Merge "Revert^2 "Implement LockSupport.park with a futex""

7 files changed, 238 insertions, 34 deletions

diff --git a/runtime/native/sun_misc_Unsafe.cc b/runtime/native/sun_misc_Unsafe.cc
index e021b77dae..a739c2d16e 100644
--- a/runtime/native/sun_misc_Unsafe.cc
+++ b/runtime/native/sun_misc_Unsafe.cc
@@ -31,8 +31,10 @@
 #include "mirror/array.h"
 #include "mirror/class-inl.h"
 #include "mirror/object-inl.h"
+#include "art_field-inl.h"
 #include "native_util.h"
 #include "scoped_fast_native_object_access-inl.h"
+#include "well_known_classes.h"
 
 namespace art {
 
@@ -504,6 +506,33 @@ static void Unsafe_fullFence(JNIEnv*, jobject) {
   std::atomic_thread_fence(std::memory_order_seq_cst);
 }
 
+static void Unsafe_park(JNIEnv* env, jobject, jboolean isAbsolute, jlong time) {
+  ScopedObjectAccess soa(env);
+  Thread::Current()->Park(isAbsolute, time);
+}
+
+static void Unsafe_unpark(JNIEnv* env, jobject, jobject jthread) {
+  art::ScopedFastNativeObjectAccess soa(env);
+  if (jthread == nullptr || !env->IsInstanceOf(jthread, WellKnownClasses::java_lang_Thread)) {
+    ThrowIllegalArgumentException("Argument to unpark() was not a Thread");
+    return;
+  }
+  art::MutexLock mu(soa.Self(), *art::Locks::thread_list_lock_);
+  art::Thread* thread = art::Thread::FromManagedThread(soa, jthread);
+  if (thread != nullptr) {
+    thread->Unpark();
+  } else {
+    // If thread is null, that means that either the thread is not started yet,
+    // or the thread has already terminated. Setting the field to true will be
+    // respected when the thread does start, and is harmless if the thread has
+    // already terminated.
+    ArtField* unparked =
+        jni::DecodeArtField(WellKnownClasses::java_lang_Thread_unparkedBeforeStart);
+    // JNI must use non transactional mode.
+    unparked->SetBoolean<false>(soa.Decode<mirror::Object>(jthread), JNI_TRUE);
+  }
+}
+
 static JNINativeMethod gMethods[] = {
   FAST_NATIVE_METHOD(Unsafe, compareAndSwapInt, "(Ljava/lang/Object;JII)Z"),
   FAST_NATIVE_METHOD(Unsafe, compareAndSwapLong, "(Ljava/lang/Object;JJJ)Z"),
@@ -546,6 +575,8 @@ static JNINativeMethod gMethods[] = {
   FAST_NATIVE_METHOD(Unsafe, putShort, "(Ljava/lang/Object;JS)V"),
   FAST_NATIVE_METHOD(Unsafe, putFloat, "(Ljava/lang/Object;JF)V"),
   FAST_NATIVE_METHOD(Unsafe, putDouble, "(Ljava/lang/Object;JD)V"),
+  FAST_NATIVE_METHOD(Unsafe, unpark, "(Ljava/lang/Object;)V"),
+  NATIVE_METHOD(Unsafe, park, "(ZJ)V"),
 
   // Each of the getFoo variants are overloaded with a call that operates
   // directively on a native pointer.
diff --git a/runtime/thread.cc b/runtime/thread.cc
index b5d214def4..12ec5a99fd 100644
--- a/runtime/thread.cc
+++ b/runtime/thread.cc
@@ -44,6 +44,7 @@
 #include "arch/context.h"
 #include "art_field-inl.h"
 #include "art_method-inl.h"
+#include "base/atomic.h"
 #include "base/bit_utils.h"
 #include "base/casts.h"
 #include "base/file_utils.h"
@@ -285,6 +286,116 @@ void Thread::AssertHasDeoptimizationContext() {
       << "No deoptimization context for thread " << *this;
 }
 
