It has been observed 8+ times since M3 integration. It is Mac only

Please refer to the stacks belows

Full thread dump Java HotSpot(TM) 64-Bit Server VM (9-ea+111-mach5-b1867 mixed mode):

"Attach Listener" #955 daemon prio=9 os_prio=31 tid=0x00007ff43b24f000 nid=0x810b waiting on condition [0x0000000000000000]
   java.lang.Thread.State: RUNNABLE

"SameVMThread" #954 prio=5 os_prio=31 tid=0x00007ff43b25d800 nid=0x935f runnable [0x000000012db8b000]
   java.lang.Thread.State: RUNNABLE
at java.io.FileInputStream.readBytes(java.base@9-ea/Native Method)
at java.io.FileInputStream.read(java.base@9-ea/FileInputStream.java:255)
at java.io.BufferedInputStream.read1(java.base@9-ea/BufferedInputStream.java:284)
at java.io.BufferedInputStream.read(java.base@9-ea/BufferedInputStream.java:345)
- locked <0x00000007a3195ea0> (a java.lang.ProcessImpl$ProcessPipeInputStream)
at sun.nio.cs.StreamDecoder.readBytes(java.base@9-ea/StreamDecoder.java:284)
at sun.nio.cs.StreamDecoder.implRead(java.base@9-ea/StreamDecoder.java:326)
at sun.nio.cs.StreamDecoder.read(java.base@9-ea/StreamDecoder.java:178)
- locked <0x00000007a319a118> (a java.io.InputStreamReader)
at java.io.InputStreamReader.read(java.base@9-ea/InputStreamReader.java:185)
at java.io.BufferedReader.fill(java.base@9-ea/BufferedReader.java:161)
at java.io.BufferedReader.readLine(java.base@9-ea/BufferedReader.java:325)
- locked <0x00000007a319a118> (a java.io.InputStreamReader)
at java.io.BufferedReader.readLine(java.base@9-ea/BufferedReader.java:390)
at Utils.runExec(Utils.java:504)
at Utils.runExec(Utils.java:476)
at Utils.createRtJar(Utils.java:585)
at Pack200Props.verifySegmentLimit(Pack200Props.java:59)
at Pack200Props.main(Pack200Props.java:53)
at sun.reflect.NativeMethodAccessorImpl.invoke0(java.base@9-ea/Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(java.base@9-ea/NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(java.base@9-ea/DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(java.base@9-ea/Method.java:531)
at com.sun.javatest.regtest.agent.MainActionHelper$SameVMRunnable.run(MainActionHelper.java:226)
at java.lang.Thread.run(java.base@9-ea/Thread.java:804)

"process reaper" #945 daemon prio=10 os_prio=31 tid=0x00007ff434430000 nid=0x8d5f runnable [0x000000012c5bc000]
   java.lang.Thread.State: RUNNABLE
at java.lang.ProcessHandleImpl.waitForProcessExit0(java.base@9-ea/Native Method)
at java.lang.ProcessHandleImpl.lambda$completion$2(java.base@9-ea/ProcessHandleImpl.java:126)
at java.lang.ProcessHandleImpl$$Lambda$219/1511050819.run(java.base@9-ea/Unknown Source)
at java.util.concurrent.ThreadPoolExecutor.runWorker(java.base@9-ea/ThreadPoolExecutor.java:1158)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(java.base@9-ea/ThreadPoolExecutor.java:632)
at java.lang.Thread.run(java.base@9-ea/Thread.java:804)

