Merge

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

@@ -6536,6 +6536,9 @@ class G1FreeHumongousRegionClosure : public HeapRegionClosure {
 
     G1CollectedHeap* g1h = G1CollectedHeap::heap();
 
+    oop obj = (oop)r->bottom();
+    CMBitMap* next_bitmap = g1h->concurrent_mark()->nextMarkBitMap();
+
     // The following checks whether the humongous object is live are sufficient.
     // The main additional check (in addition to having a reference from the roots
     // or the young gen) is whether the humongous object has a remembered set entry.
@@ -6572,37 +6575,41 @@ class G1FreeHumongousRegionClosure : public HeapRegionClosure {
         g1h->humongous_region_is_always_live(region_idx)) {
 
       if (G1TraceReclaimDeadHumongousObjectsAtYoungGC) {
-        gclog_or_tty->print_cr("Live humongous %d region %d with remset "SIZE_FORMAT" code roots "SIZE_FORMAT" is dead-bitmap %d live-other %d obj array %d",
+        gclog_or_tty->print_cr("Live humongous %d region %d with remset "SIZE_FORMAT" code roots "SIZE_FORMAT" is marked %d live-other %d obj array %d",
                                r->isHumongous(),
                                region_idx,
                                r->rem_set()->occupied(),
                                r->rem_set()->strong_code_roots_list_length(),
-                               g1h->mark_in_progress() && !g1h->g1_policy()->during_initial_mark_pause(),
+                               next_bitmap->isMarked(r->bottom()),
                                g1h->humongous_is_live(region_idx),
-                               oop(r->bottom())->is_objArray()
+                               obj->is_objArray()
                               );
       }
 
       return false;
     }
 
-    guarantee(!((oop)(r->bottom()))->is_objArray(),
+    guarantee(!obj->is_objArray(),
               err_msg("Eagerly reclaiming object arrays is not supported, but the object "PTR_FORMAT" is.",
                       r->bottom()));
 
     if (G1TraceReclaimDeadHumongousObjectsAtYoungGC) {
-      gclog_or_tty->print_cr("Reclaim humongous region %d start "PTR_FORMAT" region %d length "UINT32_FORMAT" with remset "SIZE_FORMAT" code roots "SIZE_FORMAT" is dead-bitmap %d live-other %d obj array %d",
+      gclog_or_tty->print_cr("Reclaim humongous region %d start "PTR_FORMAT" region %d length "UINT32_FORMAT" with remset "SIZE_FORMAT" code roots "SIZE_FORMAT" is marked %d live-other %d obj array %d",
                              r->isHumongous(),
                              r->bottom(),
                              region_idx,
                              r->region_num(),
                              r->rem_set()->occupied(),
                              r->rem_set()->strong_code_roots_list_length(),
-                             g1h->mark_in_progress() && !g1h->g1_policy()->during_initial_mark_pause(),
+                             next_bitmap->isMarked(r->bottom()),
                              g1h->humongous_is_live(region_idx),
-                             oop(r->bottom())->is_objArray()
+                             obj->is_objArray()
                             );
     }
+    // Need to clear mark bit of the humongous object if already set.
+    if (next_bitmap->isMarked(r->bottom())) {
+      next_bitmap->clear(r->bottom());
+    }
     _freed_bytes += r->used();
     r->set_containing_set(NULL);
     _humongous_regions_removed.increment(1u, r->capacity());

hotspot/src/share/vm/gc_implementation/g1/g1ParScanThreadState.cpp

@@ -288,7 +288,12 @@ void G1ParScanThreadState::undo_allocation(GCAllocPurpose purpose, HeapWord* obj
 }
 
