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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