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Postings from October 2003
I was a little startled by this too, I thought I had been using
sleep(0) in C to sleep until receiving an ALRM for years, and that
this idiom would fall through to perl. Apparently you
need to set up a handler, even a null handler would work, to
catch the signal instead of the default handler, which
appears to print out "Alarm clock" and crap out. Experiments
and results below:
[david@plaza david]$ perl -le 'sleep 0; print "slept"' &
slept
[1] 1618
[1] Done perl -le 'sleep 0; print "slept"'
[david@plaza david]$ perl -le 'sleep 9990; print "slept"' &
[1] 1622
[david@plaza david]$ kill -ALRM 1622
[david@plaza david]$
[1]+ Alarm clock perl -le 'sleep 9990; print "slept"'
[david@plaza david]$ perl -le '$SIG{ALRM} = sub{ print "alarmed" } ;
sleep 9990;
print "slept"' &
[1] 1623
[david@plaza david]$ kill -ALRM 1623
[david@plaza david]$ alarmed
slept
[david@plaza david]$
On Mon, 2003-10-13 at 03:41, Doug Sibley wrote:
> http://www.perl.com/doc/manual/html/pod/perlfunc/sleep.html
>
> says "May be interrupted if the process receives a signal such as
> SIGALRM" (as do the O'Reilly series of perl books) which led me to
> believe that I could sleep until I sent a SIGALRM at which point the
> process would continue.
>
> You may wish to update either the behavior or comments of the sleep
> function.
>
> - Doug
>
> On Sat, 2003-10-11 at 09:20, Michael G Schwern wrote:
> > Doesn't seem like one to me. The program was killed by a SIGALRM and
> > exited abnormally. Your exit(0) is never reached.
> >
> > perlipc states that Perl "does the default thing" to handle a signal if
> > you don't tell it otherwise. The OS X (ie. BSD) signals(3) man page states
> > that the default action for SIGALRM is to terminate the process.
--
david nicol
"In your own mind, you are the hoopiest frood. That is all that matters."
-- Gargoyle Cabbit
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