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Subject: |
24.1.50; a regression with pselect(2) on FreeBSD after r108687 |
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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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--- Begin Message ---
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Subject: |
Re: 24.1.50; a regression with pselect(2) on FreeBSD after r108687 |
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Date: |
Mon, 16 Jul 2012 19:20:42 -0700 |
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User-agent: |
Mozilla/5.0 (X11; Linux i686; rv:13.0) Gecko/20120615 Thunderbird/13.0.1 |
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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