[concurrency-interest] ReentrantLock bug?

Vitaly Davidovich vitalyd at gmail.com
Thu Mar 19 18:03:24 EDT 2015


Hmm, the symptoms seem very similar to the set of bugs (should've been
fixed by 7u21 time though, AFAIR) that were filed due to missing barriers
in the native Parker class.  In those cases, -XX:+UseMembar masked the
problem and things worked -- has that been tried with the copy of RL?

Also, what exactly are the differences between the JDK RL and the "nearly
unmodified" one?

On Thu, Mar 19, 2015 at 5:34 PM, Dr Heinz M. Kabutz <
heinz at javaspecialists.eu> wrote:

> The initial discovery was shown here: https://github.com/rafaelbrandao/msc
>
> Regards
>
> Heinz
> --
> Dr Heinz M. Kabutz (PhD CompSci)
> Author of "The Java(tm) Specialists' Newsletter"
> Sun/Oracle Java Champion since 2005
> JavaOne Rock Star Speaker 2012
> http://www.javaspecialists.eu
> Tel: +30 69 75 595 262
> Skype: kabutz
>
>
>
> Dr Heinz M. Kabutz wrote:
>
>> Hi Dmitry,
>>
>> is it possible to send me a sanitized stack trace of what state the
>> thread would be in if RL caused a hang?  Someone reported a very strange
>> behaviour a long time ago on Linux with JDK 7, where you could sometimes
>> get a thread that was waiting for a lock, even though it was Unlocked.  The
>> lock they used was a direct copy of ReentrantLock, with the only difference
>> being that it had been not been loaded in the system class loader.  I
>> managed to reproduce it, although not sure of the exact version of Java 7.
>> After several day of chasing it, I ran out of time and left it, but I've
>> always had the niggling suspicion that it might be a bug that lives fine
>> and well in the ReentrantLock.
>>
>> This was for Java 1.7.0_40, -server.  I thus do not share Aleksey's
>> optimism that moving over to that version is going to make the problem go
>> away.  I could not reproduce it on 1.8, but that might have just been a
>> coincidence.  It was quite difficult to reproduce.
>>
>> BTW, not a silly report / question at all.  Very important indeed,
>> especially considering how many classes in JDK use ReentrantLock internally
>> :-(((
>>
>> Regards
>>
>> Heinz
>>
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