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#21424
guile-2.0: SIGALRM signal handler does not get called when guile blocks on I/O
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(Sun, 06 Sep 2015 17:19:02 GMT)
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[If possible, please preserve the -forwarded address in any replies.]
Reference: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=765497
Panu Kalliokoski <panu.kalliokoski <at> gmail.com> writes:
> While playing with guile on my system, I discovered a weird anomaly
> which I could not reproduce on other systems running guile. If I
> install a signal handler for SIGALRM, it won't get called while guile is
> making an I/O system call. To demonstrate:
>
> [atehwa <at> karaihin ~/proj/psyk]$ guile
> guile> (alarm 2)
> 0
> guile> Herätyskello
> [atehwa <at> karaihin ~/proj/psyk]$ guile
> guile> (sigaction SIGALRM (lambda (x) (display "now!") (newline)))
> (0 . 335544320)
> guile> (alarm 2)
> 0
> guile> now a lot more than two seconds has passed, while I wrote this
> now!
> <unnamed port>: In expression now:
> <unnamed port>: Unbound variable: now
> ABORT: (unbound-variable)
> [...]
>
> As you can see, the signal handler gets called as soon as guile returns
> from read(2), already before calling (eval).
>
> I can't get to understand what causes this on my system, because another
> Debian system with exact same versions of guile-1.6, libc6 and
> libguile-ltdl-1 seems to work fine, and interrupts the read(2) call with
> the signal handler.
This appears to still be the case with at least Debian's 2.0.11+1-10
package, and setting the handler to something that doesn't perform IO
has the same effect (i.e. no alarm until you hit return):
(sigaction SIGALRM (lambda (x) (exit 1)))
Thanks
--
Rob Browning
rlb @defaultvalue.org and @debian.org
GPG as of 2011-07-10 E6A9 DA3C C9FD 1FF8 C676 D2C4 C0F0 39E9 ED1B 597A
GPG as of 2002-11-03 14DD 432F AE39 534D B592 F9A0 25C8 D377 8C7E 73A4
Information forwarded
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bug-guile <at> gnu.org
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bug#21424
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(Sun, 06 Sep 2015 17:50:02 GMT)
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Message #8 received at 21424 <at> debbugs.gnu.org (full text, mbox):
retitle 21424 guile-2.0: SIGALRM signal handler does not get called when guile blocks on I/O
thanks
GNU bug Tracking System <help-debbugs <at> gnu.org> writes:
> Thank you for filing a new bug report with debbugs.gnu.org.
Note: I used the wrong bug number (the old guile-1.6 clone) in the
original forwarding.
It should have been 765497, and so the Debian forwarded address would be
765497-forwarded <at> bugs.debian.org, as in the headers above.
Thanks
--
Rob Browning
rlb @defaultvalue.org and @debian.org
GPG as of 2011-07-10 E6A9 DA3C C9FD 1FF8 C676 D2C4 C0F0 39E9 ED1B 597A
GPG as of 2002-11-03 14DD 432F AE39 534D B592 F9A0 25C8 D377 8C7E 73A4
Changed bug title to 'guile-2.0: SIGALRM signal handler does not get called when guile blocks on I/O' from 'Bug#685919: guile-1.6: SIGALRM signal handler does not get called when guile blocks on I/O'
Request was from
Rob Browning <rlb <at> defaultvalue.org>
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control <at> debbugs.gnu.org
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(Sun, 06 Sep 2015 17:50:03 GMT)
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(Fri, 24 Jun 2016 09:18:02 GMT)
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Message #13 received at 21424 <at> debbugs.gnu.org (full text, mbox):
It does seem clear that we have a bug here; evidently signals do not
wake up the reader, neither with readline nor without.
Andy
On Sun 06 Sep 2015 19:18, Rob Browning <rlb <at> defaultvalue.org> writes:
> [If possible, please preserve the -forwarded address in any replies.]
>
> Reference: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=765497
>
> Panu Kalliokoski <panu.kalliokoski <at> gmail.com> writes:
>
>> While playing with guile on my system, I discovered a weird anomaly
>> which I could not reproduce on other systems running guile. If I
>> install a signal handler for SIGALRM, it won't get called while guile is
>> making an I/O system call. To demonstrate:
>>
>> [atehwa <at> karaihin ~/proj/psyk]$ guile
>> guile> (alarm 2)
>> 0
>> guile> Herätyskello
>> [atehwa <at> karaihin ~/proj/psyk]$ guile
>> guile> (sigaction SIGALRM (lambda (x) (display "now!") (newline)))
>> (0 . 335544320)
>> guile> (alarm 2)
>> 0
>> guile> now a lot more than two seconds has passed, while I wrote this
>> now!
>> <unnamed port>: In expression now:
>> <unnamed port>: Unbound variable: now
>> ABORT: (unbound-variable)
>> [...]
>>
>> As you can see, the signal handler gets called as soon as guile returns
>> from read(2), already before calling (eval).
>>
>> I can't get to understand what causes this on my system, because another
>> Debian system with exact same versions of guile-1.6, libc6 and
>> libguile-ltdl-1 seems to work fine, and interrupts the read(2) call with
>> the signal handler.
>
> This appears to still be the case with at least Debian's 2.0.11+1-10
> package, and setting the handler to something that doesn't perform IO
> has the same effect (i.e. no alarm until you hit return):
>
> (sigaction SIGALRM (lambda (x) (exit 1)))
>
> Thanks
This bug report was last modified 7 years and 330 days ago.
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