GNU bug report logs - #21424
guile-2.0: SIGALRM signal handler does not get called when guile blocks on I/O

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Package: guile; Reported by: Rob Browning <rlb@HIDDEN>; dated Sun, 6 Sep 2015 17:19:02 UTC; Maintainer for guile is bug-guile@HIDDEN.
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@HIDDEN> to control <at> debbugs.gnu.org. Full text available.

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Subject: Re: bug#21424: Acknowledgement (Bug#685919: guile-1.6: SIGALRM signal
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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@HIDDEN> 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@HIDDEN, 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




Information forwarded to bug-guile@HIDDEN:
bug#21424; Package guile. Full text available.

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Subject: Re: Bug#685919: guile-1.6: SIGALRM signal handler does not get called
 when guile blocks on I/O
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Reference: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=3D765497

Panu Kalliokoski <panu.kalliokoski@HIDDEN> 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@karaihin ~/proj/psyk]$ guile
> guile> (alarm 2)
> 0
> guile> Her=C3=A4tyskello
> [atehwa@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
--=20
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




Acknowledgement sent to Rob Browning <rlb@HIDDEN>:
New bug report received and forwarded. Copy sent to bug-guile@HIDDEN. Full text available.
Report forwarded to bug-guile@HIDDEN:
bug#21424; Package guile. Full text available.
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