+enum {
+  kPermitAvailable = 0,  // Incrementing consumes the permit
+  kNoPermit = 1,  // Incrementing marks as waiter waiting
+  kNoPermitWaiterWaiting = 2
+};
+
+void Thread::Park(bool is_absolute, int64_t time) {
+  DCHECK(this == Thread::Current());
+#if ART_USE_FUTEXES
+  // Consume the permit, or mark as waiting. This cannot cause park_state to go
+  // outside of its valid range (0, 1, 2), because in all cases where 2 is
+  // assigned it is set back to 1 before returning, and this method cannot run
+  // concurrently with itself since it operates on the current thread.
+  int old_state = tls32_.park_state_.fetch_add(1, std::memory_order_relaxed);
+  if (old_state == kNoPermit) {
+    // no permit was available. block thread until later.
+    // TODO: Call to signal jvmti here
+    int result = 0;
+    if (!is_absolute && time == 0) {
+      // Thread.getState() is documented to return waiting for untimed parks.
+      ScopedThreadSuspension sts(this, ThreadState::kWaiting);
+      DCHECK_EQ(NumberOfHeldMutexes(), 0u);
+      result = futex(tls32_.park_state_.Address(),
+                     FUTEX_WAIT_PRIVATE,
+                     /* sleep if val = */ kNoPermitWaiterWaiting,
+                     /* timeout */ nullptr,
+                     nullptr,
+                     0);
+    } else if (time > 0) {
+      // Only actually suspend and futex_wait if we're going to wait for some
+      // positive amount of time - the kernel will reject negative times with
+      // EINVAL, and a zero time will just noop.
+
+      // Thread.getState() is documented to return timed wait for timed parks.
+      ScopedThreadSuspension sts(this, ThreadState::kTimedWaiting);
+      DCHECK_EQ(NumberOfHeldMutexes(), 0u);
+      timespec timespec;
+      if (is_absolute) {
+        // Time is millis when scheduled for an absolute time
+        timespec.tv_nsec = (time % 1000) * 1000000;
+        timespec.tv_sec = time / 1000;
+        // This odd looking pattern is recommended by futex documentation to
+        // wait until an absolute deadline, with otherwise identical behavior to
+        // FUTEX_WAIT_PRIVATE. This also allows parkUntil() to return at the
+        // correct time when the system clock changes.
+        result = futex(tls32_.park_state_.Address(),
+                       FUTEX_WAIT_BITSET_PRIVATE | FUTEX_CLOCK_REALTIME,
+                       /* sleep if val = */ kNoPermitWaiterWaiting,
+                       &timespec,
+                       nullptr,
+                       FUTEX_BITSET_MATCH_ANY);
+      } else {
+        // Time is nanos when scheduled for a relative time
+        timespec.tv_sec = time / 1000000000;
+        timespec.tv_nsec = time % 1000000000;
+        result = futex(tls32_.park_state_.Address(),
+                       FUTEX_WAIT_PRIVATE,
+                       /* sleep if val = */ kNoPermitWaiterWaiting,
+                       &timespec,
+                       nullptr,
+                       0);
+      }
+    }
+    if (result == -1) {
+      switch (errno) {
+        case EAGAIN:
+        case ETIMEDOUT:
+        case EINTR: break;  // park() is allowed to spuriously return
+        default: PLOG(FATAL) << "Failed to park";
+      }
+    }
+    // Mark as no longer waiting, and consume permit if there is one.
+    tls32_.park_state_.store(kNoPermit, std::memory_order_relaxed);
+    // TODO: Call to signal jvmti here
+  } else {
+    // the fetch_add has consumed the permit. immediately return.
+    DCHECK_EQ(old_state, kPermitAvailable);
+  }
+#else
+  #pragma clang diagnostic push
+  #pragma clang diagnostic warning "-W#warnings"
+  #warning "LockSupport.park/unpark implemented as noops without FUTEX support."
+  #pragma clang diagnostic pop
+  UNUSED(is_absolute, time);
+  UNIMPLEMENTED(WARNING);
+  sched_yield();
+#endif
+}
+
+void Thread::Unpark() {
+#if ART_USE_FUTEXES
+  // Set permit available; will be consumed either by fetch_add (when the thread
+  // tries to park) or store (when the parked thread is woken up)
+  if (tls32_.park_state_.exchange(kPermitAvailable, std::memory_order_relaxed)
+      == kNoPermitWaiterWaiting) {
+    int result = futex(tls32_.park_state_.Address(),
+                       FUTEX_WAKE_PRIVATE,
+                       /* number of waiters = */ 1,
+                       nullptr,
+                       nullptr,
+                       0);
+    if (result == -1) {
+      PLOG(FATAL) << "Failed to unpark";
+    }
+  }
+#else
+  UNIMPLEMENTED(WARNING);
+#endif
+}
+
 void Thread::PushStackedShadowFrame(ShadowFrame* sf, StackedShadowFrameType type) {
   StackedShadowFrameRecord* record = new StackedShadowFrameRecord(
       sf, type, tlsPtr_.stacked_shadow_frame_record);
@@ -489,6 +600,22 @@ void* Thread::CreateCallback(void* arg) {
 
