# HG changeset patch
# User rkennke
# Date 1474460140 -7200
#      Wed Sep 21 14:15:40 2016 +0200
# Node ID c5e2b030c63be385cba58799423cac209faed057
# Parent  76938ff28105c38cd975b9a6e925e83af5cce810
Pin regions that contain JNI critical regions, instead of bail-and-retry protocol.

diff --git a/make/test/JtregNative.gmk b/make/test/JtregNative.gmk
--- a/make/test/JtregNative.gmk
+++ b/make/test/JtregNative.gmk
@@ -54,6 +54,7 @@
     $(HOTSPOT_TOPDIR)/test/testlibrary/jvmti \
     $(HOTSPOT_TOPDIR)/test/compiler/jvmci/jdk.vm.ci.code.test \
     $(HOTSPOT_TOPDIR)/test/serviceability/jvmti/GetModulesInfo \
+    $(HOTSPOT_TOPDIR)/test/gc/shenandoah \
     #
 
 # Add conditional directories here when needed.
diff --git a/src/share/vm/gc/shared/collectedHeap.cpp b/src/share/vm/gc/shared/collectedHeap.cpp
--- a/src/share/vm/gc/shared/collectedHeap.cpp
+++ b/src/share/vm/gc/shared/collectedHeap.cpp
@@ -142,6 +142,14 @@
   assert_locked_or_safepoint(CodeCache_lock);
 }
 
+void CollectedHeap::enter_critical(oop o) {
+  // Defaults to no-op
+}
+
+void CollectedHeap::exit_critical(oop o) {
+  // Defaults to no-op
+}
+
 void CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
   const GCHeapSummary& heap_summary = create_heap_summary();
   gc_tracer->report_gc_heap_summary(when, heap_summary);
diff --git a/src/share/vm/gc/shared/collectedHeap.hpp b/src/share/vm/gc/shared/collectedHeap.hpp
--- a/src/share/vm/gc/shared/collectedHeap.hpp
+++ b/src/share/vm/gc/shared/collectedHeap.hpp
@@ -592,6 +592,9 @@
   virtual void register_nmethod(nmethod* nm);
   virtual void unregister_nmethod(nmethod* nm);
 
+  virtual void enter_critical(oop o);
+  virtual void exit_critical(oop o);
+
   void trace_heap_before_gc(const GCTracer* gc_tracer);
   void trace_heap_after_gc(const GCTracer* gc_tracer);
 
diff --git a/src/share/vm/gc/shenandoah/shenandoahCollectorPolicy.cpp b/src/share/vm/gc/shenandoah/shenandoahCollectorPolicy.cpp
--- a/src/share/vm/gc/shenandoah/shenandoahCollectorPolicy.cpp
+++ b/src/share/vm/gc/shenandoah/shenandoahCollectorPolicy.cpp
@@ -127,7 +127,7 @@
 
   while (i < end) {
     ShenandoahHeapRegion* region = sorted_regions->get(i++);
-    if (region->garbage() > _garbage_threshold && ! region->is_humongous()) {
+    if (region->garbage() > _garbage_threshold && ! region->is_humongous() && ! region->is_pinned()) {
       //      tty->print("choose region %d with garbage = " SIZE_FORMAT " and live = " SIZE_FORMAT " and _garbage_threshold = " SIZE_FORMAT "\n",
       //                 region->region_number(), region->garbage(), region->getLiveData(), _garbage_threshold);
 
