7041879: G1: introduce stress testing parameter to cause frequent evacuation failures

Summary: Add the flags G1EvacuationFailureALot flag (and supporting flags) to force trigger evacuation failures. The support flags control how often to trigger an evacuation failure and during which types of evacuation pause. This functionality is analogous to that of PromotionFailureALot for the other collectors.
Reviewed-by: brutisso

src/share/vm/gc_implementation/g1/g1CollectedHeap.cpp

@@ -1945,6 +1945,9 @@ G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) :
 
   clear_cset_start_regions();
 
+  // Initialize the G1EvacuationFailureALot counters and flags.
+  NOT_PRODUCT(reset_evacuation_should_fail();)
+
   guarantee(_task_queues != NULL, "task_queues allocation failure.");
 #ifdef SPARC
   // Issue a stern warning, but allow use for experimentation and debugging.
@@ -4564,7 +4567,15 @@ oop G1ParCopyClosure<do_gen_barrier, barrier, do_mark_object>
   GCAllocPurpose alloc_purpose = g1p->evacuation_destination(from_region, age,
                                                              word_sz);
   HeapWord* obj_ptr = _par_scan_state->allocate(alloc_purpose, word_sz);
-  oop       obj     = oop(obj_ptr);
+#ifndef PRODUCT
+  // Should this evacuation fail?
+  if (_g1->evacuation_should_fail()) {
+    if (obj_ptr != NULL) {
+      _par_scan_state->undo_allocation(alloc_purpose, obj_ptr, word_sz);
+      obj_ptr = NULL;
+    }
+  }
+#endif // !PRODUCT
 
   if (obj_ptr == NULL) {
     // This will either forward-to-self, or detect that someone else has
@@ -4573,6 +4584,8 @@ oop G1ParCopyClosure<do_gen_barrier, barrier, do_mark_object>
     return _g1->handle_evacuation_failure_par(cl, old);
   }
 
+  oop obj = oop(obj_ptr);
+
   // We're going to allocate linearly, so might as well prefetch ahead.
   Prefetch::write(obj_ptr, PrefetchCopyIntervalInBytes);
 
@@ -5578,6 +5591,9 @@ void G1CollectedHeap::evacuate_collection_set() {
   _expand_heap_after_alloc_failure = true;
   set_evacuation_failed(false);
 
+  // Should G1EvacuationFailureALot be in effect for this GC?
+  NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
+
   g1_rem_set()->prepare_for_oops_into_collection_set_do();
   concurrent_g1_refine()->set_use_cache(false);
   concurrent_g1_refine()->clear_hot_cache_claimed_index();
@@ -5669,6 +5685,11 @@ void G1CollectedHeap::evacuate_collection_set() {
 
   if (evacuation_failed()) {
     remove_self_forwarding_pointers();
+
+    // Reset the G1EvacuationFailureALot counters and flags
+    // Note: the values are reset only when an actual
+    // evacuation failure occurs.
+    NOT_PRODUCT(reset_evacuation_should_fail();)
   }
 
   // Enqueue any remaining references remaining on the STW

src/share/vm/gc_implementation/g1/g1CollectedHeap.hpp

@@ -915,6 +915,39 @@ protected:
   oop handle_evacuation_failure_par(OopsInHeapRegionClosure* cl, oop obj);
   void handle_evacuation_failure_common(oop obj, markOop m);
 
+#ifndef PRODUCT
+  // Support for forcing evacuation failures. Analogous to
+  // PromotionFailureALot for the other collectors.
+
+  // Records whether G1EvacuationFailureALot should be in effect
+  // for the current GC
+  bool _evacuation_failure_alot_for_current_gc;
+
+  // Used to record the GC number for interval checking when
+  // determining whether G1EvaucationFailureALot is in effect
+  // for the current GC.
+  size_t _evacuation_failure_alot_gc_number;
+
+  // Count of the number of evacuations between failures.
+  volatile size_t _evacuation_failure_alot_count;
+
+  // Set whether G1EvacuationFailureALot should be in effect
+  // for the current GC (based upon the type of GC and which
+  // command line flags are set);
+  inline bool evacuation_failure_alot_for_gc_type(bool gcs_are_young,
+                                                  bool during_initial_mark,
+                                                  bool during_marking);
+
+  inline void set_evacuation_failure_alot_for_current_gc();
+
+  // Return true if it's time to cause an evacuation failure.
+  inline bool evacuation_should_fail();
+
+  // Reset the G1EvacuationFailureALot counters.  Should be called at
+  // the end of an evacuation pause in which an evacuation failure ocurred.
+  inline void reset_evacuation_should_fail();
+#endif // !PRODUCT
+
   // ("Weak") Reference processing support.
   //
   // G1 has 2 instances of the referece processor class. One

src/share/vm/gc_implementation/g1/g1CollectedHeap.inline.hpp

 /*
- * Copyright (c) 2001, 2011, Oracle and/or its affiliates. All rights reserved.
+ * 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
@@ -138,7 +138,7 @@ inline RefToScanQueue* G1CollectedHeap::task_queue(int i) const {
   return _task_queues->queue(i);
 }
 
-inline  bool G1CollectedHeap::isMarkedPrev(oop obj) const {
+inline bool G1CollectedHeap::isMarkedPrev(oop obj) const {
   return _cm->prevMarkBitMap()->isMarked((HeapWord *)obj);
 }
 
