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

[Dmitry Samersoff]

Greg,

Could you send me a patch for compilable jdk8 port?

It's much easy to me to try JDK8 than JDK7.

-Dmitry

On 2014-02-25 10:06, Greg Lewis wrote:
> I have a compilable (I think -- it's been a little while) jdk8 port if you
> would like me to test on there too.  Testing on jdk7 should be sufficient
> though.
> 
> -- Greg
> 
> On Mon, Feb 24, 2014 at 06:59:00PM +0400, Dmitry Samersoff wrote:
>> 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.
> 


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