How to timeout if a call to an external program takes too long

deivakumar has asked for the wisdom of the Perl Monks concerning the following question:

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Re: How to timeout if a call to an external program takes too long by BrowserUk (Patriarch) on Aug 30, 2007 at 01:54 UTC
You posted in the wrong place, but hopefully that will be corrected. Meantime, one solution is Re: Backticks and SIGALRM. There are other possible solutions in that same thread. Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error. "Science is about questioning the status quo. Questioning authority". In the absence of evidence, opinion is indistinguishable from prejudice. "Too many [] have been sedated by an oppressive environment of political correctness and risk aversion."	[reply]
Re^2: How to timeout if a call to an external program takes too long by deivakumar (Initiate) on Aug 30, 2007 at 05:28 UTC
That is just a perfect solution for me. Thanks a bunch to all who responded.	[reply]
Re: How to timeout if a call to an external program takes too long by kyle (Abbot) on Aug 30, 2007 at 02:07 UTC
Can we see the non-working code that uses alarm? This is a textbook example of when to use `alarm`. Here, the alarm is triggered, and then processing continues: alarm 5; $SIG{ALRM} = sub { print "alarm!\n" }; my $yawn = `sleep 10 ; echo "yawn"`; print "yawn? $yawn\n"; __END__ alarm! yawn? yawn [download] In this case (adapted from the example in the alarm documentation), the alarm is triggered, and processing is halted: my $yawn; eval { local $SIG{ALRM} = sub { die "alarm\n" }; alarm 5; $yawn = `sleep 10 ; echo "yawn"`; alarm 0; }; print $@ ? 'Timed out.' : 'Finished.'; print "\n"; print "yawn? $yawn\n"; __END__ Timed out. yawn? [download]	[reply] [d/l] [select]
Re^2: How to timeout if a call to an external program takes too long by BrowserUk (Patriarch) on Aug 30, 2007 at 03:16 UTC
Have you tried that when safe signals are in force? It certainly doesn't work on the OPs platform (win32 going by his use of MyProgram.exe). I believe that it also doesn't work on *nix platforms since 5.8.0 unless you explicitly disable safe signals . Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error. "Science is about questioning the status quo. Questioning authority". In the absence of evidence, opinion is indistinguishable from prejudice. "Too many [] have been sedated by an oppressive environment of political correctness and risk aversion."	[reply]
Re^3: How to timeout if a call to an external program takes too long by kyle (Abbot) on Aug 30, 2007 at 03:37 UTC
I tried both of my code snippets before posting. My platform is Perl 5.8 on OS X: `kyle@sulaco:~ $ perl -v \| head -6 This is perl, v5.8.6 built for darwin-thread-multi-2level (with 3 registered patches, see perl -V for more detail) Copyright 1987-2004, Larry Wall kyle@sulaco:~ $ uname -a Darwin sulaco 8.10.0 Darwin Kernel Version 8.10.0: Wed May 23 16:50:59 + PDT 2007; root:xnu-792.21.3~1/RELEASE_PPC Power Macintosh powerpc` [download] I did nothing to disable safe signals. The only part of what I actually executed that I left out of what I posted was my usual "`use strict;use warnings;`" (and I also cut out the "Use of uninitialized value..." warning that resulted). I don't have a Windows machine to test on.	[reply] [d/l] [select]
Re^4: How to timeout if a call to an external program takes too long by BrowserUk (Patriarch) on Aug 30, 2007 at 04:10 UTC
Re^5: How to timeout if a call to an external program takes too long by kyle (Abbot) on Aug 30, 2007 at 04:32 UTC
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