@@ -158,7 +158,7 @@
   size_t garbage = 0;
   while (i < end && garbage < min_garbage) {
     ShenandoahHeapRegion* region = sorted_regions->get(i++);
-    if (region->garbage() > _garbage_threshold && ! region->is_humongous()) {
+    if (region->garbage() > _garbage_threshold && ! region->is_humongous() && ! region->is_pinned()) {
       collection_set->add_region(region);
       garbage += region->garbage();
       region->set_is_in_collection_set(true);
@@ -175,7 +175,8 @@
   while (i < end) {
     ShenandoahHeapRegion* region = ordered_regions->get(i++);
     if ((! region->is_in_collection_set())
-        && (! region->is_humongous())) {
+        && (! region->is_humongous())
+        && (! region->is_pinned())) {
       free_set->add_region(region);
     }
   }
diff --git a/src/share/vm/gc/shenandoah/shenandoahConcurrentThread.cpp b/src/share/vm/gc/shenandoah/shenandoahConcurrentThread.cpp
--- a/src/share/vm/gc/shenandoah/shenandoahConcurrentThread.cpp
+++ b/src/share/vm/gc/shenandoah/shenandoahConcurrentThread.cpp
@@ -25,7 +25,6 @@
 #include "gc/shenandoah/shenandoahConcurrentThread.hpp"
 #include "gc/shenandoah/shenandoahCollectorPolicy.hpp"
 #include "gc/shenandoah/shenandoahHeap.inline.hpp"
-#include "gc/shenandoah/shenandoahJNICritical.hpp"
 #include "gc/shenandoah/shenandoahMonitoringSupport.hpp"
 #include "gc/shenandoah/vm_operations_shenandoah.hpp"
 #include "memory/iterator.hpp"
@@ -66,7 +65,7 @@
         TraceCollectorStats tcs(heap->monitoring_support()->full_collection_counters());
         TraceMemoryManagerStats tmms(true, _full_gc_cause);
         VM_ShenandoahFullGC full_gc(_full_gc_cause);
-        heap->jni_critical()->execute_in_vm_thread(&full_gc);
+        VMThread::execute(&full_gc);
       }
       MonitorLockerEx ml(&_full_gc_lock);
       _do_full_gc = false;
@@ -103,7 +102,7 @@
           TraceCollectorStats tcs(heap->monitoring_support()->stw_collection_counters());
           VM_ShenandoahStartEvacuation finishMark;
           heap->shenandoahPolicy()->record_phase_start(ShenandoahCollectorPolicy::final_mark_gross);
-          heap->jni_critical()->execute_in_vm_thread(&finishMark);
+          VMThread::execute(&finishMark);
           heap->shenandoahPolicy()->record_phase_end(ShenandoahCollectorPolicy::final_mark_gross);
         }
 
diff --git a/src/share/vm/gc/shenandoah/shenandoahHeap.cpp b/src/share/vm/gc/shenandoah/shenandoahHeap.cpp
--- a/src/share/vm/gc/shenandoah/shenandoahHeap.cpp
+++ b/src/share/vm/gc/shenandoah/shenandoahHeap.cpp
@@ -39,7 +39,6 @@
 #include "gc/shenandoah/shenandoahHeapRegion.hpp"
 #include "gc/shenandoah/shenandoahHeapRegionSet.hpp"
 #include "gc/shenandoah/shenandoahHumongous.hpp"
-#include "gc/shenandoah/shenandoahJNICritical.hpp"
 #include "gc/shenandoah/shenandoahMarkCompact.hpp"
 #include "gc/shenandoah/shenandoahMonitoringSupport.hpp"
 #include "gc/shenandoah/shenandoahRootProcessor.hpp"
@@ -212,7 +211,6 @@
   _need_update_refs(false),
   _need_reset_bitmaps(false),
   _growing_heap(0),
-  _jni_critical(new ShenandoahJNICritical()),
   _gc_timer(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer())
 
 {
@@ -1414,6 +1412,7 @@
 }
 
 void ShenandoahHeap::collect(GCCause::Cause cause) {
+  assert(cause != GCCause::_gc_locker, "no JNI critical callback");
   if (GCCause::is_user_requested_gc(cause)) {
     if (! DisableExplicitGC) {
       cancel_concgc();
@@ -1425,13 +1424,6 @@
     collector_policy()->set_should_clear_all_soft_refs(true);
       _concurrent_gc_thread->do_full_gc(cause);
 
-  } else if (cause == GCCause::_gc_locker) {
-
-    if (ShenandoahTraceJNICritical) {
-      tty->print_cr("Resuming deferred evacuation after JNI critical regions");
-    }
-
-    jni_critical()->notify_jni_critical();
   }
 }
 
