This was observed once in jdk 9 119 same binaries run:
Please refer to the test output:

----------messages:(274/12894)----------
command: main B6296310
reason: User specified action: run main/othervm B6296310
Mode: othervm [/othervm specified]
Timeout information:
Running jstack on process 5410
2016-06-02 01:46:38
Full thread dump Java HotSpot(TM) 64-Bit Server VM (9-ea+119 mixed mode):

"Attach Listener" #27 daemon prio=9 os_prio=64 tid=0x0000000000c56800 nid=0x53 waiting on condition [0x0000000000000000]
   java.lang.Thread.State: RUNNABLE

"Thread-1" #26 prio=5 os_prio=64 tid=0x0000000000c35000 nid=0x52 runnable [0xffff80ff991fe000]
   java.lang.Thread.State: RUNNABLE
at sun.nio.ch.DevPollArrayWrapper.poll0(java.base@9-ea/Native Method)
at sun.nio.ch.DevPollArrayWrapper.poll(java.base@9-ea/DevPollArrayWrapper.java:223)
at sun.nio.ch.DevPollSelectorImpl.doSelect(java.base@9-ea/DevPollSelectorImpl.java:97)
at sun.nio.ch.SelectorImpl.lockAndDoSelect(java.base@9-ea/SelectorImpl.java:86)
- locked <0x00000000ffb39798> (a sun.nio.ch.Util$2)
- locked <0x00000000ffb39708> (a java.util.Collections$UnmodifiableSet)
- locked <0x00000000ffb39408> (a sun.nio.ch.DevPollSelectorImpl)
at sun.nio.ch.SelectorImpl.select(java.base@9-ea/SelectorImpl.java:97)
at TestHttpServer$Server.run(TestHttpServer.java:176)

"MainThread" #25 prio=5 os_prio=64 tid=0x0000000000c1d000 nid=0x51 runnable [0xffff80ff993fb000]
   java.lang.Thread.State: RUNNABLE
at java.net.SocketInputStream.socketRead0(java.base@9-ea/Native Method)
at java.net.SocketInputStream.socketRead(java.base@9-ea/SocketInputStream.java:116)
at java.net.SocketInputStream.read(java.base@9-ea/SocketInputStream.java:170)
at java.net.SocketInputStream.read(java.base@9-ea/SocketInputStream.java:141)
at java.io.BufferedInputStream.fill(java.base@9-ea/BufferedInputStream.java:246)
at java.io.BufferedInputStream.read1(java.base@9-ea/BufferedInputStream.java:286)
at java.io.BufferedInputStream.read(java.base@9-ea/BufferedInputStream.java:345)
- locked <0x00000000ffa10860> (a java.io.BufferedInputStream)
at sun.net.www.http.HttpClient.parseHTTPHeader(java.base@9-ea/HttpClient.java:704)
at sun.net.www.http.HttpClient.parseHTTP(java.base@9-ea/HttpClient.java:647)
at sun.net.www.protocol.http.HttpURLConnection.getInputStream0(java.base@9-ea/HttpURLConnection.java:1528)
- locked <0x00000000ffb7c6e0> (a sun.net.www.protocol.http.HttpURLConnection)
at sun.net.www.protocol.http.HttpURLConnection.getInputStream(java.base@9-ea/HttpURLConnection.java:1433)
- locked <0x00000000ffb7c6e0> (a sun.net.www.protocol.http.HttpURLConnection)
at java.net.HttpURLConnection.getResponseCode(java.base@9-ea/HttpURLConnection.java:480)
at B6296310.makeHttpCall(B6296310.java:71)
at B6296310.main(B6296310.java:53)
at jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(java.base@9-ea/Native Method)
at jdk.internal.reflect.NativeMethodAccessorImpl.invoke(java.base@9-ea/NativeMethodAccessorImpl.java:62)
at jdk.internal.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.MainWrapper$MainThread.run(MainWrapper.java:110)
at java.lang.Thread.run(java.base@9-ea/Thread.java:804)

"Service Thread" #23 daemon prio=9 os_prio=64 tid=0x0000000000a7e800 nid=0x4f runnable [0x0000000000000000]
   java.lang.Thread.State: RUNNABLE