 HeapWord* G1ParScanThreadState::allocate(GCAllocPurpose purpose, size_t word_sz) {
-  HeapWord* obj = alloc_buffer(purpose)->allocate(word_sz);
+  HeapWord* obj = NULL;
+  if (purpose == GCAllocForSurvived) {
+    obj = alloc_buffer(GCAllocForSurvived)->allocate_aligned(word_sz, SurvivorAlignmentInBytes);
+  } else {
+    obj = alloc_buffer(GCAllocForTenured)->allocate(word_sz);
+  }
   if (obj != NULL) {
     return obj;
   }

hotspot/src/share/vm/gc_implementation/parNew/parNewGeneration.cpp

@@ -28,12 +28,12 @@
 #include "gc_implementation/parNew/parOopClosures.inline.hpp"
 #include "gc_implementation/shared/adaptiveSizePolicy.hpp"
 #include "gc_implementation/shared/ageTable.hpp"
-#include "gc_implementation/shared/parGCAllocBuffer.hpp"
+#include "gc_implementation/shared/copyFailedInfo.hpp"
 #include "gc_implementation/shared/gcHeapSummary.hpp"
 #include "gc_implementation/shared/gcTimer.hpp"
 #include "gc_implementation/shared/gcTrace.hpp"
 #include "gc_implementation/shared/gcTraceTime.hpp"
-#include "gc_implementation/shared/copyFailedInfo.hpp"
+#include "gc_implementation/shared/parGCAllocBuffer.inline.hpp"
 #include "gc_implementation/shared/spaceDecorator.hpp"
 #include "memory/defNewGeneration.inline.hpp"
 #include "memory/genCollectedHeap.hpp"
@@ -252,7 +252,7 @@ HeapWord* ParScanThreadState::alloc_in_to_space_slow(size_t word_sz) {
         plab->set_word_size(buf_size);
         plab->set_buf(buf_space);
         record_survivor_plab(buf_space, buf_size);
-        obj = plab->allocate(word_sz);
+        obj = plab->allocate_aligned(word_sz, SurvivorAlignmentInBytes);
         // Note that we cannot compare buf_size < word_sz below
         // because of AlignmentReserve (see ParGCAllocBuffer::allocate()).
         assert(obj != NULL || plab->words_remaining() < word_sz,

hotspot/src/share/vm/gc_implementation/parNew/parNewGeneration.hpp

@@ -168,7 +168,7 @@ class ParScanThreadState {
   HeapWord* alloc_in_to_space_slow(size_t word_sz);
 
   HeapWord* alloc_in_to_space(size_t word_sz) {
-    HeapWord* obj = to_space_alloc_buffer()->allocate(word_sz);
+    HeapWord* obj = to_space_alloc_buffer()->allocate_aligned(word_sz, SurvivorAlignmentInBytes);
     if (obj != NULL) return obj;
     else return alloc_in_to_space_slow(word_sz);
   }

hotspot/src/share/vm/gc_implementation/parallelScavenge/psPromotionLAB.hpp

@@ -26,6 +26,7 @@
 #define SHARE_VM_GC_IMPLEMENTATION_PARALLELSCAVENGE_PSPROMOTIONLAB_HPP
 
 #include "gc_implementation/parallelScavenge/objectStartArray.hpp"
+#include "gc_interface/collectedHeap.inline.hpp"
 #include "memory/allocation.hpp"
 
 //
@@ -94,23 +95,9 @@ class PSYoungPromotionLAB : public PSPromotionLAB {
   PSYoungPromotionLAB() { }
 
   // Not MT safe
-  HeapWord* allocate(size_t size) {
+  inline HeapWord* allocate(size_t size);
-    // Can't assert this, when young fills, we keep the LAB around, but flushed.
-    // assert(_state != flushed, "Sanity");
-    HeapWord* obj = top();
-    HeapWord* new_top = obj + size;
-    // The 'new_top>obj' check is needed to detect overflow of obj+size.
-    if (new_top > obj && new_top <= end()) {
-      set_top(new_top);
-      assert(is_object_aligned((intptr_t)obj) && is_object_aligned((intptr_t)new_top),
-             "checking alignment");
-      return obj;
-    }
 
