GNU bug report logs - #11884
24.1.50; a regression with pselect(2) on FreeBSD after r108687

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From: help-debbugs <at> gnu.org (GNU bug Tracking System)
To: Paul Eggert <eggert <at> cs.ucla.edu>
Cc: tracker <at> debbugs.gnu.org
Subject: bug#11884: closed (24.1.50; a regression with pselect(2) on
 FreeBSD after r108687)
Date: Tue, 17 Jul 2012 02:28:02 +0000

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Your message dated Mon, 16 Jul 2012 19:20:42 -0700
with message-id <5004CBFA.7040906 <at> cs.ucla.edu>
and subject line Re: 24.1.50; a regression with pselect(2) on FreeBSD after r108687
has caused the debbugs.gnu.org bug report #11884,
regarding 24.1.50; a regression with pselect(2) on FreeBSD after r108687
to be marked as done.

(If you believe you have received this mail in error, please contact
help-debbugs <at> gnu.org.)


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11884: http://debbugs.gnu.org/cgi/bugreport.cgi?bug=11884
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From: Jan Beich <jbeich <at> tormail.org>
To: bug-gnu-emacs <at> gnu.org
Subject: 24.1.50; a regression with pselect(2) on FreeBSD after r108687
Date: Sun, 08 Jul 2012 16:04:08 -1100

Trying to use anything that waits for a process turns emacs into a cpu
hog, e.g. browse-url or vc-annotate. A simple test case is:

  $ emacs -Q
  (start-process "dummy" "*dummy*" "/usr/bin/true")

It does nothing on r108686 but degrades on r108707 (intermediate
revisions do not compile). list-processes still shows `true' despite the
process is long gone:

  Process [v]     Status  Buffer          TTY          Command
  dummy           run     *dummy*         /dev/pts/8   /usr/bin/true

in ktrace(1) it looks like this (repeatedly)

   911 emacs    CALL  ioctl(0x3,FIONREAD,0x7fffffffb47c)
   911 emacs    RET   ioctl 0
   911 emacs    CALL  pselect(0x5,0x7fffffffc850,0x7fffffffc7d0,0,0x7fffffffc7c0,0)
   911 emacs    RET   pselect 1
   911 emacs    CALL  ioctl(0x3,FIONREAD,0x7fffffffb46c)
   911 emacs    RET   ioctl 0
   911 emacs    CALL  read(0x4,0x7fffffffb550,0x1000)
   911 emacs    GIO   fd 4 read 0 bytes
       ""
   911 emacs    RET   read 0

--
FreeBSD 10.0-CURRENT r237800 amd64

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From: Paul Eggert <eggert <at> cs.ucla.edu>
To: Jan Beich <jbeich <at> tormail.org>
Cc: "Herbert J. Skuhra" <hskuhra <at> eumx.net>, 11884-done <at> debbugs.gnu.org
Subject: Re: 24.1.50; a regression with pselect(2) on FreeBSD after r108687
Date: Mon, 16 Jul 2012 19:20:42 -0700

Thanks for that bug report.  Herbert J. Skuhra also
privately reported the same bug, and was gracious enough to
give me a login on a FreeBSD host where I could reproduce
your test case and debug the problem.

I found two related bugs.  First, Emacs's 'configure' script
incorrectly assumed that pthread_sigmask wasn't working on
FreeBSD; this is fixed in Emacs trunk bzr 109107.

Second, the gnulib fallback code for pthread_sigmask
incorrectly assumed that FreeBSD's pthread_sigmask (1729,
NULL, NULL) returns a nonzero error number, which it does
not -- it returns 0.  This is arguably a POSIX-compliance
bug in FreeBSD, but a bug like this is something that should
not make Emacs hang.  This is fixed by Emacs trunk bzr
109099.

I'm marking the bug as done; please feel free to reopen it if
this fix does not work for you.

Here's some URLs if you want to see diffs:

http://bzr.savannah.gnu.org/lh/emacs/trunk/revision/109099

http://bzr.savannah.gnu.org/lh/emacs/trunk/revision/109107

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