     runtime->GetRuntimeCallbacks()->ThreadStart(self);
 
+    // Unpark ourselves if the java peer was unparked before it started (see
+    // b/28845097#comment49 for more information)
+
+    ArtField* unparkedField = jni::DecodeArtField(
+        WellKnownClasses::java_lang_Thread_unparkedBeforeStart);
+    bool should_unpark = false;
+    {
+      // Hold the lock here, so that if another thread calls unpark before the thread starts
+      // we don't observe the unparkedBeforeStart field before the unparker writes to it,
+      // which could cause a lost unpark.
+      art::MutexLock mu(soa.Self(), *art::Locks::thread_list_lock_);
+      should_unpark = unparkedField->GetBoolean(self->tlsPtr_.opeer) == JNI_TRUE;
+    }
+    if (should_unpark) {
+      self->Unpark();
+    }
     // Invoke the 'run' method of our java.lang.Thread.
     ObjPtr<mirror::Object> receiver = self->tlsPtr_.opeer;
     jmethodID mid = WellKnownClasses::java_lang_Thread_run;
@@ -2133,6 +2260,9 @@ Thread::Thread(bool daemon)
   tls32_.state_and_flags.as_struct.flags = 0;
   tls32_.state_and_flags.as_struct.state = kNative;
   tls32_.interrupted.store(false, std::memory_order_relaxed);
+  // Initialize with no permit; if the java Thread was unparked before being
+  // started, it will unpark itself before calling into java code.
+  tls32_.park_state_.store(kNoPermit, std::memory_order_relaxed);
   memset(&tlsPtr_.held_mutexes[0], 0, sizeof(tlsPtr_.held_mutexes));
   std::fill(tlsPtr_.rosalloc_runs,
             tlsPtr_.rosalloc_runs + kNumRosAllocThreadLocalSizeBracketsInThread,
@@ -2449,12 +2579,15 @@ bool Thread::IsInterrupted() {
 }
 
 void Thread::Interrupt(Thread* self) {
-  MutexLock mu(self, *wait_mutex_);
-  if (tls32_.interrupted.load(std::memory_order_seq_cst)) {
-    return;
+  {
+    MutexLock mu(self, *wait_mutex_);
+    if (tls32_.interrupted.load(std::memory_order_seq_cst)) {
+      return;
+    }
+    tls32_.interrupted.store(true, std::memory_order_seq_cst);
+    NotifyLocked(self);
   }
-  tls32_.interrupted.store(true, std::memory_order_seq_cst);
-  NotifyLocked(self);
+  Unpark();
 }
 
 void Thread::Notify() {
diff --git a/runtime/thread.h b/runtime/thread.h
index 941867ce2d..b304cef74d 100644
--- a/runtime/thread.h
+++ b/runtime/thread.h
@@ -581,6 +581,11 @@ class Thread {
     return poison_object_cookie_;
   }
 