"Common-Cleaner" #22 daemon prio=8 os_prio=64 tid=0x000000000092b000 nid=0x4e in Object.wait() [0xffff80ff997de000]
   java.lang.Thread.State: TIMED_WAITING (on object monitor)
at java.lang.Object.wait(java.base@9-ea/Native Method)
- waiting on <0x00000000fff3ea30> (a java.lang.ref.ReferenceQueue$Lock)
at java.lang.ref.ReferenceQueue.remove(java.base@9-ea/ReferenceQueue.java:151)
- waiting to re-lock in wait() <0x00000000fff3ea30> (a java.lang.ref.ReferenceQueue$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:122)

"Sweeper thread" #21 daemon prio=9 os_prio=64 tid=0x00000000008df000 nid=0x4d runnable [0x0000000000000000]
   java.lang.Thread.State: RUNNABLE

"C1 CompilerThread14" #20 daemon prio=9 os_prio=64 tid=0x00000000008d5000 nid=0x4c waiting on condition [0x0000000000000000]
   java.lang.Thread.State: RUNNABLE
   No compile task

"C1 CompilerThread13" #19 daemon prio=9 os_prio=64 tid=0x00000000008d2800 nid=0x4b waiting on condition [0x0000000000000000]
   java.lang.Thread.State: RUNNABLE
   No compile task

"C1 CompilerThread12" #18 daemon prio=9 os_prio=64 tid=0x00000000008c7000 nid=0x4a waiting on condition [0x0000000000000000]
   java.lang.Thread.State: RUNNABLE
   No compile task

"C1 CompilerThread11" #17 daemon prio=9 os_prio=64 tid=0x00000000008b4000 nid=0x49 waiting on condition [0x0000000000000000]
   java.lang.Thread.State: RUNNABLE
   No compile task

"C1 CompilerThread10" #16 daemon prio=9 os_prio=64 tid=0x00000000008a2000 nid=0x48 waiting on condition [0x0000000000000000]
   java.lang.Thread.State: RUNNABLE
   No compile task

"C2 CompilerThread9" #15 daemon prio=9 os_prio=64 tid=0x00000000008a0000 nid=0x47 waiting on condition [0x0000000000000000]
   java.lang.Thread.State: RUNNABLE
   No compile task

"C2 CompilerThread8" #14 daemon prio=9 os_prio=64 tid=0x000000000088e000 nid=0x46 waiting on condition [0x0000000000000000]
   java.lang.Thread.State: RUNNABLE
   No compile task

"C2 CompilerThread7" #13 daemon prio=9 os_prio=64 tid=0x000000000087c800 nid=0x45 waiting on condition [0x0000000000000000]
   java.lang.Thread.State: RUNNABLE
   No compile task

"C2 CompilerThread6" #12 daemon prio=9 os_prio=64 tid=0x0000000000867800 nid=0x44 waiting on condition [0x0000000000000000]
   java.lang.Thread.State: RUNNABLE
   No compile task

"C2 CompilerThread5" #11 daemon prio=9 os_prio=64 tid=0x000000000084d800 nid=0x43 waiting on condition [0x0000000000000000]
   java.lang.Thread.State: RUNNABLE
   No compile task

"C2 CompilerThread4" #10 daemon prio=9 os_prio=64 tid=0x0000000000811800 nid=0x42 waiting on condition [0x0000000000000000]
   java.lang.Thread.State: RUNNABLE
   No compile task

"C2 CompilerThread3" #9 daemon prio=9 os_prio=64 tid=0x0000000000807800 nid=0x41 waiting on condition [0x0000000000000000]
   java.lang.Thread.State: RUNNABLE
   No compile task

"C2 CompilerThread2" #8 daemon prio=9 os_prio=64 tid=0x0000000000803800 nid=0x40 waiting on condition [0x0000000000000000]
   java.lang.Thread.State: RUNNABLE
   No compile task

"C2 CompilerThread1" #7 daemon prio=9 os_prio=64 tid=0x0000000000801800 nid=0x3f waiting on condition [0x0000000000000000]
   java.lang.Thread.State: RUNNABLE
   No compile task