-    return NULL;
+  debug_only(virtual bool lab_is_valid(MemRegion lab);)
-  }
-
-  debug_only(virtual bool lab_is_valid(MemRegion lab));
 };
 
 class PSOldPromotionLAB : public PSPromotionLAB {

hotspot/src/share/vm/gc_implementation/parallelScavenge/psPromotionLAB.inline.hpp

@@ -0,0 +1,52 @@
+/*
+ * 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.
+ *
+ */
+
+#ifndef SHARE_VM_GC_IMPLEMENTATION_PARALLELSCAVENGE_PSPROMOTIONLAB_INLINE_HPP
+#define SHARE_VM_GC_IMPLEMENTATION_PARALLELSCAVENGE_PSPROMOTIONLAB_INLINE_HPP
+
+#include "gc_implementation/parallelScavenge/psPromotionLAB.hpp"
+#include "gc_interface/collectedHeap.inline.hpp"
+
+HeapWord* PSYoungPromotionLAB::allocate(size_t size) {
+  // Can't assert this, when young fills, we keep the LAB around, but flushed.
+  // assert(_state != flushed, "Sanity");
+  HeapWord* obj = CollectedHeap::align_allocation_or_fail(top(), end(), SurvivorAlignmentInBytes);
+  if (obj == NULL) {
+    return NULL;
+  }
+
+  HeapWord* new_top = obj + size;
+  // The 'new_top>obj' check is needed to detect overflow of obj+size.
+  if (new_top > obj && new_top <= end()) {
+    set_top(new_top);
+    assert(is_ptr_aligned(obj, SurvivorAlignmentInBytes) && is_object_aligned((intptr_t)new_top),
+           "checking alignment");
+    return obj;
+  } else {
+    set_top(obj);
+    return NULL;
+  }
+}
+
+#endif // SHARE_VM_GC_IMPLEMENTATION_PARALLELSCAVENGE_PSPROMOTIONLAB_INLINE_HPP

hotspot/src/share/vm/gc_implementation/parallelScavenge/psPromotionManager.inline.hpp

@@ -27,6 +27,7 @@
 
 #include "gc_implementation/parallelScavenge/psOldGen.hpp"
 #include "gc_implementation/parallelScavenge/psPromotionManager.hpp"
+#include "gc_implementation/parallelScavenge/psPromotionLAB.inline.hpp"
 #include "gc_implementation/parallelScavenge/psScavenge.hpp"
 #include "oops/oop.psgc.inline.hpp"
 

hotspot/src/share/vm/gc_implementation/shared/parGCAllocBuffer.hpp

@@ -24,7 +24,7 @@
 
 #ifndef SHARE_VM_GC_IMPLEMENTATION_PARNEW_PARGCALLOCBUFFER_HPP
 #define SHARE_VM_GC_IMPLEMENTATION_PARNEW_PARGCALLOCBUFFER_HPP
-
+#include "gc_interface/collectedHeap.hpp"
 #include "memory/allocation.hpp"
 #include "memory/blockOffsetTable.hpp"
 #include "memory/threadLocalAllocBuffer.hpp"
@@ -84,6 +84,9 @@ public:
     }
   }
 
+  // Allocate the object aligned to "alignment_in_bytes".
+  HeapWord* allocate_aligned(size_t word_sz, unsigned short alignment_in_bytes);
+
   // Undo the last allocation in the buffer, which is required to be of the
   // "obj" of the given "word_sz".
   void undo_allocation(HeapWord* obj, size_t word_sz) {