+  // Parking for 0ns of relative time means an untimed park, negative (though
+  // should be handled in java code) returns immediately
+  void Park(bool is_absolute, int64_t time) REQUIRES_SHARED(Locks::mutator_lock_);
+  void Unpark();
+
  private:
   void NotifyLocked(Thread* self) REQUIRES(wait_mutex_);
 
@@ -1543,6 +1548,8 @@ class Thread {
     // Thread "interrupted" status; stays raised until queried or thrown.
     Atomic<bool32_t> interrupted;
 
+    AtomicInteger park_state_;
+
     // True if the thread is allowed to access a weak ref (Reference::GetReferent() and system
     // weaks) and to potentially mark an object alive/gray. This is used for concurrent reference
     // processing of the CC collector only. This is thread local so that we can enable/disable weak
diff --git a/runtime/well_known_classes.cc b/runtime/well_known_classes.cc
index 206418fbc6..94faa626f6 100644
--- a/runtime/well_known_classes.cc
+++ b/runtime/well_known_classes.cc
@@ -128,6 +128,7 @@ jfieldID WellKnownClasses::java_lang_Thread_lock;
 jfieldID WellKnownClasses::java_lang_Thread_name;
 jfieldID WellKnownClasses::java_lang_Thread_priority;
 jfieldID WellKnownClasses::java_lang_Thread_nativePeer;
+jfieldID WellKnownClasses::java_lang_Thread_unparkedBeforeStart;
 jfieldID WellKnownClasses::java_lang_ThreadGroup_groups;
 jfieldID WellKnownClasses::java_lang_ThreadGroup_ngroups;
 jfieldID WellKnownClasses::java_lang_ThreadGroup_mainThreadGroup;
@@ -376,6 +377,7 @@ void WellKnownClasses::Init(JNIEnv* env) {
   java_lang_Thread_name = CacheField(env, java_lang_Thread, false, "name", "Ljava/lang/String;");
   java_lang_Thread_priority = CacheField(env, java_lang_Thread, false, "priority", "I");
   java_lang_Thread_nativePeer = CacheField(env, java_lang_Thread, false, "nativePeer", "J");
+  java_lang_Thread_unparkedBeforeStart = CacheField(env, java_lang_Thread, false, "unparkedBeforeStart", "Z");
   java_lang_ThreadGroup_groups = CacheField(env, java_lang_ThreadGroup, false, "groups", "[Ljava/lang/ThreadGroup;");
   java_lang_ThreadGroup_ngroups = CacheField(env, java_lang_ThreadGroup, false, "ngroups", "I");
   java_lang_ThreadGroup_mainThreadGroup = CacheField(env, java_lang_ThreadGroup, true, "mainThreadGroup", "Ljava/lang/ThreadGroup;");
diff --git a/runtime/well_known_classes.h b/runtime/well_known_classes.h
index ce5ab1df84..8c85228dfc 100644
--- a/runtime/well_known_classes.h
+++ b/runtime/well_known_classes.h
@@ -137,6 +137,7 @@ struct WellKnownClasses {
   static jfieldID java_lang_Thread_name;
   static jfieldID java_lang_Thread_priority;
   static jfieldID java_lang_Thread_nativePeer;
+  static jfieldID java_lang_Thread_unparkedBeforeStart;
   static jfieldID java_lang_ThreadGroup_groups;
   static jfieldID java_lang_ThreadGroup_ngroups;
   static jfieldID java_lang_ThreadGroup_mainThreadGroup;
diff --git a/test/004-ThreadStress/src-art/Main.java b/test/004-ThreadStress/src-art/Main.java
index 3a89f4f166..b8bfafb2d3 100644
--- a/test/004-ThreadStress/src-art/Main.java
+++ b/test/004-ThreadStress/src-art/Main.java
@@ -26,6 +26,7 @@ import java.util.List;
 import java.util.Map;
 import java.util.Set;
 import java.util.concurrent.Semaphore;
+import java.util.concurrent.locks.LockSupport;
 
