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

[Andreas Eriksson]

Thanks Dmitry.

/Andreas

On 2014-04-02 17:36, Dmitry Samersoff wrote:
> Andreas,
>
> Looks good for me!
>
> -Dmitry
>
> On 2014-04-02 19:26, Andreas Eriksson wrote:
>> Thanks David.
>>
>> Could I get a second review as well?
>>
>> Thanks,
>> Andreas
>>
>> On 2014-03-26 10:38, David Holmes wrote:
>>> Still seems okay to me.
>>>
>>> Thanks,
>>> David
>>>
>>> On 25/03/2014 7:55 PM, Andreas Eriksson wrote:
>>>> Hi,
>>>>
>>>> Could I get some eyes on this new webrev?
>>>>
>>>> Thanks,
>>>> Andreas
>>>>
>>>> On 2014-03-04 01:12, Andreas Eriksson wrote:
>>>>> That output was because the VMThread didn't reset it's TLS before
>>>>> exiting (presumably since the VM is shutting down anyway).
>>>>> This meant that the thread pointer destructor was run until the
>>>>> pthread implementation gave up.
>>>>> I added code that sets the thread pointer to NULL before exiting the
>>>>> VMThread, ensuring the thread pointer destructor is never called for
>>>>> the exiting VMThread.
>>>>>
>>>>> A new updated webrev can be found here:
>>>>> http://cr.openjdk.java.net/~aeriksso/8033696/webrev.01/
>>>>>
>>>>> I also removed the bug reference from the comments, since I got the
>>>>> feeling that it's usually discouraged.
>>>>>
>>>>> Thanks,
>>>>> Andreas
>>>>>
>>>>> On 2014-02-27 13:34, Andreas Eriksson wrote:
>>>>>> Oh, sorry, I misread your mail.
>>>>>>
>>>>>> I will look into the pthread output from java -version.
>>>>>>
>>>>>> Thread 80103f400 has exited with leftover thread-specific data after 4
>>>>>> destructor iterations
>>>>>>
>>>>>> Thanks,
>>>>>> Andreas
>>>>>>
>>>>>> On 2014-02-27 12:39, Dmitry Samersoff wrote:
>>>>>>> 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
>