8003720: NPG: Method in interpreter stack frame can be deallocated

Summary: Pass down a closure during root scanning to keep the class of the method alive.
Reviewed-by: coleenp, jcoomes

src/share/vm/gc_implementation/parallelScavenge/pcTasks.cpp

@@ -52,14 +52,22 @@ void ThreadRootsMarkingTask::do_it(GCTaskManager* manager, uint which) {
     PrintGCDetails && TraceParallelOldGCTasks, true, gclog_or_tty));
   ParCompactionManager* cm =
     ParCompactionManager::gc_thread_compaction_manager(which);
+
   PSParallelCompact::MarkAndPushClosure mark_and_push_closure(cm);
+  CLDToOopClosure mark_and_push_from_clds(&mark_and_push_closure, true);
   CodeBlobToOopClosure mark_and_push_in_blobs(&mark_and_push_closure, /*do_marking=*/ true);
 
   if (_java_thread != NULL)
-    _java_thread->oops_do(&mark_and_push_closure, &mark_and_push_in_blobs);
+    _java_thread->oops_do(
+        &mark_and_push_closure,
+        &mark_and_push_from_clds,
+        &mark_and_push_in_blobs);
 
   if (_vm_thread != NULL)
-    _vm_thread->oops_do(&mark_and_push_closure, &mark_and_push_in_blobs);
+    _vm_thread->oops_do(
+        &mark_and_push_closure,
+        &mark_and_push_from_clds,
+        &mark_and_push_in_blobs);
 
   // Do the real work
   cm->follow_marking_stacks();
@@ -89,7 +97,8 @@ void MarkFromRootsTask::do_it(GCTaskManager* manager, uint which) {
     {
       ResourceMark rm;
       CodeBlobToOopClosure each_active_code_blob(&mark_and_push_closure, /*do_marking=*/ true);
-      Threads::oops_do(&mark_and_push_closure, &each_active_code_blob);
+      CLDToOopClosure mark_and_push_from_cld(&mark_and_push_closure);
+      Threads::oops_do(&mark_and_push_closure, &mark_and_push_from_cld, &each_active_code_blob);
     }
     break;
 

src/share/vm/gc_implementation/parallelScavenge/psMarkSweep.cpp

@@ -495,8 +495,9 @@ void PSMarkSweep::mark_sweep_phase1(bool clear_all_softrefs) {
     ParallelScavengeHeap::ParStrongRootsScope psrs;
     Universe::oops_do(mark_and_push_closure());
     JNIHandles::oops_do(mark_and_push_closure());   // Global (strong) JNI handles
+    CLDToOopClosure mark_and_push_from_cld(mark_and_push_closure());
     CodeBlobToOopClosure each_active_code_blob(mark_and_push_closure(), /*do_marking=*/ true);
-    Threads::oops_do(mark_and_push_closure(), &each_active_code_blob);
+    Threads::oops_do(mark_and_push_closure(), &mark_and_push_from_cld, &each_active_code_blob);
     ObjectSynchronizer::oops_do(mark_and_push_closure());
     FlatProfiler::oops_do(mark_and_push_closure());
     Management::oops_do(mark_and_push_closure());
@@ -584,7 +585,8 @@ void PSMarkSweep::mark_sweep_phase3() {
   // General strong roots.
   Universe::oops_do(adjust_root_pointer_closure());
   JNIHandles::oops_do(adjust_root_pointer_closure());   // Global (strong) JNI handles
-  Threads::oops_do(adjust_root_pointer_closure(), NULL);
+  CLDToOopClosure adjust_from_cld(adjust_root_pointer_closure());
+  Threads::oops_do(adjust_root_pointer_closure(), &adjust_from_cld, NULL);
   ObjectSynchronizer::oops_do(adjust_root_pointer_closure());
   FlatProfiler::oops_do(adjust_root_pointer_closure());
   Management::oops_do(adjust_root_pointer_closure());

