CDV ❯ improper locking in LinkedBlockingQueue.poll()

• Type: Bug
• Status: Open
• Priority: 2 Major
• Resolution:
• Component/s: Byte Code Transform
• Labels:

• Assignee: cdennis
• Reporter: teck
• Created: May 12, 2009
• Votes: 0
• Watchers: 0
• Updated:

  October 11, 2011
• Resolved:

Description

There is no common lock (with respect to put/offer) when an LBQ is empty. It is possible to get an invalid NoSuchElementException from remove() (which is based on poll()) in this case (see DEV-2797). The AtomicInteger inside of LBQ is relevant to behavior of LBQ in this regard but this counter is not clustered – as such you can get back null from poll() since you can race with receiving a broadcast of the put/offer.

The caution here is that naive clustering of that internal counter will probably greater affect (negatively) the effectiev concurrency of an LBQ in the cluster.

Comments

Fiona OShea 2010-10-28

Can we add the workaround to comments?