"C2 CompilerThread0" #6 daemon prio=9 os_prio=64 tid=0x00000000007ff800 nid=0x3e waiting on condition [0x0000000000000000]
   java.lang.Thread.State: RUNNABLE
   No compile task

"Signal Dispatcher" #5 daemon prio=9 os_prio=64 tid=0x00000000007fd800 nid=0x3d runnable [0x0000000000000000]
   java.lang.Thread.State: RUNNABLE

"Reference Pending List Locker" #4 daemon prio=9 os_prio=64 tid=0x00000000007fc000 nid=0x3c waiting on condition [0x0000000000000000]
   java.lang.Thread.State: RUNNABLE

"Finalizer" #3 daemon prio=8 os_prio=64 tid=0x00000000007df000 nid=0x3b in Object.wait() [0xffff80ff9b2fd000]
   java.lang.Thread.State: WAITING (on object monitor)
at java.lang.Object.wait(java.base@9-ea/Native Method)
- waiting on <0x00000000fff0d8b0> (a java.lang.ref.ReferenceQueue$Lock)
at java.lang.ref.ReferenceQueue.remove(java.base@9-ea/ReferenceQueue.java:151)
- waiting to re-lock in wait() <0x00000000fff0d8b0> (a java.lang.ref.ReferenceQueue$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=64 tid=0x00000000007d9000 nid=0x3a in Object.wait() [0xffff80ff9b3fe000]
   java.lang.Thread.State: WAITING (on object monitor)
at java.lang.Object.wait(java.base@9-ea/Native Method)
- waiting on <0x00000000fff09618> (a java.lang.ref.Reference$Lock)
at java.lang.Object.wait(java.base@9-ea/Object.java:516)
at java.lang.ref.Reference.tryHandlePending(java.base@9-ea/Reference.java:193)
- waiting to re-lock in wait() <0x00000000fff09618> (a java.lang.ref.Reference$Lock)
at java.lang.ref.Reference$ReferenceHandler.run(java.base@9-ea/Reference.java:155)

"main" #1 prio=5 os_prio=64 tid=0x0000000000431800 nid=0x2 in Object.wait() [0xffff80ffbf18e000]
   java.lang.Thread.State: WAITING (on object monitor)
at java.lang.Object.wait(java.base@9-ea/Native Method)
- waiting on <0x00000000ffc88600> (a java.lang.Thread)
at java.lang.Thread.join(java.base@9-ea/Thread.java:1313)
- waiting to re-lock in wait() <0x00000000ffc88600> (a java.lang.Thread)
at java.lang.Thread.join(java.base@9-ea/Thread.java:1387)
at com.sun.javatest.regtest.agent.MainWrapper.main(MainWrapper.java:74)