src/share/vm/gc_implementation/parallelScavenge/psParallelCompact.cpp

@@ -2436,7 +2436,8 @@ void PSParallelCompact::adjust_roots() {
   // General strong roots.
   Universe::oops_do(adjust_root_pointer_closure());
   JNIHandles::oops_do(adjust_root_pointer_closure());   // Global (strong) JNI handles
-  Threads::oops_do(adjust_root_pointer_closure(), NULL);
+  CLDToOopClosure adjust_from_cld(adjust_root_pointer_closure());
+  Threads::oops_do(adjust_root_pointer_closure(), &adjust_from_cld, NULL);
   ObjectSynchronizer::oops_do(adjust_root_pointer_closure());
   FlatProfiler::oops_do(adjust_root_pointer_closure());
   Management::oops_do(adjust_root_pointer_closure());

src/share/vm/gc_implementation/parallelScavenge/psTasks.cpp

@@ -65,7 +65,8 @@ void ScavengeRootsTask::do_it(GCTaskManager* manager, uint which) {
     case threads:
     {
       ResourceMark rm;
-      Threads::oops_do(&roots_closure, NULL);
+      CLDToOopClosure* cld_closure = NULL; // Not needed. All CLDs are already visited.
+      Threads::oops_do(&roots_closure, cld_closure, NULL);
     }
     break;
 
@@ -120,13 +121,14 @@ void ThreadRootsTask::do_it(GCTaskManager* manager, uint which) {
 
   PSPromotionManager* pm = PSPromotionManager::gc_thread_promotion_manager(which);
   PSScavengeRootsClosure roots_closure(pm);
+  CLDToOopClosure* roots_from_clds = NULL;  // Not needed. All CLDs are already visited.
   CodeBlobToOopClosure roots_in_blobs(&roots_closure, /*do_marking=*/ true);
 
   if (_java_thread != NULL)
-    _java_thread->oops_do(&roots_closure, &roots_in_blobs);
+    _java_thread->oops_do(&roots_closure, roots_from_clds, &roots_in_blobs);
 
   if (_vm_thread != NULL)
-    _vm_thread->oops_do(&roots_closure, &roots_in_blobs);
+    _vm_thread->oops_do(&roots_closure, roots_from_clds, &roots_in_blobs);
 
   // Do the real work
   pm->drain_stacks(false);

src/share/vm/memory/iterator.cpp

@@ -30,6 +30,10 @@ void KlassToOopClosure::do_klass(Klass* k) {
   k->oops_do(_oop_closure);
 }
 
+void CLDToOopClosure::do_cld(ClassLoaderData* cld) {
+  cld->oops_do(_oop_closure, &_klass_closure, _must_claim_cld);
+}
+
 void ObjectToOopClosure::do_object(oop obj) {
   obj->oop_iterate(_cl);
 }

src/share/vm/memory/iterator.hpp

@@ -135,6 +135,20 @@ class KlassToOopClosure : public KlassClosure {
   virtual void do_klass(Klass* k);
 };
 
+class CLDToOopClosure {
+  OopClosure* _oop_closure;
+  KlassToOopClosure _klass_closure;
+  bool _must_claim_cld;
+
+ public:
+  CLDToOopClosure(OopClosure* oop_closure, bool must_claim_cld = true) :
+      _oop_closure(oop_closure),
+      _klass_closure(oop_closure),
+      _must_claim_cld(must_claim_cld) {}
+
+  void do_cld(ClassLoaderData* cld);
+};
+
 // ObjectClosure is used for iterating through an object space
 
