Date: Mon, 22 Apr 2013 14:48:28 +0200 From: Sofian Brabez <sbz@FreeBSD.org> To: Gabor Pali <pgj@FreeBSD.org> Cc: python@freebsd.org Subject: Re: Python 2.x Threading on FreeBSD Message-ID: <20130422124828.GA35213@ogoshi.int.nbs-system.com> In-Reply-To: <CAHnG2CxDbP9CVOM-sWvzpYA%2Bm5sH02QywhYo6mdRrQ4WnMHQRg@mail.gmail.com> References: <CAHnG2CxDbP9CVOM-sWvzpYA%2Bm5sH02QywhYo6mdRrQ4WnMHQRg@mail.gmail.com>
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On Sun, Apr 21, 2013 at 07:00:10PM +0200, Gabor Pali wrote:
> Hi there,
>
> Recently I ran into an issue where multi-threaded programs with
> signals cannot be run correctly from a thread in Python 2.x with the
> vanilla lang/python27 port, c.f. [1]. As I wrote in the corresponding
> ticket, the possible cause for this is that threading has been patched
> back in 2009 [2] so I recommended to use GNU pth instead.
>
> However, I managed to catch koobs on IRC yesterday and we continued to
> pursue the reason for this problem further. The aforementioned patch
> was a result of handling ports/131080 [3] where the submitter states
> that this is a solution to a problem where Ctrl+C cannot be handled
> when the main thread is blocked by waiting for another thread. Note
> this patch has been rejected upstream [4]... actually because this is
> not a bug but a feature [5][6].
>
> So could you please fix the lang/python2{6,7} ports by removing the
> following part from the files/patch-Python_thread__pthread.h:
>
> 31 @@ -149,6 +153,7 @@
> 32 {
> 33 pthread_t th;
> 34 int status;
> 35 + sigset_t set, oset;
> 36 #if defined(THREAD_STACK_SIZE) || defined(PTHREAD_SYSTEM_SCHED_SUPPORTED)
> 37 pthread_attr_t attrs;
> 38 #endif
> 39 @@ -177,6 +182,8 @@
> 40 #if defined(PTHREAD_SYSTEM_SCHED_SUPPORTED)
> 41 pthread_attr_setscope(&attrs, PTHREAD_SCOPE_SYSTEM);
> 42 #endif
> 43 + sigfillset(&set);
> 44 + SET_THREAD_SIGMASK(SIG_BLOCK, &set, &oset);
> 45
> 46 status = pthread_create(&th,
> 47 #if defined(THREAD_STACK_SIZE) || defined(PTHREAD_SYSTEM_SCHED_SUPPORTED)
> 48 @@ -188,6 +195,7 @@
> 49 (void *)arg
> 50 );
> 51
> 52 + SET_THREAD_SIGMASK(SIG_SETMASK, &oset, NULL);
> 53 #if defined(THREAD_STACK_SIZE) || defined(PTHREAD_SYSTEM_SCHED_SUPPORTED)
> 54 pthread_attr_destroy(&attrs);
> 55 #endif
>
> Note that I have tested this modification with the program in the
> referenced PR and with the program which is failing and both indeed
> worked as described in the cited sources.
>
>
> PS_1: Thanks koobs for helping me with tracking down this issue!
> PS_2: Please CC in your replies as I am not on this list.
>
> [1] http://hackage.haskell.org/trac/ghc/ticket/7652
> [2] http://svnweb.freebsd.org/ports?view=revision&revision=230031
> [3] http://www.freebsd.org/cgi/query-pr.cgi?pr=131080
> [4] http://bugs.python.org/issue1975
> [5] http://www.regexprn.com/2010/05/killing-multithreaded-python-programs.html
> [6] https://docs.google.com/viewer?a=v&q=cache:fHDVpJgZl7sJ:www.dabeaz.com/python/GIL.pdf+&hl=en&gl=au&pid=bl&srcid=ADGEESg1OQ8O8lXMSVYrJ813iuu6X-G4539buVO20VRwFvGewPv3PJXWVGen_wQi_SpbL4rIOmfQEwiDyPUJnm8NpIBNObBqmeXRUd7W3hH3W2AcdeRCrT3zK1bnmA4ZeqoJJbalUZeS&sig=AHIEtbTvKZ9pjSW3mbITlDqXRDYovlYrew
> (pages 21, 22, 25)
> _______________________________________________
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Hi Gabor,
I had a look in the upstream thread header in the Python source code,
and It appears they remove it too in current [1] and 2.7 branch [2].
I also heavily advice to stay closer to the upstream version, i.e.remove
patches they are unneeded anymore or create undefined behaviour.
+1 to get rid off. In our ports we have to remove the patch
files/patch-Python_thread__pthread.h in port lang/python2{6,7} and ask an
exp-run.
Regards
[1] http://hg.python.org/cpython/file/3bfe8327612a/Python/thread_pthread.h
[2] http://hg.python.org/cpython/file/32a5de0e91d5/Python/thread_pthread.h
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Sofian Brabez
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