 // Run on host with:
 //   javac ThreadTest.java && java ThreadStress && rm *.class
@@ -251,6 +252,31 @@ public class Main implements Runnable {
         }
     }
 
+    private final static class TimedPark extends Operation {
+        private final static int SLEEP_TIME = 100;
+
+        public TimedPark() {}
+
+        @Override
+        public boolean perform() {
+            LockSupport.parkNanos(this, 100*1000000);
+            return true;
+        }
+    }
+
+    private final static class UnparkAllThreads extends Operation {
+        public UnparkAllThreads() {}
+
+        @Override
+        public boolean perform() {
+            Set<Thread> threads = Thread.getAllStackTraces().keySet();
+            for (Thread candidate : threads) {
+                LockSupport.unpark(candidate);
+            }
+            return true;
+        }
+    }
+
     private final static class SyncAndWork extends Operation {
         private final Object lock;
 
@@ -320,7 +346,9 @@ public class Main implements Runnable {
         frequencyMap.put(new NonMovingAlloc(), 0.025);        //   5/200
         frequencyMap.put(new StackTrace(), 0.1);              //  20/200
         frequencyMap.put(new Exit(), 0.225);                  //  45/200
-        frequencyMap.put(new Sleep(), 0.125);                 //  25/200
+        frequencyMap.put(new Sleep(), 0.125);                 //  15/200
+        frequencyMap.put(new TimedPark(), 0.025);             //   5/200
+        frequencyMap.put(new UnparkAllThreads(), 0.025);      //   5/200
         frequencyMap.put(new TimedWait(lock), 0.05);          //  10/200
         frequencyMap.put(new Wait(lock), 0.075);              //  15/200
         frequencyMap.put(new QueuedWait(semaphore), 0.05);    //  10/200
@@ -341,9 +369,11 @@ public class Main implements Runnable {
     private final static Map<Operation, Double> createLockFrequencyMap(Object lock) {
       Map<Operation, Double> frequencyMap = new HashMap<Operation, Double>();
       frequencyMap.put(new Sleep(), 0.2);                     //  40/200
-      frequencyMap.put(new TimedWait(lock), 0.2);             //  40/200
-      frequencyMap.put(new Wait(lock), 0.2);                  //  40/200
+      frequencyMap.put(new TimedWait(lock), 0.1);             //  20/200
+      frequencyMap.put(new Wait(lock), 0.1);                  //  20/200
       frequencyMap.put(new SyncAndWork(lock), 0.4);           //  80/200
+      frequencyMap.put(new TimedPark(), 0.1);                 //  20/200
+      frequencyMap.put(new UnparkAllThreads(), 0.1);          //  20/200
 