 class ObjectClosure : public Closure {

src/share/vm/memory/sharedHeap.cpp

@@ -154,10 +154,12 @@ void SharedHeap::process_strong_roots(bool activate_scope,
   if (!_process_strong_tasks->is_task_claimed(SH_PS_JNIHandles_oops_do))
     JNIHandles::oops_do(roots);
   // All threads execute this; the individual threads are task groups.
+  CLDToOopClosure roots_from_clds(roots);
+  CLDToOopClosure* roots_from_clds_p = (is_scavenging ? NULL : &roots_from_clds);
   if (ParallelGCThreads > 0) {
-    Threads::possibly_parallel_oops_do(roots, code_roots);
+    Threads::possibly_parallel_oops_do(roots, roots_from_clds_p ,code_roots);
   } else {
-    Threads::oops_do(roots, code_roots);
+    Threads::oops_do(roots, roots_from_clds_p, code_roots);
   }
   if (!_process_strong_tasks-> is_task_claimed(SH_PS_ObjectSynchronizer_oops_do))
     ObjectSynchronizer::oops_do(roots);

src/share/vm/runtime/deoptimization.cpp

@@ -721,7 +721,7 @@ JRT_LEAF(BasicType, Deoptimization::unpack_frames(JavaThread* thread, int exec_m
         guarantee(false, "wrong number of expression stack elements during deopt");
       }
       VerifyOopClosure verify;
-      iframe->oops_interpreted_do(&verify, &rm, false);
+      iframe->oops_interpreted_do(&verify, NULL, &rm, false);
       callee_size_of_parameters = mh->size_of_parameters();
       callee_max_locals = mh->max_locals();
       is_top_frame = false;

src/share/vm/runtime/frame.cpp

@@ -879,7 +879,8 @@ oop* frame::interpreter_callee_receiver_addr(Symbol* signature) {
 }
 
 
-void frame::oops_interpreted_do(OopClosure* f, const RegisterMap* map, bool query_oop_map_cache) {
+void frame::oops_interpreted_do(OopClosure* f, CLDToOopClosure* cld_f,
+    const RegisterMap* map, bool query_oop_map_cache) {
   assert(is_interpreted_frame(), "Not an interpreted frame");
   assert(map != NULL, "map must be set");
   Thread *thread = Thread::current();
@@ -906,6 +907,16 @@ void frame::oops_interpreted_do(OopClosure* f, const RegisterMap* map, bool quer
   }
 
   // process fixed part
+  if (cld_f != NULL) {
+    // The method pointer in the frame might be the only path to the method's
+    // klass, and the klass needs to be kept alive while executing. The GCs
+    // don't trace through method pointers, so typically in similar situations
+    // the mirror or the class loader of the klass are installed as a GC root.
+    // To minimze the overhead of doing that here, we ask the GC to pass down a
+    // closure that knows how to keep klasses alive given a ClassLoaderData.
+    cld_f->do_cld(m->method_holder()->class_loader_data());
+  }
+
 #if !defined(PPC) || defined(ZERO)
   if (m->is_native()) {
 #ifdef CC_INTERP
@@ -1108,7 +1119,7 @@ void frame::oops_entry_do(OopClosure* f, const RegisterMap* map) {
 }
 
 
-void frame::oops_do_internal(OopClosure* f, CodeBlobClosure* cf, RegisterMap* map, bool use_interpreter_oop_map_cache) {
+void frame::oops_do_internal(OopClosure* f, CLDToOopClosure* cld_f, CodeBlobClosure* cf, RegisterMap* map, bool use_interpreter_oop_map_cache) {
 #ifndef PRODUCT
   // simulate GC crash here to dump java thread in error report
   if (CrashGCForDumpingJavaThread) {
@@ -1117,7 +1128,7 @@ void frame::oops_do_internal(OopClosure* f, CodeBlobClosure* cf, RegisterMap* ma
   }
 #endif
   if (is_interpreted_frame()) {
-    oops_interpreted_do(f, map, use_interpreter_oop_map_cache);
+    oops_interpreted_do(f, cld_f, map, use_interpreter_oop_map_cache);
   } else if (is_entry_frame()) {
     oops_entry_do(f, map);
   } else if (CodeCache::contains(pc())) {
@@ -1278,7 +1289,7 @@ void frame::verify(const RegisterMap* map) {
     }
   }
   COMPILER2_PRESENT(assert(DerivedPointerTable::is_empty(), "must be empty before verify");)
-  oops_do_internal(&VerifyOopClosure::verify_oop, NULL, (RegisterMap*)map, false);
+  oops_do_internal(&VerifyOopClosure::verify_oop, NULL, NULL, (RegisterMap*)map, false);
 }
 