"pool-1-thread-1" #13 daemon prio=5 os_prio=31 tid=0x00007ff4350d9800 nid=0x8307 waiting on condition [0x000000012d333000]
   java.lang.Thread.State: TIMED_WAITING (parking)
at jdk.internal.misc.Unsafe.park(java.base@9-ea/Native Method)
- parking to wait for <0x00000007a0105510> (a java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject)
at java.util.concurrent.locks.LockSupport.parkNanos(java.base@9-ea/LockSupport.java:230)
at java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject.awaitNanos(java.base@9-ea/AbstractQueuedSynchronizer.java:2106)
at java.util.concurrent.ScheduledThreadPoolExecutor$DelayedWorkQueue.take(java.base@9-ea/ScheduledThreadPoolExecutor.java:1131)
at java.util.concurrent.ScheduledThreadPoolExecutor$DelayedWorkQueue.take(java.base@9-ea/ScheduledThreadPoolExecutor.java:848)
at java.util.concurrent.ThreadPoolExecutor.getTask(java.base@9-ea/ThreadPoolExecutor.java:1083)
at java.util.concurrent.ThreadPoolExecutor.runWorker(java.base@9-ea/ThreadPoolExecutor.java:1143)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(java.base@9-ea/ThreadPoolExecutor.java:632)
at java.lang.Thread.run(java.base@9-ea/Thread.java:804)

"Service Thread" #12 daemon prio=9 os_prio=31 tid=0x00007ff4350de800 nid=0x7a03 runnable [0x0000000000000000]
   java.lang.Thread.State: RUNNABLE

"Cleaner-0" #11 daemon prio=8 os_prio=31 tid=0x00007ff43425f000 nid=0x7803 in Object.wait() [0x000000012ced7000]
   java.lang.Thread.State: TIMED_WAITING (on object monitor)
at java.lang.Object.wait(java.base@9-ea/Native Method)
- waiting on <no object reference available>
at java.lang.ref.ReferenceQueue.remove(java.base@9-ea/ReferenceQueue.java:151)
- waiting to re-lock in wait() <0x00000007a0104ff0> (a java.lang.ref.ReferenceQueue$Lock)
at jdk.internal.ref.CleanerImpl.run(java.base@9-ea/CleanerImpl.java:148)
at java.lang.Thread.run(java.base@9-ea/Thread.java:804)
at jdk.internal.misc.InnocuousThread.run(java.base@9-ea/InnocuousThread.java:93)

"Sweeper thread" #10 daemon prio=9 os_prio=31 tid=0x00007ff434804800 nid=0x7603 runnable [0x0000000000000000]
   java.lang.Thread.State: RUNNABLE

"C1 CompilerThread3" #9 daemon prio=9 os_prio=31 tid=0x00007ff434803800 nid=0x7403 waiting on condition [0x0000000000000000]
   java.lang.Thread.State: RUNNABLE
   No compile task

"C2 CompilerThread2" #8 daemon prio=9 os_prio=31 tid=0x00007ff434801000 nid=0x7203 waiting on condition [0x0000000000000000]
   java.lang.Thread.State: RUNNABLE
   No compile task

"C2 CompilerThread1" #7 daemon prio=9 os_prio=31 tid=0x00007ff43380a000 nid=0x7003 waiting on condition [0x0000000000000000]
   java.lang.Thread.State: RUNNABLE
   No compile task

"C2 CompilerThread0" #6 daemon prio=9 os_prio=31 tid=0x00007ff433809800 nid=0x6e03 waiting on condition [0x0000000000000000]
   java.lang.Thread.State: RUNNABLE
   No compile task

"Signal Dispatcher" #5 daemon prio=9 os_prio=31 tid=0x00007ff435023800 nid=0x6c03 runnable [0x0000000000000000]
   java.lang.Thread.State: RUNNABLE

"Surrogate Locker Thread (Concurrent GC)" #4 daemon prio=9 os_prio=31 tid=0x00007ff435028000 nid=0x691b waiting on condition [0x0000000000000000]
   java.lang.Thread.State: RUNNABLE

"Finalizer" #3 daemon prio=8 os_prio=31 tid=0x00007ff435021800 nid=0x5403 in Object.wait() [0x000000012c506000]
   java.lang.Thread.State: WAITING (on object monitor)
at java.lang.Object.wait(java.base@9-ea/Native Method)
- waiting on <no object reference available>
at java.lang.ref.ReferenceQueue.remove(java.base@9-ea/ReferenceQueue.java:151)
- waiting to re-lock in wait() <0x00000007a0105bd8> (a java.lang.ref.ReferenceQueue$Lock)
at java.lang.ref.ReferenceQueue.remove(java.base@9-ea/ReferenceQueue.java:172)
at java.lang.ref.Finalizer$FinalizerThread.run(java.base@9-ea/Finalizer.java:216)

