RFR: JDK-8033696: "assert(thread != NULL) failed: just checking" due to Thread::current() and JNI pthread interaction

[Dmitry Samersoff]

Andreas,

I'll try with jdk7 tomorrow.

-Dmitry

On 2014-02-24 18:50, Andreas Eriksson wrote:
> Could you try with jdk8 or jdk7?
> The fix should be exactly the same, and if it works one of those it
> should work on all of them.
> 
> /Andreas
> 
> On 2014-02-24 15:48, Dmitry Samersoff wrote:
>> Andreas,
>>
>> (CC'in Greg)
>>
>> I'm not able to compile ojdk9 on FreeBSD (did some cleanup on fly but
>> stuck on NIO)
>>
>> and it's seems like freebsd community don't have patches for JDK 9 yet.
>>
>> -Dmitry
>>
>> On 2014-02-24 16:51, Andreas Eriksson wrote:
>>> Great, thanks.
>>>
>>> /Andreas
>>>
>>> On 2014-02-24 13:15, Dmitry Samersoff wrote:
>>>> Andreas,
>>>>
>>>> I'll check it on FreeBSD 9.x
>>>>
>>>> -Dmitry
>>>>
>>>> On 2014-02-24 15:36, Andreas Eriksson wrote:
>>>>> Thanks Gerard.
>>>>>
>>>>> Do you know if there are any machines with FreeBSD or OpenBSD that
>>>>> I can
>>>>> test this on?
>>>>>
>>>>> Regards,
>>>>> Andreas
>>>>>
>>>>> On 2014-02-20 21:55, Gerard Ziemski wrote:
>>>>>> hi Andreas,
>>>>>>
>>>>>> Mac OS X appears to work similarly and the pthread_key destructor
>>>>>> appears to be only called once.
>>>>>>
>>>>>> So it appears that OS X also does not follow the POSIX spec, but even
>>>>>> if (when) it does in the future, the destructor will be called at
>>>>>> most
>>>>>> PTHREAD_DESTRUCTOR_ITERATIONS times (which on Mac OS X is currently
>>>>>> set to 4), so if we keep our destructor as simple as it is we should
>>>>>> be OK.
>>>>>>
>>>>>> Thank you for the fix.
>>>>>>
>>>>>>
>>>>>> cheers
>>>>>>
>>>>>> On 2/16/2014 6:35 PM, David Holmes wrote:
>>>>>>> Hi Andreas,
>>>>>>>
>>>>>>> As per previous discussions I think this is okay. Normally we don't
>>>>>>> flag changes with the bug ID but in this case I think it is obscure
>>>>>>> enough to warrant that.
>>>>>>>
>>>>>>> I've convinced myself that the order of destructor invocations
>>>>>>> doesn't matter, as long as a simple linear traversal is done that
>>>>>>> checks the values, nulls them and invokes the destructor (if any).
>>>>>>> However if the implementation did this in two passes:
>>>>>>>
>>>>>>> find all non-null values with destructors;
>>>>>>> execute all destructors;
>>>>>>> rinse-repeat
>>>>>>>
>>>>>>> then our destructor would be called multiple times in the normal
>>>>>>> case, as well as the bad case.
>>>>>>>
>>>>>>> So we are relying on the linux and bsd implementation behaviour. We
>>>>>>> already know that neither seem to follow the POSIX spec on this -
>>>>>>> hence the bug. You've verified how linux behaves. But now we need to
>>>>>>> be clear how different BSDs will behave - at least FreeBSD and OSX.
>>>>>>> Hopefully someone from runtime can assist with the analysis on BSD.
>>>>>>>
>>>>>>> Thanks,
>>>>>>> David
>>>>>>>
>>>>>>> On 11/02/2014 2:21 AM, Andreas Eriksson wrote:
>>>>>>>> Hi,
>>>>>>>>
>>>>>>>> Could I please get reviews for this change.
>>>>>>>> JBS: https://bugs.openjdk.java.net/browse/JDK-8033696
>>>>>>>> Webrev: http://cr.openjdk.java.net/~aeriksso/8033696/webrev.00/
>>>>>>>> Mail discussion:
>>>>>>>> http://mail.openjdk.java.net/pipermail/hotspot-runtime-dev/2014-February/010759.html
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>> Summary:
>>>>>>>> JNI code is using pthread_key_create with a destructor to detach
>>>>>>>> the
>>>>>>>> thread from the JVM when the thread is exiting.
>>>>>>>> For some flavors of Linux and BSD the JVM is also using the
>>>>>>>> pthread_key_create, to store the Thread::current() value in a
>>>>>>>> thread
>>>>>>>> local storage.
>>>>>>>> Since the thread local storage containing the thread pointer is
>>>>>>>> erased
>>>>>>>> (by pthread) before the JNI destructor runs, we run
>>>>>>>> detachCurrentThread
>>>>>>>> on a thread that has NULL as current thread.
>>>>>>>> This fix uses a destructor for the thread pointer that restores the
>>>>>>>> value, so that the JNI destructor can run detachCurrentThread
>>>>>>>> successfully.
>>>>>>>> More info in JBS.
>>>>>>>>
>>>>>>>> Testing:
>>>>>>>> Native code regtest attached to JBS tested on Linux, but not on Mac
>>>>>>>> since I don't have access to one.
>>>>>>>> JPRT ran without a problem.
>>>>>>>>
>>>>>>>> Regards,
>>>>>>>> Andreas
>>
> 


-- 
Dmitry Samersoff
Oracle Java development team, Saint Petersburg, Russia
* I would love to change the world, but they won't give me the sources.