 

src/share/vm/runtime/frame.hpp

@@ -413,19 +413,19 @@ class frame VALUE_OBJ_CLASS_SPEC {
 
   // Oops-do's
   void oops_compiled_arguments_do(Symbol* signature, bool has_receiver, const RegisterMap* reg_map, OopClosure* f);
-  void oops_interpreted_do(OopClosure* f, const RegisterMap* map, bool query_oop_map_cache = true);
+  void oops_interpreted_do(OopClosure* f, CLDToOopClosure* cld_f, const RegisterMap* map, bool query_oop_map_cache = true);
 
  private:
   void oops_interpreted_arguments_do(Symbol* signature, bool has_receiver, OopClosure* f);
 
   // Iteration of oops
-  void oops_do_internal(OopClosure* f, CodeBlobClosure* cf, RegisterMap* map, bool use_interpreter_oop_map_cache);
+  void oops_do_internal(OopClosure* f, CLDToOopClosure* cld_f, CodeBlobClosure* cf, RegisterMap* map, bool use_interpreter_oop_map_cache);
   void oops_entry_do(OopClosure* f, const RegisterMap* map);
   void oops_code_blob_do(OopClosure* f, CodeBlobClosure* cf, const RegisterMap* map);
   int adjust_offset(Method* method, int index); // helper for above fn
  public:
   // Memory management
-  void oops_do(OopClosure* f, CodeBlobClosure* cf, RegisterMap* map) { oops_do_internal(f, cf, map, true); }
+  void oops_do(OopClosure* f, CLDToOopClosure* cld_f, CodeBlobClosure* cf, RegisterMap* map) { oops_do_internal(f, cld_f, cf, map, true); }
   void nmethods_do(CodeBlobClosure* cf);
 
   // RedefineClasses support for finding live interpreted methods on the stack

src/share/vm/runtime/thread.cpp

@@ -826,7 +826,7 @@ bool Thread::claim_oops_do_par_case(int strong_roots_parity) {
   return false;
 }
 
-void Thread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
+void Thread::oops_do(OopClosure* f, CLDToOopClosure* cld_f, CodeBlobClosure* cf) {
   active_handles()->oops_do(f);
   // Do oop for ThreadShadow
   f->do_oop((oop*)&_pending_exception);
@@ -2705,7 +2705,7 @@ public:
   }
 };
 
-void JavaThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
+void JavaThread::oops_do(OopClosure* f, CLDToOopClosure* cld_f, CodeBlobClosure* cf) {
   // Verify that the deferred card marks have been flushed.
   assert(deferred_card_mark().is_empty(), "Should be empty during GC");
 
@@ -2713,7 +2713,7 @@ void JavaThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
   // since there may be more than one thread using each ThreadProfiler.
 
   // Traverse the GCHandles
-  Thread::oops_do(f, cf);
+  Thread::oops_do(f, cld_f, cf);
 
   assert( (!has_last_Java_frame() && java_call_counter() == 0) ||
           (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
@@ -2741,7 +2741,7 @@ void JavaThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
 
     // Traverse the execution stack
     for(StackFrameStream fst(this); !fst.is_done(); fst.next()) {
-      fst.current()->oops_do(f, cf, fst.register_map());
+      fst.current()->oops_do(f, cld_f, cf, fst.register_map());
     }
   }
 
@@ -2875,7 +2875,7 @@ static void frame_verify(frame* f, const RegisterMap *map) { f->verify(map); }
 
 void JavaThread::verify() {
   // Verify oops in the thread.
-  oops_do(&VerifyOopClosure::verify_oop, NULL);
+  oops_do(&VerifyOopClosure::verify_oop, NULL, NULL);
 
