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

[Dmitry Samersoff]

Andreas,

I's not growing - always only two threads.

-Dmitry

On 2014-02-27 14:23, Andreas Eriksson wrote:
> Thanks Dmitry.
> 
> There are no crashes, only an assert that is hit if running with a debug
> build.
> Otherwise the active threads keep growing, like you are seeing.
> 
> It is worrying that they keep growing with the patch as well.
> I will have to look at it and see what can be done.
> 
> Regards,
> Andreas
> 
> On 2014-02-26 21:14, Dmitry Samersoff wrote:
>> Andreas,
>>
>> With JDK7 I didn't observe any crash with or without your patch.
>> Without the patch the number of active threads constantly grows,
>> with patch it remains the same.
>>
>>
>> uname -a
>> FreeBSD samersoff.net 9.2-RELEASE FreeBSD 9.2-RELEASE #1: Thu Jan  2
>> 02:15:13 MSK 2014     dms at minext:/sys/amd64/compile/MIRCAT  amd64
>>
>>
>> With patch:
>>
>> #java -version
>>
>> openjdk version "1.7.0_45"
>> OpenJDK Runtime Environment (build 1.7.0_45-b18)
>> OpenJDK 64-Bit Server VM (build 24.45-b08, mixed mode)
>> Thread 80103f400 has exited with leftover thread-specific data after 4
>> destructor iterations
>>
>> #$JAVA_HOME/bin/java -Djava.library.path=$NATIVE com.test.callback.App
>>
>> Java callback: native thread: 34376799232, java thread: Thread-391, 2
>> active threads
>> Successfully detached native thread 0x801045400
>> Deleting callback
>>
>>
>> Without patch:
>>
>> #/opt/openjdk7/bin/java -version
>>
>> openjdk version "1.7.0_25"
>> OpenJDK Runtime Environment (build 1.7.0_25-b15)
>> OpenJDK 64-Bit Server VM (build 23.21-b01, mixed mode)
>>
>> #/opt/openjdk7/bin/java -Djava.library.path=$NATIVE com.test.callback.App
>>
>> Java callback: native thread: 34376788992, java thread: Thread-402, 404
>> active threads
>> Successfully detached native thread 0x801042c00
>> Deleting callback
>>
>> -Dmitry
>>
>>
>> On 2014-02-10 20:21, 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.