"Reference Handler" #2 daemon prio=10 os_prio=31 tid=0x00007ff435020800 nid=0x5203 in Object.wait() [0x000000012c403000]
   java.lang.Thread.State: WAITING (on object monitor)
at java.lang.Object.wait(java.base@9-ea/Native Method)
- waiting on <no object reference available>
at java.lang.Object.wait(java.base@9-ea/Object.java:516)
at java.lang.ref.Reference.tryHandlePending(java.base@9-ea/Reference.java:193)
- waiting to re-lock in wait() <0x00000007a0106be8> (a java.lang.ref.Reference$Lock)
at java.lang.ref.Reference$ReferenceHandler.run(java.base@9-ea/Reference.java:155)

"main" #1 prio=5 os_prio=31 tid=0x00007ff434000000 nid=0x1e03 in Object.wait() [0x000000010df27000]
   java.lang.Thread.State: WAITING (on object monitor)
at java.lang.Object.wait(java.base@9-ea/Native Method)
- waiting on <no object reference available>
at java.lang.Thread.join(java.base@9-ea/Thread.java:1309)
- waiting to re-lock in wait() <0x00000007a3156988> (a java.lang.Thread)
at java.lang.Thread.join(java.base@9-ea/Thread.java:1383)
at com.sun.javatest.regtest.agent.MainActionHelper.runClass(MainActionHelper.java:130)
at com.sun.javatest.regtest.agent.AgentServer.doMain(AgentServer.java:233)
at com.sun.javatest.regtest.agent.AgentServer.run(AgentServer.java:182)
at com.sun.javatest.regtest.agent.AgentServer.main(AgentServer.java:59)

"VM Thread" os_prio=31 tid=0x00007ff435827000 nid=0x5003 runnable

"GC Thread#0" os_prio=31 tid=0x00007ff432807800 nid=0x2603 runnable

"GC Thread#1" os_prio=31 tid=0x00007ff432001000 nid=0x2803 runnable

"GC Thread#2" os_prio=31 tid=0x00007ff432002000 nid=0x2a03 runnable

"GC Thread#3" os_prio=31 tid=0x00007ff432002800 nid=0x2c03 runnable

"GC Thread#4" os_prio=31 tid=0x00007ff434800000 nid=0x2e03 runnable

"GC Thread#5" os_prio=31 tid=0x00007ff434009000 nid=0x3003 runnable

"GC Thread#6" os_prio=31 tid=0x00007ff432808000 nid=0x3203 runnable

"GC Thread#7" os_prio=31 tid=0x00007ff432003000 nid=0x3403 runnable

"G1 Main Marker" os_prio=31 tid=0x00007ff435017800 nid=0x4803 runnable

"G1 Marker#0" os_prio=31 tid=0x00007ff435018800 nid=0x4c03 runnable

"G1 Marker#1" os_prio=31 tid=0x00007ff435019000 nid=0x4e03 runnable

"G1 Refine#0" os_prio=31 tid=0x00007ff435005800 nid=0x4403 runnable

"G1 Refine#1" os_prio=31 tid=0x00007ff435004800 nid=0x4203 runnable

"G1 Refine#2" os_prio=31 tid=0x00007ff435004000 nid=0x4003 runnable

"G1 Refine#3" os_prio=31 tid=0x00007ff435003000 nid=0x3e03 runnable

"G1 Refine#4" os_prio=31 tid=0x00007ff435002800 nid=0x3c03 runnable

"G1 Refine#5" os_prio=31 tid=0x00007ff435001800 nid=0x3a03 runnable

"G1 Refine#6" os_prio=31 tid=0x00007ff435001000 nid=0x3803 runnable

"G1 Refine#7" os_prio=31 tid=0x00007ff435000000 nid=0x3603 runnable

"G1 Young RemSet Sampling" os_prio=31 tid=0x00007ff435006000 nid=0x4603 runnable

"VM Periodic Task Thread" os_prio=31 tid=0x00007ff43589d800 nid=0x7c03 waiting on condition

JNI global references: 2414

--- Timeout information end.
elapsed time (seconds): 480.571