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From "Trustin Lee" <trus...@gmail.com>
Subject Re: Warning: serious VM leak/bug with BlockingQueue & polling timeouts
Date Wed, 22 Nov 2006 01:11:50 GMT
On 11/22/06, Holger Hoffstaette <holger@wizards.de> wrote:
>
>
> Here's a heads up for those of you who have the source handy to check.
>
> Both JDK 1.5 and 1.6 have serious confirmed bugs that leak unreclaimable
> memory and will bring *idle* servers down, e.g. during the night or over
> the weekend when load is low or nonexistent. For more information see
> http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=6460501 and related.
>
> In a nutshell BlockingQueue.poll(duration, TimeUnit) will leak *when that
> wait times out*; it will not leak when something is returned from the
> queue, as is the case with uninterrupted non-timed polling.
>
> The bug is confirmed and serious because it triggers extremely nasty GC
> panic that has the potential to bring the whole machine down due to
> excessive CPU spinning and unresponsiveness of the VM to external signals.
>
> I think it would be good if someone with the source would do a quick "find
> all references to method" to see if and how Mina is affected by this. I
> would not be surprised if this is the reason behind some reported leaks -
> polling with timeout is extremely useful for service scheduling in various
> forms and generally preferrable to complete blocking.


Wow, this is shocking.  Even Doug Lea and his co-workers make a mistake! :)
I think the reason why this bug is found so late is because most people
doesn't specify the polling timeout like we didn't for MINA.

Trustin
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