hotspot/src/share/vm/gc_implementation/shared/parGCAllocBuffer.inline.hpp

@@ -0,0 +1,44 @@
+/*
+ * 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.
+ *
+ */
+
+#ifndef SHARE_VM_GC_IMPLEMENTATION_SHARED_PARGCALLOCBUFFER_INLINE_HPP
+#define SHARE_VM_GC_IMPLEMENTATION_SHARED_PARGCALLOCBUFFER_INLINE_HPP
+
+#include "gc_implementation/shared/parGCAllocBuffer.hpp"
+#include "gc_interface/collectedHeap.inline.hpp"
+
+HeapWord* ParGCAllocBuffer::allocate_aligned(size_t word_sz, unsigned short alignment_in_bytes) {
+
+  HeapWord* res = CollectedHeap::align_allocation_or_fail(_top, _end, alignment_in_bytes);
+  if (res == NULL) {
+    return NULL;
+  }
+
+  // Set _top so that allocate(), which expects _top to be correctly set,
+  // can be used below.
+  _top = res;
+  return allocate(word_sz);
+}
+
+#endif // SHARE_VM_GC_IMPLEMENTATION_SHARED_PARGCALLOCBUFFER_INLINE_HPP

hotspot/src/share/vm/gc_interface/collectedHeap.hpp

@@ -351,6 +351,12 @@ class CollectedHeap : public CHeapObj<mtInternal> {
     fill_with_object(start, pointer_delta(end, start), zap);
   }
 
+  // Return the address "addr" aligned by "alignment_in_bytes" if such
+  // an address is below "end".  Return NULL otherwise.
+  inline static HeapWord* align_allocation_or_fail(HeapWord* addr,
+                                                   HeapWord* end,
+                                                   unsigned short alignment_in_bytes);
+
   // Some heaps may offer a contiguous region for shared non-blocking
   // allocation, via inlined code (by exporting the address of the top and
   // end fields defining the extent of the contiguous allocation region.)

hotspot/src/share/vm/gc_interface/collectedHeap.inline.hpp

@@ -241,6 +241,44 @@ inline void CollectedHeap::oop_iterate_no_header(OopClosure* cl) {
   oop_iterate(&no_header_cl);
 }
 
+
+inline HeapWord* CollectedHeap::align_allocation_or_fail(HeapWord* addr,
+                                                         HeapWord* end,
+                                                         unsigned short alignment_in_bytes) {
+  if (alignment_in_bytes <= ObjectAlignmentInBytes) {
+    return addr;
+  }
+
+  assert(is_ptr_aligned(addr, HeapWordSize),
+    err_msg("Address " PTR_FORMAT " is not properly aligned.", p2i(addr)));
+  assert(is_size_aligned(alignment_in_bytes, HeapWordSize),
+    err_msg("Alignment size %u is incorrect.", alignment_in_bytes));
+
+  HeapWord* new_addr = (HeapWord*) align_pointer_up(addr, alignment_in_bytes);
+  size_t padding = pointer_delta(new_addr, addr);
+
+  if (padding == 0) {
+    return addr;
+  }
+
+  if (padding < CollectedHeap::min_fill_size()) {
+    padding += alignment_in_bytes / HeapWordSize;
+    assert(padding >= CollectedHeap::min_fill_size(),
+      err_msg("alignment_in_bytes %u is expect to be larger "
+      "than the minimum object size", alignment_in_bytes));
+    new_addr = addr + padding;
+  }
+
+  assert(new_addr > addr, err_msg("Unexpected arithmetic overflow "
+    PTR_FORMAT " not greater than " PTR_FORMAT, p2i(new_addr), p2i(addr)));
+  if(new_addr < end) {
+    CollectedHeap::fill_with_object(addr, padding);
+    return new_addr;
+  } else {
+    return NULL;
+  }
+}
+
 #ifndef PRODUCT
 
 inline bool

hotspot/src/share/vm/memory/defNewGeneration.cpp

@@ -790,7 +790,7 @@ oop DefNewGeneration::copy_to_survivor_space(oop old) {
 
   // Try allocating obj in to-space (unless too old)
   if (old->age() < tenuring_threshold()) {
-    obj = (oop) to()->allocate(s);
+    obj = (oop) to()->allocate_aligned(s);
   }
 
