This has been observed once during same binaries run with b23 which is the first build with consolidated repository.

Please refer to the snippet of test output. The whole log has been attached too.

command: main FtpURLConnectionLeak
reason: User specified action: run main FtpURLConnectionLeak
Mode: agentvm
Agent id: 12
Timeout signalled after 960 seconds
Timeout information:
Running jstack on process 27272
2017-09-12 05:46:44
Full thread dump Java HotSpot(TM) 64-Bit Server VM (10-ea+23 mixed mode):

"Attach Listener" #486 daemon prio=9 os_prio=0 tid=0x00007fe454001000 nid=0x2574 waiting on condition [0x0000000000000000]
   java.lang.Thread.State: RUNNABLE

"SameVMThread" #482 prio=5 os_prio=0 tid=0x00007fe55c374000 nid=0x3349 runnable [0x00007fe1298d6000]
   java.lang.Thread.State: RUNNABLE
at java.net.SocketInputStream.socketRead0(java.base@10-ea/Native Method)
at java.net.SocketInputStream.socketRead(java.base@10-ea/SocketInputStream.java:116)
at java.net.SocketInputStream.read(java.base@10-ea/SocketInputStream.java:171)
at java.net.SocketInputStream.read(java.base@10-ea/SocketInputStream.java:141)
at java.io.BufferedInputStream.fill(java.base@10-ea/BufferedInputStream.java:252)
at java.io.BufferedInputStream.read(java.base@10-ea/BufferedInputStream.java:271)
- locked <0x00000000ef6363a8> (a java.io.BufferedInputStream)
at sun.net.ftp.impl.FtpClient.readServerResponse(java.base@10-ea/FtpClient.java:419)
at sun.net.ftp.impl.FtpClient.readReply(java.base@10-ea/FtpClient.java:496)
at sun.net.ftp.impl.FtpClient.connect(java.base@10-ea/FtpClient.java:1019)
at sun.net.ftp.impl.FtpClient.connect(java.base@10-ea/FtpClient.java:1004)
at sun.net.www.protocol.ftp.FtpURLConnection.connect(java.base@10-ea/FtpURLConnection.java:293)
- locked <0x00000000ef62cc30> (a sun.net.www.protocol.ftp.FtpURLConnection)
at sun.net.www.protocol.ftp.FtpURLConnection.getInputStream(java.base@10-ea/FtpURLConnection.java:401)
at java.net.URL.openStream(java.base@10-ea/URL.java:1117)
at FtpURLConnectionLeak.main(FtpURLConnectionLeak.java:49)
at jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(java.base@10-ea/Native Method)
at jdk.internal.reflect.NativeMethodAccessorImpl.invoke(java.base@10-ea/NativeMethodAccessorImpl.java:62)
at jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(java.base@10-ea/DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(java.base@10-ea/Method.java:564)
at com.sun.javatest.regtest.agent.MainActionHelper$SameVMRunnable.run(MainActionHelper.java:230)
at java.lang.Thread.run(java.base@10-ea/Thread.java:844)

"InnocuousThread-33" #156 daemon prio=5 os_prio=0 tid=0x00007fe3e8481800 nid=0x2b40 waiting on condition [0x00007fe44824f000]
   java.lang.Thread.State: WAITING (parking)
at jdk.internal.misc.Unsafe.park(java.base@10-ea/Native Method)
- parking to wait for <0x00000000e8778990> (a java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject)
at java.util.concurrent.locks.LockSupport.park(java.base@10-ea/LockSupport.java:194)
at java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject.await(java.base@10-ea/AbstractQueuedSynchronizer.java:2062)
at java.util.concurrent.ArrayBlockingQueue.take(java.base@10-ea/ArrayBlockingQueue.java:417)
at sun.nio.ch.EPollPort$EventHandlerTask.run(java.base@10-ea/EPollPort.java:262)
at sun.nio.ch.AsynchronousChannelGroupImpl$1.run(java.base@10-ea/AsynchronousChannelGroupImpl.java:112)
at java.util.concurrent.ThreadPoolExecutor.runWorker(java.base@10-ea/ThreadPoolExecutor.java:1145)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(java.base@10-ea/ThreadPoolExecutor.java:630)
at java.lang.Thread.run(java.base@10-ea/Thread.java:844)
at jdk.internal.misc.InnocuousThread.run(java.base@10-ea/InnocuousThread.java:122)

"InnocuousThread-32" #155 daemon prio=5 os_prio=0 tid=0x00007fe3e847f800 nid=0x2b3f waiting on condition [0x00007fe448350000]
   java.lang.Thread.State: WAITING (parking)
at jdk.internal.misc.Unsafe.park(java.base@10-ea/Native Method)
- parking to wait for <0x00000000e8778990> (a java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject)
at java.util.concurrent.locks.LockSupport.park(java.base@10-ea/LockSupport.java:194)
at java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject.await(java.base@10-ea/AbstractQueuedSynchronizer.java:2062)
at java.util.concurrent.ArrayBlockingQueue.take(java.base@10-ea/ArrayBlockingQueue.java:417)
at sun.nio.ch.EPollPort$EventHandlerTask.run(java.base@10-ea/EPollPort.java:262)
at sun.nio.ch.AsynchronousChannelGroupImpl$1.run(java.base@10-ea/AsynchronousChannelGroupImpl.java:112)
at java.util.concurrent.ThreadPoolExecutor.runWorker(java.base@10-ea/ThreadPoolExecutor.java:1145)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(java.base@10-ea/ThreadPoolExecutor.java:630)
at java.lang.Thread.run(java.base@10-ea/Thread.java:844)
at jdk.internal.misc.InnocuousThread.run(java.base@10-ea/InnocuousThread.java:122)