"VM Thread" os_prio=64 tid=0x00000000007cc800 nid=0x39 runnable

"GC Thread#0" os_prio=64 tid=0x0000000000446800 nid=0x3 runnable

"GC Thread#1" os_prio=64 tid=0x0000000000447800 nid=0x4 runnable

"GC Thread#2" os_prio=64 tid=0x0000000000449000 nid=0x5 runnable

"GC Thread#3" os_prio=64 tid=0x000000000044a800 nid=0x6 runnable

"GC Thread#4" os_prio=64 tid=0x000000000044c000 nid=0x7 runnable

"GC Thread#5" os_prio=64 tid=0x000000000044d800 nid=0x8 runnable

"GC Thread#6" os_prio=64 tid=0x000000000044f000 nid=0x9 runnable

"GC Thread#7" os_prio=64 tid=0x0000000000450800 nid=0xa runnable

"GC Thread#8" os_prio=64 tid=0x0000000000452000 nid=0xb runnable

"GC Thread#9" os_prio=64 tid=0x0000000000456000 nid=0xc runnable

"GC Thread#10" os_prio=64 tid=0x0000000000457800 nid=0xd runnable

"GC Thread#11" os_prio=64 tid=0x000000000045a800 nid=0xe runnable

"GC Thread#12" os_prio=64 tid=0x000000000045c000 nid=0xf runnable

"GC Thread#13" os_prio=64 tid=0x000000000045d000 nid=0x10 runnable

"GC Thread#14" os_prio=64 tid=0x000000000045e800 nid=0x11 runnable

"GC Thread#15" os_prio=64 tid=0x0000000000460000 nid=0x12 runnable

"GC Thread#16" os_prio=64 tid=0x0000000000461800 nid=0x13 runnable

"GC Thread#17" os_prio=64 tid=0x0000000000463000 nid=0x14 runnable

"GC Thread#18" os_prio=64 tid=0x0000000000464800 nid=0x15 runnable

"GC Thread#19" os_prio=64 tid=0x0000000000466000 nid=0x16 runnable

"GC Thread#20" os_prio=64 tid=0x0000000000467800 nid=0x17 runnable

"GC Thread#21" os_prio=64 tid=0x0000000000469000 nid=0x18 runnable

"GC Thread#22" os_prio=64 tid=0x000000000046a800 nid=0x19 runnable

"G1 Main Marker" os_prio=64 tid=0x00000000004ba000 nid=0x32 runnable

"G1 Marker#0" os_prio=64 tid=0x00000000004bb800 nid=0x33 runnable

"G1 Marker#1" os_prio=64 tid=0x00000000004bf800 nid=0x34 runnable

"G1 Marker#2" os_prio=64 tid=0x00000000004c1000 nid=0x35 runnable

"G1 Marker#3" os_prio=64 tid=0x00000000004c2800 nid=0x36 runnable

"G1 Marker#4" os_prio=64 tid=0x00000000004c4000 nid=0x37 runnable

"G1 Marker#5" os_prio=64 tid=0x00000000004c7800 nid=0x38 runnable

"G1 Refine#0" os_prio=64 tid=0x0000000000490800 nid=0x30 runnable

"G1 Refine#1" os_prio=64 tid=0x000000000048e800 nid=0x2f runnable

"G1 Refine#2" os_prio=64 tid=0x000000000048d000 nid=0x2e runnable

"G1 Refine#3" os_prio=64 tid=0x000000000048b800 nid=0x2d runnable

"G1 Refine#4" os_prio=64 tid=0x000000000048a000 nid=0x2c runnable

"G1 Refine#5" os_prio=64 tid=0x0000000000488000 nid=0x2b runnable

"G1 Refine#6" os_prio=64 tid=0x0000000000486800 nid=0x2a runnable

"G1 Refine#7" os_prio=64 tid=0x0000000000485000 nid=0x29 runnable

"G1 Refine#8" os_prio=64 tid=0x0000000000483800 nid=0x28 runnable

"G1 Refine#9" os_prio=64 tid=0x0000000000482000 nid=0x27 runnable

"G1 Refine#10" os_prio=64 tid=0x0000000000480000 nid=0x26 runnable

"G1 Refine#11" os_prio=64 tid=0x000000000047e800 nid=0x25 runnable

"G1 Refine#12" os_prio=64 tid=0x000000000047d000 nid=0x24 runnable

"G1 Refine#13" os_prio=64 tid=0x000000000047b800 nid=0x23 runnable

"G1 Refine#14" os_prio=64 tid=0x000000000047a000 nid=0x22 runnable

"G1 Refine#15" os_prio=64 tid=0x0000000000478000 nid=0x21 runnable

"G1 Refine#16" os_prio=64 tid=0x0000000000476800 nid=0x20 runnable

"G1 Refine#17" os_prio=64 tid=0x0000000000475000 nid=0x1f runnable

"G1 Refine#18" os_prio=64 tid=0x0000000000473800 nid=0x1e runnable

"G1 Refine#19" os_prio=64 tid=0x0000000000472000 nid=0x1d runnable

"G1 Refine#20" os_prio=64 tid=0x0000000000470000 nid=0x1c runnable

"G1 Refine#21" os_prio=64 tid=0x000000000046e800 nid=0x1b runnable

"G1 Refine#22" os_prio=64 tid=0x000000000046d000 nid=0x1a runnable

"G1 Young RemSet Sampling" os_prio=64 tid=0x0000000000492000 nid=0x31 runnable

"VM Periodic Task Thread" os_prio=64 tid=0x0000000000b19800 nid=0x50 waiting on condition

JNI global references: 263

--- Timeout information end.
elapsed time (seconds): 960.651