[HDFS-1529] Incorrect handling of interrupts in waitForAckedSeqno can cause deadlock

• Type: Bug
• Status: Closed
• Priority: Blocker
• Resolution: Fixed
• Affects Version/s: 0.22.0
• Fix Version/s: 0.22.0
• Component/s: hdfs-client
• Hadoop Flags: Reviewed
• Assignee: Todd Lipcon
• Reporter: Todd Lipcon
• Created: 06/Dec/10 18:49
• Updated: 12/Dec/11 06:18
• Resolved: 04/Feb/11 21:13

Description

In HDFS-895 the handling of interrupts during hflush/close was changed to preserve interrupt status. This ends up creating an infinite loop in waitForAckedSeqno if the waiting thread gets interrupted, since Object.wait() has a strange semantic that it doesn't give up the lock even momentarily if the thread is already in interrupted state at the beginning of the call.

We should decide what the correct behavior is here - if a thread is interrupted while it's calling hflush() or close() should we (a) throw an exception, perhaps InterruptedIOException (b) ignore, or (c) wait for the flush to finish but preserve interrupt status on exit?