[RIVER-447] Leaked Executor Service Threads in LoadClass

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: River_3.0.0
• Fix Version/s: River_3.0.1
• Component/s: net_jini_loader
• Labels: PreferredClassLoader leaks threads

Environment

Linux with either JDK 1.7 or 1.8

• Assignee: Peter Firmstone
• Reporter: Shawn Ellis
• Created: 14/Jan/17 15:30
• Updated: 20/Jan/17 10:55
• Resolved: 20/Jan/17 10:55

Description

I am seeing an overall thread usage increase when using Apache River 3.0. I'm able to reproduce the problem with both JDK 1.7 and 1.8. The issue is that LoadClass makes use of a loaderMap that contains an Executor Service. After 10 seconds, the loaderMap will garbage collect the Executor Service, but the Executor Service will not be shutdown. This leaves the Executor Service thread still running and waiting for work.

How to Reproduce:

1. Start up an Apache River 3.0 instance
2. Have a client connect to the River instance
3. Wait 10 seconds
4. Have the client connect to the River instance a second time. The number
of threads will have increased.

The leaked threads have a stack trace similar to the one below.

"net.jini.loader.pref.PreferredClassLoader@7af8260a["httpmd://10.0.1.5:9070/reggie-dl.jar;sha=6c5b83e0caec74d5d4226dcd2c2311d29e81ac0a httpmd://10.0.1.5:9070/jsk-dl.jar;sha=002bca7b77431ba20385d7ca5be8fa8ec1124a01"]_thread-0" #30149 prio=5 os_prio=0 tid=0x00003fff68f79000 nid=0x5db9 waiting on condition [0x00003ffdc344d000]
java.lang.Thread.State: WAITING (parking)
at sun.misc.Unsafe.park(Native Method)

• parking to wait for <0x00000000f2955ff0> (a java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject)
  at java.util.concurrent.locks.LockSupport.park(LockSupport.java:175)
  at java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject.await(AbstractQueuedSynchronizer.java:2039)
  at java.util.concurrent.LinkedBlockingQueue.take(LinkedBlockingQueue.java:442)
  at java.util.concurrent.ThreadPoolExecutor.getTask(ThreadPoolExecutor.java:1067)
  at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1127)
  at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
  at java.lang.Thread.run(Thread.java:745)