   // Verify the stack frames.
   frames_do(frame_verify);
@@ -3125,7 +3125,7 @@ class PrintAndVerifyOopClosure: public OopClosure {
 static void oops_print(frame* f, const RegisterMap *map) {
   PrintAndVerifyOopClosure print;
   f->print_value();
-  f->oops_do(&print, NULL, (RegisterMap*)map);
+  f->oops_do(&print, NULL, NULL, (RegisterMap*)map);
 }
 
 // Print our all the locations that contain oops and whether they are
@@ -3227,8 +3227,8 @@ CompilerThread::CompilerThread(CompileQueue* queue, CompilerCounters* counters)
 #endif
 }
 
-void CompilerThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
-  JavaThread::oops_do(f, cf);
+void CompilerThread::oops_do(OopClosure* f, CLDToOopClosure* cld_f, CodeBlobClosure* cf) {
+  JavaThread::oops_do(f, cld_f, cf);
   if (_scanned_nmethod != NULL && cf != NULL) {
     // Safepoints can occur when the sweeper is scanning an nmethod so
     // process it here to make sure it isn't unloaded in the middle of
@@ -4201,14 +4201,14 @@ bool Threads::includes(JavaThread* p) {
 // uses the Threads_lock to gurantee this property. It also makes sure that
 // all threads gets blocked when exiting or starting).
 
-void Threads::oops_do(OopClosure* f, CodeBlobClosure* cf) {
+void Threads::oops_do(OopClosure* f, CLDToOopClosure* cld_f, CodeBlobClosure* cf) {
   ALL_JAVA_THREADS(p) {
-    p->oops_do(f, cf);
+    p->oops_do(f, cld_f, cf);
   }
-  VMThread::vm_thread()->oops_do(f, cf);
+  VMThread::vm_thread()->oops_do(f, cld_f, cf);
 }
 
-void Threads::possibly_parallel_oops_do(OopClosure* f, CodeBlobClosure* cf) {
+void Threads::possibly_parallel_oops_do(OopClosure* f, CLDToOopClosure* cld_f, CodeBlobClosure* cf) {
   // Introduce a mechanism allowing parallel threads to claim threads as
   // root groups.  Overhead should be small enough to use all the time,
   // even in sequential code.
@@ -4225,12 +4225,12 @@ void Threads::possibly_parallel_oops_do(OopClosure* f, CodeBlobClosure* cf) {
   int cp = SharedHeap::heap()->strong_roots_parity();
   ALL_JAVA_THREADS(p) {
     if (p->claim_oops_do(is_par, cp)) {
-      p->oops_do(f, cf);
+      p->oops_do(f, cld_f, cf);
     }
   }
   VMThread* vmt = VMThread::vm_thread();
   if (vmt->claim_oops_do(is_par, cp)) {
-    vmt->oops_do(f, cf);
+    vmt->oops_do(f, cld_f, cf);
   }
 }
 

src/share/vm/runtime/thread.hpp

@@ -480,8 +480,10 @@ class Thread: public ThreadShadow {
 
   // GC support
   // Apply "f->do_oop" to all root oops in "this".
+  // Apply "cld_f->do_cld" to CLDs that are otherwise not kept alive.
+  //   Used by JavaThread::oops_do.
   // Apply "cf->do_code_blob" (if !NULL) to all code blobs active in frames
-  virtual void oops_do(OopClosure* f, CodeBlobClosure* cf);
+  virtual void oops_do(OopClosure* f, CLDToOopClosure* cld_f, CodeBlobClosure* cf);
 
   // Handles the parallel case for the method below.
 private:
@@ -1405,7 +1407,7 @@ class JavaThread: public Thread {
   void frames_do(void f(frame*, const RegisterMap*));
 
   // Memory operations
-  void oops_do(OopClosure* f, CodeBlobClosure* cf);
+  void oops_do(OopClosure* f, CLDToOopClosure* cld_f, CodeBlobClosure* cf);
 