@@ -2086,10 +2078,6 @@
   _need_update_refs = need_update_refs;
 }
 
-ShenandoahJNICritical* ShenandoahHeap::jni_critical() {
-  return _jni_critical;
-}
-
 //fixme this should be in heapregionset
 ShenandoahHeapRegion* ShenandoahHeap::next_compaction_region(const ShenandoahHeapRegion* r) {
   size_t region_idx = r->region_number() + 1;
@@ -2221,6 +2209,15 @@
 void ShenandoahHeap::unregister_nmethod(nmethod* nm) {
 }
 
+void ShenandoahHeap::enter_critical(oop o) {
+  heap_region_containing(o)->enter_critical();
+}
+
+void ShenandoahHeap::exit_critical(oop o) {
+  heap_region_containing(o)->exit_critical();
+}
+
+
 GCTimer* ShenandoahHeap::gc_timer() const {
   return _gc_timer;
 }
diff --git a/src/share/vm/gc/shenandoah/shenandoahHeap.hpp b/src/share/vm/gc/shenandoah/shenandoahHeap.hpp
--- a/src/share/vm/gc/shenandoah/shenandoahHeap.hpp
+++ b/src/share/vm/gc/shenandoah/shenandoahHeap.hpp
@@ -37,7 +37,6 @@
 class ShenandoahConcurrentMark;
 class ShenandoahConcurrentThread;
 class ShenandoahMonitoringSupport;
-class ShenandoahJNICritical;
 
 class ShenandoahAlwaysTrueClosure : public BoolObjectClosure {
 public:
@@ -127,8 +126,6 @@
 
   bool _cancelled_concgc;
 
-  ShenandoahJNICritical* _jni_critical;
-
   jbyte _growing_heap;
 
   size_t _bytes_allocated_since_cm;
@@ -215,6 +212,8 @@
   void register_nmethod(nmethod* nm);
   void unregister_nmethod(nmethod* nm);
 
+  void enter_critical(oop o);
+  void exit_critical(oop o);
 
   static ShenandoahHeap* heap();
   static ShenandoahHeap* heap_no_check();
@@ -299,7 +298,6 @@
   VirtualSpace* storage() const;
 
   ShenandoahMonitoringSupport* monitoring_support();
-  ShenandoahJNICritical* jni_critical();
   ShenandoahConcurrentMark* concurrentMark() { return _scm;}
 
   ReferenceProcessor* ref_processor() { return _ref_processor;}
diff --git a/src/share/vm/gc/shenandoah/shenandoahHeapRegion.cpp b/src/share/vm/gc/shenandoah/shenandoahHeapRegion.cpp
--- a/src/share/vm/gc/shenandoah/shenandoahHeapRegion.cpp
+++ b/src/share/vm/gc/shenandoah/shenandoahHeapRegion.cpp
@@ -419,3 +419,18 @@
 void ShenandoahHeapRegion::set_top_prev_mark_bitmap(HeapWord* top) {
   _top_prev_mark_bitmap = top;
 }
+
+void ShenandoahHeapRegion::enter_critical() {
+  assert(_critical_pins >= 0, "sanity");
+  Atomic::inc(&_critical_pins);
+}
+
+void ShenandoahHeapRegion::exit_critical() {
+  Atomic::dec(&_critical_pins);
+  assert(_critical_pins >= 0, "sanity");
+}
+
+bool ShenandoahHeapRegion::is_pinned() {
+  assert(_critical_pins >= 0, "sanity");
+  return _critical_pins > 0;
+}
diff --git a/src/share/vm/gc/shenandoah/shenandoahHeapRegion.hpp b/src/share/vm/gc/shenandoah/shenandoahHeapRegion.hpp
--- a/src/share/vm/gc/shenandoah/shenandoahHeapRegion.hpp
+++ b/src/share/vm/gc/shenandoah/shenandoahHeapRegion.hpp
@@ -51,6 +51,8 @@
 
   HeapWord* _new_top;
 
+  jint _critical_pins;
+
 #ifdef ASSERT
   int _mem_protection_level;
 #endif
@@ -138,6 +140,11 @@
   void set_new_top(HeapWord* new_top) { _new_top = new_top; }
   HeapWord* new_top() const { return _new_top; }
 