@@ -146,4 +146,77 @@ inline bool G1CollectedHeap::isMarkedNext(oop obj) const {
   return _cm->nextMarkBitMap()->isMarked((HeapWord *)obj);
 }
 
+#ifndef PRODUCT
+// Support for G1EvacuationFailureALot
+
+inline bool
+G1CollectedHeap::evacuation_failure_alot_for_gc_type(bool gcs_are_young,
+                                                     bool during_initial_mark,
+                                                     bool during_marking) {
+  bool res = false;
+  if (during_marking) {
+    res |= G1EvacuationFailureALotDuringConcMark;
+  }
+  if (during_initial_mark) {
+    res |= G1EvacuationFailureALotDuringInitialMark;
+  }
+  if (gcs_are_young) {
+    res |= G1EvacuationFailureALotDuringYoungGC;
+  } else {
+    // GCs are mixed
+    res |= G1EvacuationFailureALotDuringMixedGC;
+  }
+  return res;
+}
+
+inline void
+G1CollectedHeap::set_evacuation_failure_alot_for_current_gc() {
+  if (G1EvacuationFailureALot) {
+    // Note we can't assert that _evacuation_failure_alot_for_current_gc
+    // is clear here. It may have been set during a previous GC but that GC
+    // did not copy enough objects (i.e. G1EvacuationFailureALotCount) to
+    // trigger an evacuation failure and clear the flags and and counts.
+
+    // Check if we have gone over the interval.
+    const size_t gc_num = total_collections();
+    const size_t elapsed_gcs = gc_num - _evacuation_failure_alot_gc_number;
+
+    _evacuation_failure_alot_for_current_gc = (elapsed_gcs >= G1EvacuationFailureALotInterval);
+
+    // Now check if G1EvacuationFailureALot is enabled for the current GC type.
+    const bool gcs_are_young = g1_policy()->gcs_are_young();
+    const bool during_im = g1_policy()->during_initial_mark_pause();
+    const bool during_marking = mark_in_progress();
+
+    _evacuation_failure_alot_for_current_gc &=
+      evacuation_failure_alot_for_gc_type(gcs_are_young,
+                                          during_im,
+                                          during_marking);
+  }
+}
+
+inline bool
+G1CollectedHeap::evacuation_should_fail() {
+  if (!G1EvacuationFailureALot || !_evacuation_failure_alot_for_current_gc) {
+    return false;
+  }
+  // G1EvacuationFailureALot is in effect for current GC
+  // Access to _evacuation_failure_alot_count is not atomic;
+  // the value does not have to be exact.
+  if (++_evacuation_failure_alot_count < G1EvacuationFailureALotCount) {
+    return false;
+  }
+  _evacuation_failure_alot_count = 0;
+  return true;
+}
+
+inline void G1CollectedHeap::reset_evacuation_should_fail() {
+  if (G1EvacuationFailureALot) {
+    _evacuation_failure_alot_gc_number = total_collections();
+    _evacuation_failure_alot_count = 0;
+    _evacuation_failure_alot_for_current_gc = false;
+  }
+}
+#endif  // #ifndef PRODUCT
+
 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_G1COLLECTEDHEAP_INLINE_HPP

src/share/vm/gc_implementation/g1/g1_globals.hpp

@@ -311,7 +311,35 @@
           "as a percentage of the heap size.")                              \
                                                                             \
   experimental(ccstr, G1LogLevel, NULL,                                     \
-          "Log level for G1 logging: fine, finer, finest")
+          "Log level for G1 logging: fine, finer, finest")                  \
+                                                                            \
+  notproduct(bool, G1EvacuationFailureALot, false,                          \
+          "Force use of evacuation failure handling during certain "        \
+          "evacuation pauses")                                              \
+                                                                            \
+  develop(uintx, G1EvacuationFailureALotCount, 1000,                        \
+          "Number of successful evacuations between evacuation failures "   \
+          "occurring at object copying")                                    \
+                                                                            \
+  develop(uintx, G1EvacuationFailureALotInterval, 5,                        \
+          "Total collections between forced triggering of evacuation "      \
+          "failures")                                                       \
+                                                                            \
+  develop(bool, G1EvacuationFailureALotDuringConcMark, true,                \
+          "Force use of evacuation failure handling during evacuation "     \
+          "pauses when marking is in progress")                             \
+                                                                            \
+  develop(bool, G1EvacuationFailureALotDuringInitialMark, true,             \
+          "Force use of evacuation failure handling during initial mark "   \
+          "evacuation pauses")                                              \
+                                                                            \
+  develop(bool, G1EvacuationFailureALotDuringYoungGC, true,                 \
+          "Force use of evacuation failure handling during young "          \
+          "evacuation pauses")                                              \
+                                                                            \
+  develop(bool, G1EvacuationFailureALotDuringMixedGC, true,                 \
+          "Force use of evacuation failure handling during mixed "          \
+          "evacuation pauses")
 
 G1_FLAGS(DECLARE_DEVELOPER_FLAG, DECLARE_PD_DEVELOPER_FLAG, DECLARE_PRODUCT_FLAG, DECLARE_PD_PRODUCT_FLAG, DECLARE_DIAGNOSTIC_FLAG, DECLARE_EXPERIMENTAL_FLAG, DECLARE_NOTPRODUCT_FLAG, DECLARE_MANAGEABLE_FLAG, DECLARE_PRODUCT_RW_FLAG)