       return frequencyMap;
     }
diff --git a/test/913-heaps/expected.txt b/test/913-heaps/expected.txt
index 065b854a6a..1bd56d1a53 100644
--- a/test/913-heaps/expected.txt
+++ b/test/913-heaps/expected.txt
@@ -1,9 +1,9 @@
 ---
 true true
-root@root --(jni-local[id=1,tag=3000,depth=0,method=followReferences])--> 3000@0 [size=132, length=-1]
+root@root --(jni-local[id=1,tag=3000,depth=0,method=followReferences])--> 3000@0 [size=124, length=-1]
 root@root --(stack-local[id=1,tag=3000,depth=2,method=doFollowReferencesTestNonRoot,vreg=8,location= 31])--> 1@1000 [size=16, length=-1]
-root@root --(stack-local[id=1,tag=3000,depth=5,method=run,vreg=2,location= 0])--> 3000@0 [size=132, length=-1]
-root@root --(thread)--> 3000@0 [size=132, length=-1]
+root@root --(stack-local[id=1,tag=3000,depth=5,method=run,vreg=2,location= 0])--> 3000@0 [size=124, length=-1]
+root@root --(thread)--> 3000@0 [size=124, length=-1]
 1001@0 --(superclass)--> 1000@0 [size=123456780000, length=-1]
 1002@0 --(interface)--> 2001@0 [size=123456780004, length=-1]
 1002@0 --(superclass)--> 1001@0 [size=123456780001, length=-1]
@@ -44,14 +44,14 @@ root@root --(thread)--> 3000@0 [size=132, length=-1]
 ---
 root@root --(jni-global)--> 1@1000 [size=16, length=-1]
 root@root --(jni-local[id=1,tag=3000,depth=0,method=followReferences])--> 1@1000 [size=16, length=-1]
-root@root --(jni-local[id=1,tag=3000,depth=0,method=followReferences])--> 3000@0 [size=132, length=-1]
+root@root --(jni-local[id=1,tag=3000,depth=0,method=followReferences])--> 3000@0 [size=124, length=-1]
 root@root --(stack-local[id=1,tag=3000,depth=1,method=doFollowReferencesTestImpl,vreg=10,location= 8])--> 1@1000 [size=16, length=-1]
 root@root --(stack-local[id=1,tag=3000,depth=1,method=doFollowReferencesTestImpl,vreg=5,location= 8])--> 1@1000 [size=16, length=-1]
 root@root --(stack-local[id=1,tag=3000,depth=2,method=doFollowReferencesTestRoot,vreg=13,location= 20])--> 1@1000 [size=16, length=-1]
 root@root --(stack-local[id=1,tag=3000,depth=2,method=doFollowReferencesTestRoot,vreg=4,location= 20])--> 1@1000 [size=16, length=-1]
-root@root --(stack-local[id=1,tag=3000,depth=5,method=run,vreg=2,location= 0])--> 3000@0 [size=132, length=-1]
+root@root --(stack-local[id=1,tag=3000,depth=5,method=run,vreg=2,location= 0])--> 3000@0 [size=124, length=-1]
 root@root --(thread)--> 1@1000 [size=16, length=-1]
-root@root --(thread)--> 3000@0 [size=132, length=-1]
+root@root --(thread)--> 3000@0 [size=124, length=-1]
 1001@0 --(superclass)--> 1000@0 [size=123456780005, length=-1]
 1002@0 --(interface)--> 2001@0 [size=123456780009, length=-1]
 1002@0 --(superclass)--> 1001@0 [size=123456780006, length=-1]
@@ -90,18 +90,18 @@ root@root --(thread)--> 3000@0 [size=132, length=-1]
 5@1002 --(field@9)--> 6@1000 [size=16, length=-1]
 6@1000 --(class)--> 1000@0 [size=123456780005, length=-1]
 ---
-root@root --(thread)--> 3000@0 [size=132, length=-1]
+root@root --(thread)--> 3000@0 [size=124, length=-1]
 ---
 3@1001 --(class)--> 1001@0 [size=123456780011, length=-1]
 ---
-root@root --(thread)--> 3000@0 [size=132, length=-1]
+root@root --(thread)--> 3000@0 [size=124, length=-1]
 ---
 3@1001 --(class)--> 1001@0 [size=123456780016, length=-1]
 ---
-root@root --(jni-local[id=1,tag=3000,depth=0,method=followReferences])--> 3000@0 [size=132, length=-1]