+  void enter_critical();
+  void exit_critical();
+
+  bool is_pinned();
+
 private:
   void do_reset();
 
diff --git a/src/share/vm/gc/shenandoah/shenandoahJNICritical.cpp b/src/share/vm/gc/shenandoah/shenandoahJNICritical.cpp
deleted file mode 100644
--- a/src/share/vm/gc/shenandoah/shenandoahJNICritical.cpp
+++ /dev/null
@@ -1,176 +0,0 @@
-/*
- * Copyright (c) 2015, Red Hat, Inc. and/or its affiliates.
- *
- * 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 "gc/shenandoah/shenandoahJNICritical.hpp"
-#include "gc/shenandoah/shenandoahHeap.hpp"
-
-#include "gc/shared/gcLocker.hpp"
-#include "runtime/mutexLocker.hpp"
-#include "runtime/thread.hpp"
-#include "runtime/vmThread.hpp"
-
-class VM_ShenandoahJNICriticalOperation : public VM_Operation {
-private:
-  VM_Operation* _target;
-public:
-  VM_ShenandoahJNICriticalOperation(VM_Operation* target);
-  VMOp_Type type() const;
-  bool doit_prologue();
-  void doit_epilogue();
-  void doit();
-  const char* name() const;
-};
-
-ShenandoahJNICritical::ShenandoahJNICritical() :
-  _lock(Mutex::leaf, "ShenandoahJNICritical_lock", true, Monitor::_safepoint_check_sometimes),
-  _op_waiting_for_jni_critical(NULL),
-  _op_ready_for_execution(NULL)
-{
-}
-
-/*
- * This is called by the Java thread who leaves the last JNI critical block.
- */
-void ShenandoahJNICritical::notify_jni_critical() {
-  assert(Thread::current()->is_Java_thread(), "call only from Java thread");
-
-  assert(_op_waiting_for_jni_critical != NULL, "must be waiting for jni critical notification");
-
-  if (ShenandoahTraceJNICritical) {
-    tty->print_cr("Shenandoah JNI critical: waiting until task is ready for re-execution");
-  }
-
-  {
-    MonitorLockerEx ml(&_lock);
-    while (_op_ready_for_execution == NULL) {
-      ml.wait();
-    }
-  }
-
-  assert(_op_waiting_for_jni_critical != NULL, "must be waiting for jni critical notification");
-  assert(_op_ready_for_execution != NULL, "must be ready for re-execution");
-
-  if (ShenandoahTraceJNICritical) {
-    tty->print_cr("Shenandoah JNI critical: re-executing VM task after JNI critical notification");
-  }
-
-  VMThread::execute(_op_ready_for_execution);
-
-  {
-    MonitorLockerEx ml(&_lock, Mutex::_no_safepoint_check_flag);
-    _op_waiting_for_jni_critical = NULL;
-    _op_ready_for_execution = NULL;
-    ml.notify();
-  }
-
-  if (ShenandoahTraceJNICritical) {
-    tty->print_cr("Shenandoah JNI critical: resuming Java thread after VM task re-execution");
-  }
-
-}
-
-/*
- * This is called by the VM thread, if it determines that the task must wait
- * for JNI critical regions to be left.
- */
-void ShenandoahJNICritical::set_waiting_for_jni_before_gc(VM_Operation* op) {
-  assert(Thread::current()->is_VM_thread(), "call only from VM thread");
-  _op_waiting_for_jni_critical = op;
-}
-
-/**
- * This is called by the Shenandoah concurrent thread in order
- * to execute a VM_Operation on the VM thread, that needs to perform
- * a JNI critical region check.
- */
-void ShenandoahJNICritical::execute_in_vm_thread(VM_Operation* op) {
-  assert(_op_waiting_for_jni_critical == NULL, "start out with no waiting op");
-  assert(_op_ready_for_execution == NULL, "start out with no ready op");
-  VM_ShenandoahJNICriticalOperation jni_op(op);
-  VMThread::execute(&jni_op);
-
-  {
-    MonitorLockerEx ml(&_lock, Mutex::_no_safepoint_check_flag);
-
-    if (_op_waiting_for_jni_critical != NULL) {
-      if (ShenandoahTraceJNICritical) {
-        tty->print_cr("Shenandoah JNI critical: make task ready for re-execution");
-      }
-
-      _op_ready_for_execution = _op_waiting_for_jni_critical;
-      ml.notify();
-
-      if (ShenandoahTraceJNICritical) {
-        tty->print_cr("Shenandoah JNI critical: waiting for task to get re-executed");
-      }
-
-      while (_op_ready_for_execution != NULL) {
-        ml.wait(Mutex::_no_safepoint_check_flag);
-      }
-
-      if (ShenandoahTraceJNICritical) {
-        tty->print_cr("Shenandoah JNI critical: resuming concurrent GC thread after task has been re-executed");
-      }
-    }
-  }
-
-  assert(_op_waiting_for_jni_critical == NULL, "finish with no waiting op");
-  assert(_op_ready_for_execution == NULL, "finish with no ready op");
-}
-
-
-VM_ShenandoahJNICriticalOperation::VM_ShenandoahJNICriticalOperation(VM_Operation* target)
-  : _target(target) {
-}
-
-VM_Operation::VMOp_Type VM_ShenandoahJNICriticalOperation::type() const {
-  return _target->type();
-}
-
-const char* VM_ShenandoahJNICriticalOperation::name() const {
-  return _target->name();
-}
-
-bool VM_ShenandoahJNICriticalOperation::doit_prologue() {
-  return _target->doit_prologue();
-}
-
-void VM_ShenandoahJNICriticalOperation::doit_epilogue() {
-  _target->doit_epilogue();
-}
-
-void VM_ShenandoahJNICriticalOperation::doit() {
-  if (! GCLocker::check_active_before_gc()) {
-    _target->doit();
-  } else {
-
-    if (ShenandoahTraceJNICritical) {
-      tty->print_cr("Shenandoah JNI critical: Deferring JNI critical op because of active JNI critical regions");
-    }
-
-    // This makes the GC background thread wait, and kick off evacuation as
-    // soon as JNI notifies us that critical regions have all been left.
-    ShenandoahHeap *sh = ShenandoahHeap::heap();
-    sh->jni_critical()->set_waiting_for_jni_before_gc(this);
-  }
-}
diff --git a/src/share/vm/gc/shenandoah/shenandoahJNICritical.hpp b/src/share/vm/gc/shenandoah/shenandoahJNICritical.hpp
deleted file mode 100644
--- a/src/share/vm/gc/shenandoah/shenandoahJNICritical.hpp
+++ /dev/null
@@ -1,43 +0,0 @@
-/*
- * Copyright (c) 2015, Red Hat, Inc. and/or its affiliates.
- *
- * 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_SHENANDOAH_SHENANDOAHJNICRITICAL_HPP
-#define SHARE_VM_GC_SHENANDOAH_SHENANDOAHJNICRITICAL_HPP
-
-#include "gc/shared/vmGCOperations.hpp"
-#include "memory/allocation.hpp"
-
-class ShenandoahJNICritical : public CHeapObj<mtGC> {
-private:
-  Monitor _lock;
-  VM_Operation* _op_waiting_for_jni_critical;
-  VM_Operation* _op_ready_for_execution;
-public:
-  ShenandoahJNICritical();
-  void notify_jni_critical();
-  void set_waiting_for_jni_before_gc(VM_Operation* op);
-  void execute_in_vm_thread(VM_Operation* op);
-};
-
-
-#endif // SHARE_VM_GC_SHENANDOAH_SHENANDOAHJNICRITICAL_HPP
diff --git a/src/share/vm/gc/shenandoah/shenandoahMarkCompact.cpp b/src/share/vm/gc/shenandoah/shenandoahMarkCompact.cpp
--- a/src/share/vm/gc/shenandoah/shenandoahMarkCompact.cpp
+++ b/src/share/vm/gc/shenandoah/shenandoahMarkCompact.cpp
@@ -357,12 +357,13 @@
 