   // Otherwise try allocating obj tenured

hotspot/src/share/vm/memory/space.cpp

@@ -28,6 +28,7 @@
 #include "gc_implementation/shared/liveRange.hpp"
 #include "gc_implementation/shared/markSweep.hpp"
 #include "gc_implementation/shared/spaceDecorator.hpp"
+#include "gc_interface/collectedHeap.inline.hpp"
 #include "memory/blockOffsetTable.inline.hpp"
 #include "memory/defNewGeneration.hpp"
 #include "memory/genCollectedHeap.hpp"
@@ -720,6 +721,27 @@ inline HeapWord* ContiguousSpace::par_allocate_impl(size_t size,
   } while (true);
 }
 
+HeapWord* ContiguousSpace::allocate_aligned(size_t size) {
+  assert(Heap_lock->owned_by_self() || (SafepointSynchronize::is_at_safepoint() && Thread::current()->is_VM_thread()), "not locked");
+  HeapWord* end_value = end();
+
+  HeapWord* obj = CollectedHeap::align_allocation_or_fail(top(), end_value, SurvivorAlignmentInBytes);
+  if (obj == NULL) {
+    return NULL;
+  }
+
+  if (pointer_delta(end_value, obj) >= size) {
+    HeapWord* new_top = obj + size;
+    set_top(new_top);
+    assert(is_ptr_aligned(obj, SurvivorAlignmentInBytes) && is_aligned(new_top),
+      "checking alignment");
+    return obj;
+  } else {
+    set_top(obj);
+    return NULL;
+  }
+}
+
 // Requires locking.
 HeapWord* ContiguousSpace::allocate(size_t size) {
   return allocate_impl(size, end());

hotspot/src/share/vm/memory/space.hpp

@@ -526,6 +526,7 @@ class ContiguousSpace: public CompactibleSpace {
   // Allocation (return NULL if full)
   virtual HeapWord* allocate(size_t word_size);
   virtual HeapWord* par_allocate(size_t word_size);
+  HeapWord* allocate_aligned(size_t word_size);
 
   // Iteration
   void oop_iterate(ExtendedOopClosure* cl);

hotspot/src/share/vm/oops/oop.pcgc.inline.hpp

@@ -55,8 +55,6 @@ inline void oopDesc::follow_contents(ParCompactionManager* cm) {
   klass()->oop_follow_contents(cm, this);
 }
 
-// Used by parallel old GC.
-
 inline oop oopDesc::forward_to_atomic(oop p) {
   assert(ParNewGeneration::is_legal_forward_ptr(p),
          "illegal forwarding pointer value.");

hotspot/src/share/vm/runtime/arguments.cpp

@@ -1431,6 +1431,22 @@ bool verify_object_alignment() {
                 (int)ObjectAlignmentInBytes, os::vm_page_size());
     return false;
   }
+  if(SurvivorAlignmentInBytes == 0) {
+    SurvivorAlignmentInBytes = ObjectAlignmentInBytes;
+  } else {
+    if (!is_power_of_2(SurvivorAlignmentInBytes)) {
+      jio_fprintf(defaultStream::error_stream(),
+            "error: SurvivorAlignmentInBytes=%d must be power of 2\n",
+            (int)SurvivorAlignmentInBytes);
+      return false;
+    }
+    if (SurvivorAlignmentInBytes < ObjectAlignmentInBytes) {
+      jio_fprintf(defaultStream::error_stream(),
+          "error: SurvivorAlignmentInBytes=%d must be greater than ObjectAlignmentInBytes=%d \n",
+          (int)SurvivorAlignmentInBytes, (int)ObjectAlignmentInBytes);
+      return false;
+    }
+  }
   return true;
 }
 

hotspot/src/share/vm/runtime/globals.hpp

@@ -3871,6 +3871,9 @@ class CommandLineFlags {
   product(bool, PrintGCCause, true,                                         \
           "Include GC cause in GC logging")                                 \
                                                                             \
+  experimental(intx, SurvivorAlignmentInBytes, 0,                           \
+           "Default survivor space alignment in bytes")                     \
+                                                                            \
   product(bool , AllowNonVirtualCalls, false,                               \
           "Obey the ACC_SUPER flag and allow invokenonvirtual calls")       \
                                                                             \