   // Sweeper operations
   void nmethods_do(CodeBlobClosure* cf);
@@ -1825,7 +1827,7 @@ class CompilerThread : public JavaThread {
   // GC support
   // Apply "f->do_oop" to all root oops in "this".
   // Apply "cf->do_code_blob" (if !NULL) to all code blobs active in frames
-  void oops_do(OopClosure* f, CodeBlobClosure* cf);
+  void oops_do(OopClosure* f, CLDToOopClosure* cld_f, CodeBlobClosure* cf);
 
 #ifndef PRODUCT
 private:
@@ -1892,9 +1894,9 @@ class Threads: AllStatic {
 
   // Apply "f->do_oop" to all root oops in all threads.
   // This version may only be called by sequential code.
-  static void oops_do(OopClosure* f, CodeBlobClosure* cf);
+  static void oops_do(OopClosure* f, CLDToOopClosure* cld_f, CodeBlobClosure* cf);
   // This version may be called by sequential or parallel code.
-  static void possibly_parallel_oops_do(OopClosure* f, CodeBlobClosure* cf);
+  static void possibly_parallel_oops_do(OopClosure* f, CLDToOopClosure* cld_f, CodeBlobClosure* cf);
   // This creates a list of GCTasks, one per thread.
   static void create_thread_roots_tasks(GCTaskQueue* q);
   // This creates a list of GCTasks, one per thread, for marking objects.

src/share/vm/runtime/vmThread.cpp

@@ -668,8 +668,8 @@ void VMThread::execute(VM_Operation* op) {
 }
 
 
-void VMThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
-  Thread::oops_do(f, cf);
+void VMThread::oops_do(OopClosure* f, CLDToOopClosure* cld_f, CodeBlobClosure* cf) {
+  Thread::oops_do(f, cld_f, cf);
   _vm_queue->oops_do(f);
 }
 
@@ -701,5 +701,5 @@ void VMOperationQueue::verify_queue(int prio) {
 #endif
 
 void VMThread::verify() {
-  oops_do(&VerifyOopClosure::verify_oop, NULL);
+  oops_do(&VerifyOopClosure::verify_oop, NULL, NULL);
 }

src/share/vm/runtime/vmThread.hpp

@@ -137,7 +137,7 @@ class VMThread: public NamedThread {
   static VMThread* vm_thread()                    { return _vm_thread; }
 
   // GC support
-  void oops_do(OopClosure* f, CodeBlobClosure* cf);
+  void oops_do(OopClosure* f, CLDToOopClosure* cld_f, CodeBlobClosure* cf);
 
   // Debugging
   void print_on(outputStream* st) const;

test/runtime/8003720/Asmator.java

+import com.sun.xml.internal.ws.org.objectweb.asm.*;
+
+class Asmator {
+    static byte[] fixup(byte[] buf) throws java.io.IOException {
+        ClassReader cr = new ClassReader(buf);
+        ClassWriter cw = new ClassWriter(0) {
+            public MethodVisitor visitMethod(
+                final int access,
+                final String name,
+                final String desc,
+                final String signature,
+                final String[] exceptions)
+            {
+                MethodVisitor mv = super.visitMethod(access,
+                        name,
+                        desc,
+                        signature,
+                        exceptions);
+                if (mv == null)  return null;
+                if (name.equals("callme")) {
+                    // make receiver go dead!
+                    mv.visitInsn(Opcodes.ACONST_NULL);
+                    mv.visitVarInsn(Opcodes.ASTORE, 0);
+                }
+                return mv;
+            }
+        };
+        cr.accept(cw, 0);
+        return cw.toByteArray();
+    }
+}

