-
-        Object[] cur = (Object[]) garbage[i % garbage.length];
-        if (cur != null) {
-          cur[0] = null;
-          cur[1] = null;
-        }
-        garbage[i % garbage.length] = next;
-
-        prevPrev = prev;
-        prev = next;
-      }
-      System.out.println("Done");
-    }
-  }
-}