hotspot/test/gc/g1/TestEagerReclaimHumongousRegions2.java

@@ -0,0 +1,122 @@
+/*
+ * 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 TestEagerReclaimHumongousRegions2
+ * @bug 8051973
+ * @summary Test to make sure that eager reclaim of humongous objects correctly clears
+ * mark bitmaps at reclaim.
+ * @key gc
+ * @library /testlibrary
+ */
+
+import java.util.ArrayList;
+import java.util.LinkedList;
+import java.util.Random;
+
+import com.oracle.java.testlibrary.OutputAnalyzer;
+import com.oracle.java.testlibrary.ProcessTools;
+
+// An object that has a few references to other instances to slow down marking.
+class ObjectWithSomeRefs {
+    public ObjectWithSomeRefs other1;
+    public ObjectWithSomeRefs other2;
+    public ObjectWithSomeRefs other3;
+    public ObjectWithSomeRefs other4;
+}
+
+class ReclaimRegionFast {
+    public static final int M = 1024*1024;
+
+    public static LinkedList<Object> garbageList = new LinkedList<Object>();
+
+    public static void genGarbage(Object large) {
+        for (int i = 0; i < 64*1024; i++) {
+            Object[] garbage = new Object[50];
+            garbage[0] = large;
+            garbageList.add(garbage);
+        }
+        garbageList.clear();
+    }
+
+    public static ArrayList<ObjectWithSomeRefs> longList = new ArrayList<ObjectWithSomeRefs>();
+
+    public static void main(String[] args) {
+
+        for (int i = 0; i < 16*1024; i++) {
+             longList.add(new ObjectWithSomeRefs());
+        }
+
+        Random rnd = new Random();
+        for (int i = 0; i < longList.size(); i++) {
+             int len = longList.size();
+             longList.get(i).other1 = longList.get(rnd.nextInt(len));
+             longList.get(i).other2 = longList.get(rnd.nextInt(len));
+             longList.get(i).other3 = longList.get(rnd.nextInt(len));
+             longList.get(i).other4 = longList.get(rnd.nextInt(len));
+        }
+
+        int[] large1 = new int[M];
+        int[] large2 = null;
+        int[] large3 = null;
+        int[] large4 = null;
+
+        Object ref_from_stack = large1;
+
+        for (int i = 0; i < 20; i++) {
+            // A set of large objects that will be reclaimed eagerly - and hopefully marked.
+            large1 = new int[M - 20];
+            large2 = new int[M - 20];
+            large3 = new int[M - 20];
+            large4 = new int[M - 20];
+            genGarbage(large1);
+            // Make sure that the compiler cannot completely remove
+            // the allocation of the large object until here.
+            System.out.println(large1 + " " + large2 + " " + large3 + " " + large4);
+        }
+
+        // Keep the reference to the first object alive.
+        System.out.println(ref_from_stack);
+    }
+}
+
+public class TestEagerReclaimHumongousRegions2 {
+    public static void main(String[] args) throws Exception {
+        ProcessBuilder pb = ProcessTools.createJavaProcessBuilder(
+            "-XX:+UseG1GC",
+            "-Xms128M",
+            "-Xmx128M",
+            "-Xmn2M",
+            "-XX:G1HeapRegionSize=1M",
+            "-XX:InitiatingHeapOccupancyPercent=0", // Want to have as much as possible initial marks.
+            "-XX:+PrintGC",
+            "-XX:+VerifyAfterGC",
+            "-XX:ConcGCThreads=1", // Want to make marking as slow as possible.
+            "-XX:+IgnoreUnrecognizedVMOptions", // G1VerifyBitmaps is develop only.
+            "-XX:+G1VerifyBitmaps",
+            ReclaimRegionFast.class.getName());
+        OutputAnalyzer output = new OutputAnalyzer(pb.start());
+        output.shouldHaveExitValue(0);
+    }
+}
+