   ShenandoahHeapRegion* next_from_region(ShenandoahHeapRegionSet* copy_queue) {
     ShenandoahHeapRegion* from_region = _from_regions->claim_next();
-    while (from_region != NULL && from_region->is_humongous()) {
+    while (from_region != NULL && (from_region->is_humongous() || from_region->is_pinned())) {
       from_region = _from_regions->claim_next();
     }
     if (from_region != NULL) {
       assert(copy_queue != NULL, "sanity");
       assert(! from_region->is_humongous(), "must not get humongous regions here");
+      assert(! from_region->is_pinned(), "no pinned region in mark-compact");
       copy_queue->add_region(from_region);
     }
     return from_region;
diff --git a/src/share/vm/gc/shenandoah/shenandoah_globals.hpp b/src/share/vm/gc/shenandoah/shenandoah_globals.hpp
--- a/src/share/vm/gc/shenandoah/shenandoah_globals.hpp
+++ b/src/share/vm/gc/shenandoah/shenandoah_globals.hpp
@@ -57,9 +57,6 @@
   develop(bool, ShenandoahDumpHeapAfterConcurrentMark, false,               \
           "Dump the ShenanodahHeap After Each Concurrent Mark")             \
                                                                             \
-  develop(bool, ShenandoahTraceJNICritical, false,                          \
-          "Trace Shenandoah stalls for JNI critical regions")               \
-                                                                            \
   product(bool, ShenandoahTraceHumongous, false,                            \
           "Trace Shenandoah humongous objects")                             \
                                                                             \
diff --git a/src/share/vm/gc/shenandoah/vm_operations_shenandoah.cpp b/src/share/vm/gc/shenandoah/vm_operations_shenandoah.cpp
--- a/src/share/vm/gc/shenandoah/vm_operations_shenandoah.cpp
+++ b/src/share/vm/gc/shenandoah/vm_operations_shenandoah.cpp
@@ -90,8 +90,7 @@
 
