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

[Greg Lewis]

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.

-- 
Greg Lewis                          Email   : glewis at eyesbeyond.com
Eyes Beyond                         Web     : http://www.eyesbeyond.com
Information Technology              FreeBSD : glewis at FreeBSD.org