test/runtime/8003720/Test8003720.java

+/*
+ * Copyright (c) 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.
+ *
+ */
+
+/*
+ * @test
+ * @bug 8003720
+ * @summary Method in interpreter stack frame can be deallocated
+ * @compile -XDignore.symbol.file Victim.java
+ * @run main/othervm -Xverify:all -Xint Test8003720
+ */
+
+// Attempts to make the JVM unload a class while still executing one of its methods.
+public class Test8003720 {
+    final static String VICTIM_CLASS_NAME = "Victim";
+    final static boolean QUIET = true;
+    final static long DURATION = 30000;
+
+    public interface CallMe { void callme(); }
+
+    public static void main(String... av) throws Throwable {
+        newVictimClassLoader();
+        System.gc();
+
+        newVictimClass();
+        System.gc();
+
+        newVictimInstance();
+        System.gc();
+
+        ((CallMe)newVictimInstance()).callme();
+    }
+
+    public static Object newVictimInstance() throws Throwable {
+        return newVictimClass().newInstance();
+    }
+
+    public static Class<?> newVictimClass() throws Throwable {
+        return Class.forName(VICTIM_CLASS_NAME, true, new VictimClassLoader());
+    }
+
+    public static ClassLoader newVictimClassLoader() throws Throwable {
+        return new VictimClassLoader();
+    }
+
+    public static void println(String line) {
+        if (!QUIET) {
+            System.out.println(line);
+        }
+    }
+}

test/runtime/8003720/Victim.java

+/*
+ * Copyright (c) 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.
+ *
+ */
+
+public class Victim implements Test8003720.CallMe {
+    public void callme() {
+        // note: Victim.this is dead here
+        Test8003720.println("executing in loader=" + Victim.class.getClassLoader());
+
+        long now = System.currentTimeMillis();
+
+        while ((System.currentTimeMillis() - now) < Test8003720.DURATION) {
+            long count = VictimClassLoader.counter++;
+            if (count %  1000000 == 0)  System.gc();
+            if (count % 16180000 == 0)  blurb();
+            new Object[1].clone();
+        }
+    }
+    static void blurb() {
+        Test8003720.println("count=" + VictimClassLoader.counter);
+    }
+    static {
+        blather();
+    }
+    static void blather() {
+        new java.util.ArrayList<Object>(1000000);
+        Class<Victim> c = Victim.class;
+        Test8003720.println("initializing " + c + "#" + System.identityHashCode(c) + " in " + c.getClassLoader());
+    }
+}

test/runtime/8003720/VictimClassLoader.java

+/*
+ * Copyright (c) 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.
+ *
+ */
+
+public class VictimClassLoader extends ClassLoader {
+    public static long counter = 0;
+
+    private int which = (int) ++counter;
+
+    protected VictimClassLoader() {
+        super(VictimClassLoader.class.getClassLoader());
+    }
+
+    protected Class loadClass(String name, boolean resolve) throws ClassNotFoundException {
+        Class c;
+        if (!name.endsWith("Victim")) {
+            c = super.loadClass(name, resolve);
+            return c;
+        }
+
+        c = findLoadedClass(name);
+        if (c != null) {
+            return c;
+        }
+
+        byte[] buf = readClassFile(name);
+        c = defineClass(name, buf, 0, buf.length);
+        resolveClass(c);
+
+        if (c.getClassLoader() != this) {
+            throw new AssertionError();
+        }
+
+        Test8003720.println("loaded " + c + "#" + System.identityHashCode(c) + " in " + c.getClassLoader());
+        return c;
+    }
+
+    static byte[] readClassFile(String name) {
+        try {
+            String rname = name.substring(name.lastIndexOf('.') + 1) + ".class";
+            java.net.URL url = VictimClassLoader.class.getResource(rname);
+            Test8003720.println("found " + rname + " = " + url);
+
+            java.net.URLConnection connection = url.openConnection();
+            int contentLength = connection.getContentLength();
+            byte[] buf = readFully(connection.getInputStream(), contentLength);
+
+            return Asmator.fixup(buf);
+        } catch (java.io.IOException ex) {
+            throw new Error(ex);
+        }
+    }
+
+    static byte[] readFully(java.io.InputStream in, int len) throws java.io.IOException {
+        // Warning here:
+        return sun.misc.IOUtils.readFully(in, len, true);
+    }
+
+    public void finalize() {
+        Test8003720.println("Goodbye from " + this);
+    }
+
+    public String toString() {
+        return "VictimClassLoader#" + which;
+    }
+}