 void VM_ShenandoahStartEvacuation::doit() {
 
-  // We need to do the finish mark here, so that a JNI critical region
-  // can't divide it from evacuation start. It is critical that we
+  // It is critical that we
   // evacuate roots right after finishing marking, so that we don't
   // get unmarked objects in the roots.
   ShenandoahHeap *sh = ShenandoahHeap::heap();
diff --git a/src/share/vm/prims/jni.cpp b/src/share/vm/prims/jni.cpp
--- a/src/share/vm/prims/jni.cpp
+++ b/src/share/vm/prims/jni.cpp
@@ -3184,6 +3184,7 @@
   }
   oop a = JNIHandles::resolve_non_null(array);
   a = oopDesc::bs()->write_barrier(a);
+  Universe::heap()->enter_critical(a);
   assert(a->is_array(), "just checking");
   BasicType type;
   if (a->is_objArray()) {
@@ -3201,6 +3202,21 @@
   JNIWrapper("ReleasePrimitiveArrayCritical");
   HOTSPOT_JNI_RELEASEPRIMITIVEARRAYCRITICAL_ENTRY(env, array, carray, mode);
   // The array, carray and mode arguments are ignored
+  oop a = JNIHandles::resolve_non_null(array);
+  a = oopDesc::bs()->read_barrier(a);
+#ifdef ASSERT
+  assert(a->is_array(), "just checking");
+  BasicType type;
+  if (a->is_objArray()) {
+    type = T_OBJECT;
+  } else {
+    type = TypeArrayKlass::cast(a->klass())->element_type();
+  }
+  void* ret = arrayOop(a)->base(type);
+  assert(ret == carray, "check array not moved");
+#endif
+
+  Universe::heap()->exit_critical(a);
   GCLocker::unlock_critical(thread);
 HOTSPOT_JNI_RELEASEPRIMITIVEARRAYCRITICAL_RETURN();
 JNI_END
@@ -3211,6 +3227,8 @@
   HOTSPOT_JNI_GETSTRINGCRITICAL_ENTRY(env, string, (uintptr_t *) isCopy);
   GCLocker::lock_critical(thread);
   oop s = JNIHandles::resolve_non_null(string);
+  s = oopDesc::bs()->write_barrier(s);
+  Universe::heap()->enter_critical(s);
   typeArrayOop s_value = java_lang_String::value(s);
   bool is_latin1 = java_lang_String::is_latin1(s);
   if (isCopy != NULL) {
@@ -3241,6 +3259,8 @@
   HOTSPOT_JNI_RELEASESTRINGCRITICAL_ENTRY(env, str, (uint16_t *) chars);
   // The str and chars arguments are ignored for UTF16 strings
   oop s = JNIHandles::resolve_non_null(str);
+  s = oopDesc::bs()->read_barrier(s);
+  Universe::heap()->exit_critical(s);
   bool is_latin1 = java_lang_String::is_latin1(s);
   if (is_latin1) {
     // For latin1 string, free jchar array allocated by earlier call to GetStringCritical.
diff --git a/test/TEST.groups b/test/TEST.groups
--- a/test/TEST.groups
+++ b/test/TEST.groups
@@ -331,6 +331,9 @@
 hotspot_fast_compiler_closed = \
   sanity/ExecuteInternalVMTests.java
 
