[HDFS-6057] DomainSocketWatcher.watcherThread should be marked as daemon thread

• Type: Bug
• Status: Closed
• Priority: Blocker
• Resolution: Fixed
• Affects Version/s: 2.4.0
• Fix Version/s: 2.4.0
• Component/s: hdfs-client
• Target Version/s: 2.4.0
• Assignee: Colin McCabe
• Reporter: Eric Sirianni
• Created: 05/Mar/14 14:13
• Updated: 10/Apr/14 13:11
• Resolved: 06/Mar/14 08:04

Description

Running the tip of branch-2.4, I'm observing some zombie processes in my environment. jstack shows the following thread preventing the JVM from shutting down:

"Thread-3" prio=10 tid=0x00007f0a908a5800 nid=0x3ee9 runnable [0x00007f0a89471000]
   java.lang.Thread.State: RUNNABLE
	at org.apache.hadoop.net.unix.DomainSocketWatcher.doPoll0(Native Method)
	at org.apache.hadoop.net.unix.DomainSocketWatcher.access$800(DomainSocketWatcher.java:52)
	at org.apache.hadoop.net.unix.DomainSocketWatcher$1.run(DomainSocketWatcher.java:455)
	at java.lang.Thread.run(Thread.java:679)

Marking the DomainSocketWatcher.watcherThread as a daemon thread would prevent this situation. Is there any reason it isn't classified as such?

Also, tracing through the code, I don't see any code path where DomainSocketWatcher.close() is invoked (though this would seem to be a larger issue – maybe I'm missing something...).