+root@root --(jni-local[id=1,tag=3000,depth=0,method=followReferences])--> 3000@0 [size=124, length=-1]
 root@root --(stack-local[id=1,tag=3000,depth=2,method=doFollowReferencesTestNonRoot,vreg=8,location= 31])--> 1@1000 [size=16, length=-1]
-root@root --(stack-local[id=1,tag=3000,depth=5,method=run,vreg=2,location= 0])--> 3000@0 [size=132, length=-1]
-root@root --(thread)--> 3000@0 [size=132, length=-1]
+root@root --(stack-local[id=1,tag=3000,depth=5,method=run,vreg=2,location= 0])--> 3000@0 [size=124, length=-1]
+root@root --(thread)--> 3000@0 [size=124, length=-1]
 ---
 1001@0 --(superclass)--> 1000@0 [size=123456780020, length=-1]
 3@1001 --(class)--> 1001@0 [size=123456780021, length=-1]
@@ -110,14 +110,14 @@ root@root --(thread)--> 3000@0 [size=132, length=-1]
 ---
 root@root --(jni-global)--> 1@1000 [size=16, length=-1]
 root@root --(jni-local[id=1,tag=3000,depth=0,method=followReferences])--> 1@1000 [size=16, length=-1]
-root@root --(jni-local[id=1,tag=3000,depth=0,method=followReferences])--> 3000@0 [size=132, length=-1]
+root@root --(jni-local[id=1,tag=3000,depth=0,method=followReferences])--> 3000@0 [size=124, length=-1]
 root@root --(stack-local[id=1,tag=3000,depth=1,method=doFollowReferencesTestImpl,vreg=10,location= 8])--> 1@1000 [size=16, length=-1]
 root@root --(stack-local[id=1,tag=3000,depth=1,method=doFollowReferencesTestImpl,vreg=5,location= 8])--> 1@1000 [size=16, length=-1]
 root@root --(stack-local[id=1,tag=3000,depth=2,method=doFollowReferencesTestRoot,vreg=13,location= 20])--> 1@1000 [size=16, length=-1]
 root@root --(stack-local[id=1,tag=3000,depth=2,method=doFollowReferencesTestRoot,vreg=4,location= 20])--> 1@1000 [size=16, length=-1]
-root@root --(stack-local[id=1,tag=3000,depth=5,method=run,vreg=2,location= 0])--> 3000@0 [size=132, length=-1]
+root@root --(stack-local[id=1,tag=3000,depth=5,method=run,vreg=2,location= 0])--> 3000@0 [size=124, length=-1]
 root@root --(thread)--> 1@1000 [size=16, length=-1]
-root@root --(thread)--> 3000@0 [size=132, length=-1]
+root@root --(thread)--> 3000@0 [size=124, length=-1]
 ---
 1001@0 --(superclass)--> 1000@0 [size=123456780025, length=-1]
 3@1001 --(class)--> 1001@0 [size=123456780026, length=-1]
@@ -198,10 +198,10 @@ root@root --(thread)--> 1@1000 [size=16, length=-1]
 ---
 ---
 ---- untagged objects
-root@root --(jni-local[id=1,tag=3000,depth=0,method=followReferences])--> 3000@0 [size=132, length=-1]
+root@root --(jni-local[id=1,tag=3000,depth=0,method=followReferences])--> 3000@0 [size=124, length=-1]
 root@root --(stack-local[id=1,tag=3000,depth=2,method=doFollowReferencesTestNonRoot,vreg=8,location= 31])--> 1@1000 [size=16, length=-1]
-root@root --(stack-local[id=1,tag=3000,depth=5,method=run,vreg=2,location= 0])--> 3000@0 [size=132, length=-1]
-root@root --(thread)--> 3000@0 [size=132, length=-1]
+root@root --(stack-local[id=1,tag=3000,depth=5,method=run,vreg=2,location= 0])--> 3000@0 [size=124, length=-1]
+root@root --(thread)--> 3000@0 [size=124, length=-1]
 1001@0 --(superclass)--> 1000@0 [size=123456780050, length=-1]
 1002@0 --(interface)--> 2001@0 [size=123456780054, length=-1]
 1002@0 --(superclass)--> 1001@0 [size=123456780051, length=-1]
@@ -242,14 +242,14 @@ root@root --(thread)--> 3000@0 [size=132, length=-1]
 ---
