[SLING-7432] Thread pool clean up code can lead to infinite loops in ThreadLocal.get

• Type: Bug
• Status: Resolved
• Priority: Blocker
• Resolution: Fixed
• Affects Version/s: Commons Threads 3.2.10
• Fix Version/s: Commons Threads 3.2.16
• Component/s: Commons
• Assignee: Robert Munteanu
• Reporter: Robert Munteanu
• Created: 23/Jan/18 13:54
• Updated: 01/Feb/18 09:55
• Resolved: 25/Jan/18 13:36

Description

The thread local clean up code added in SLING-6261 leads to Threads stuck in ThreadLocal.get.

I am working on a simplified test case, but the stack trace is similar to

"pool-1-thread-1" prio=10 tid=0x00007f47f4374800 nid=0xb19 runnable [0x00007f47e734e000]
   java.lang.Thread.State: RUNNABLE
	at java.lang.ThreadLocal$ThreadLocalMap.set(ThreadLocal.java:429)
	at java.lang.ThreadLocal$ThreadLocalMap.access$100(ThreadLocal.java:261)
	at java.lang.ThreadLocal.set(ThreadLocal.java:183)
	at org.apache.sling.commons.threads.impl.ThreadPoolExecutorCleaningThreadLocalsTest$RunnableImplementation.run(ThreadPoolExecutorCleaningThreadLocalsTest.java:100)
	at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:471)
	at java.util.concurrent.FutureTask.run(FutureTask.java:262)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
	at java.lang.Thread.run(Thread.java:745)

Issue Links

• is broken by: SLING-6261 ThreadExpiringThreadPool is relying on uncaught exceptions to kill threads
• is duplicated by: SLING-7300 CPU spike in i18n job