+hotspot_fast_gc_shenandoah = \
+  gc/shenandoah/
+
 hotspot_fast_gc_1 = \
   gc/g1/
 
diff --git a/test/gc/shenandoah/ShenandoahJNICritical.java b/test/gc/shenandoah/ShenandoahJNICritical.java
new file mode 100644
--- /dev/null
+++ b/test/gc/shenandoah/ShenandoahJNICritical.java
@@ -0,0 +1,67 @@
+/*
+ * Copyright (c) 2016 Red Hat, Inc. and/or its affiliates.
+ *
+ * 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
+ * @summary test JNI critical arrays support in Shenandoah
+ * @run main/othervm/native -XX:+UseShenandoahGC -XX:ShenandoahGCHeuristics=aggressive ShenandoahJNICritical
+ */
+
+import java.util.Arrays;
+
+public class ShenandoahJNICritical {
+    static {
+        System.loadLibrary("ShenandoahJNICritical");
+    }
+
+    private static final int NUM_RUNS = 10000;
+    private static final int ARRAY_SIZE=10000;
+    private static int[] a;
+    private static int[] b;
+    private static native void copyAtoB(int[] a, int[] b);
+
+    public static void main(String[] args) {
+        a = new int[ARRAY_SIZE];
+        b = new int[ARRAY_SIZE];
+        for (int i = 0; i < NUM_RUNS; i++) {
+            test();
+        }
+    }
+
+    private static void test() {
+        int[] a1 = new int[ARRAY_SIZE];
+        int[] b1 = new int[ARRAY_SIZE];
+        fillArray(a);
+        copyAtoB(a, b);
+        copyAtoB(a1, b1); // Don't optimize out garbage arrays.
+        if (! Arrays.equals(a, b)) {
+            throw new RuntimeException("arrays not equal");
+        }
+    }
+
+    private static void fillArray(int[] array) {
+        for (int i = 0; i < ARRAY_SIZE; i++) {
+            int val = (int) (Math.random() * Integer.MAX_VALUE);
+            array[i] = val;
+        }
+    }
+}
diff --git a/test/gc/shenandoah/libShenandoahJNICritical.c b/test/gc/shenandoah/libShenandoahJNICritical.c
new file mode 100644
--- /dev/null
+++ b/test/gc/shenandoah/libShenandoahJNICritical.c
@@ -0,0 +1,35 @@
+/*
+ * Copyright (c) 2016 Red Hat, Inc. and/or its affiliates.
+ *
+ * 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 <jni.h>
+#include <string.h>
+
+JNIEXPORT void JNICALL
+Java_ShenandoahJNICritical_copyAtoB(JNIEnv *env, jclass unused, jintArray a, jintArray b) {
+  jint len = (*env)->GetArrayLength(env, a);
+  jint* aa = (*env)->GetPrimitiveArrayCritical(env, a, 0);
+  jint* bb = (*env)->GetPrimitiveArrayCritical(env, b, 0);
+  memcpy(bb, aa, len * sizeof(jint));
+  (*env)->ReleasePrimitiveArrayCritical(env, b, bb, 0);
+  (*env)->ReleasePrimitiveArrayCritical(env, a, aa, 0);
+}