 root@root --(jni-global)--> 1@1000 [size=16, length=-1]
 root@root --(jni-local[id=1,tag=3000,depth=0,method=followReferences])--> 1@1000 [size=16, length=-1]
-root@root --(jni-local[id=1,tag=3000,depth=0,method=followReferences])--> 3000@0 [size=132, length=-1]
+root@root --(jni-local[id=1,tag=3000,depth=0,method=followReferences])--> 3000@0 [size=124, length=-1]
 root@root --(stack-local[id=1,tag=3000,depth=1,method=doFollowReferencesTestImpl,vreg=10,location= 8])--> 1@1000 [size=16, length=-1]
 root@root --(stack-local[id=1,tag=3000,depth=1,method=doFollowReferencesTestImpl,vreg=5,location= 8])--> 1@1000 [size=16, length=-1]
 root@root --(stack-local[id=1,tag=3000,depth=2,method=doFollowReferencesTestRoot,vreg=13,location= 20])--> 1@1000 [size=16, length=-1]
 root@root --(stack-local[id=1,tag=3000,depth=2,method=doFollowReferencesTestRoot,vreg=4,location= 20])--> 1@1000 [size=16, length=-1]
-root@root --(stack-local[id=1,tag=3000,depth=5,method=run,vreg=2,location= 0])--> 3000@0 [size=132, length=-1]
+root@root --(stack-local[id=1,tag=3000,depth=5,method=run,vreg=2,location= 0])--> 3000@0 [size=124, length=-1]
 root@root --(thread)--> 1@1000 [size=16, length=-1]
-root@root --(thread)--> 3000@0 [size=132, length=-1]
+root@root --(thread)--> 3000@0 [size=124, length=-1]
 1001@0 --(superclass)--> 1000@0 [size=123456780055, length=-1]
 1002@0 --(interface)--> 2001@0 [size=123456780059, length=-1]
 1002@0 --(superclass)--> 1001@0 [size=123456780056, length=-1]
@@ -289,9 +289,9 @@ root@root --(thread)--> 3000@0 [size=132, length=-1]
 6@1000 --(class)--> 1000@0 [size=123456780055, length=-1]
 ---
 ---- tagged classes
-root@root --(jni-local[id=1,tag=3000,depth=0,method=followReferences])--> 3000@0 [size=132, length=-1]
-root@root --(stack-local[id=1,tag=3000,depth=5,method=run,vreg=2,location= 0])--> 3000@0 [size=132, length=-1]
-root@root --(thread)--> 3000@0 [size=132, length=-1]
+root@root --(jni-local[id=1,tag=3000,depth=0,method=followReferences])--> 3000@0 [size=124, length=-1]
+root@root --(stack-local[id=1,tag=3000,depth=5,method=run,vreg=2,location= 0])--> 3000@0 [size=124, length=-1]
+root@root --(thread)--> 3000@0 [size=124, length=-1]
 1001@0 --(superclass)--> 1000@0 [size=123456780060, length=-1]
 1002@0 --(interface)--> 2001@0 [size=123456780064, length=-1]
 1002@0 --(superclass)--> 1001@0 [size=123456780061, length=-1]
@@ -316,9 +316,9 @@ root@root --(thread)--> 3000@0 [size=132, length=-1]
 5@1002 --(field@8)--> 500@0 [size=20, length=2]
 6@1000 --(class)--> 1000@0 [size=123456780060, length=-1]
 ---
-root@root --(jni-local[id=1,tag=3000,depth=0,method=followReferences])--> 3000@0 [size=132, length=-1]
-root@root --(stack-local[id=1,tag=3000,depth=5,method=run,vreg=2,location= 0])--> 3000@0 [size=132, length=-1]
-root@root --(thread)--> 3000@0 [size=132, length=-1]
+root@root --(jni-local[id=1,tag=3000,depth=0,method=followReferences])--> 3000@0 [size=124, length=-1]
+root@root --(stack-local[id=1,tag=3000,depth=5,method=run,vreg=2,location= 0])--> 3000@0 [size=124, length=-1]
+root@root --(thread)--> 3000@0 [size=124, length=-1]
 1001@0 --(superclass)--> 1000@0 [size=123456780065, length=-1]
 1002@0 --(interface)--> 2001@0 [size=123456780069, length=-1]
 1002@0 --(superclass)--> 1001@0 [size=123456780066, length=-1]