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Re: system() with timeout
by Abigail-II (Bishop) on Mar 18, 2004 at 15:52 UTC
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Don't do it with system directly, or you might generate zombies. fork(), do an exec() in the child, and then, in
an eval block, setup an alarm handler that does a die(),
set the alarm, waitpid() for your child, cancel the alarm.
Outside the eval block, check for $@, if it indicates the
alarm was triggered, kill the child and waitpid() for it.
No doubt there are some race conditions left in, but it's a
start.
Abigail | [reply] |
Re: system() with timeout
by delirium (Chaplain) on Mar 18, 2004 at 15:53 UTC
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Yes. Here's an example of some code I use that does this (but alarm, as I've heard, may be unsafe in older Perls):
#!/usr/bin/perl
use strict;
use warnings;
my $timeout = 180;
my @array = (
"command 1 goes here",
"command 2 goes here",
"command 3 goes here",
);
for (@array) {
eval {
local $SIG{ALRM} = sub {
die "alarm\n";
};
alarm $timeout;
system($_);
alarm 0;
};
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[d/l] |
Re: system() with timeout
by valdez (Monsignor) on Mar 18, 2004 at 15:59 UTC
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... and if you are lazy, take a look at IPC::Run :)
update: many thanks to waswas-fng (who was not lazy)
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One thing I have been bitten on before using IPC::Run is pty issues on heavy loaded machines -- it caused a hard to track down error for me. from the pod:
=item pty Support
If you need pty support, IPC::Run should work well enough most of the
time, but IO::Pty is being improved, and IPC::Run will be improved to
use IO::Pty's new features when it is release.
The basic problem is that the pty needs to initialize itself before the
parent writes to the master pty, or the data written gets lost. So
IPC::Run does a sleep(1) in the parent after forking to (hopefully) give
the child a chance to run. This is a kludge that works well on non
heavily loaded systems :(.
Update: I am not saying its a bad module, just that I have hit the pty issue before and it was a PITA to track down. My fix was to change the sleep 1 to sleep 2 in the module, but there is still a race condition there you just make it a little less likely to happen.
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Re: system() with timeout
by Tomte (Priest) on Mar 18, 2004 at 15:51 UTC
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Super Search for 'system timeout', and you will find what you seek; if I err on that, refer to have a closer look on perldoc -f alarm
regards,
tomte
Hlade's Law:
If you have a difficult task, give it to a lazy person --
they will find an easier way to do it.
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Re: system() with timeout
by ambrus (Abbot) on Mar 18, 2004 at 15:59 UTC
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Dang. I'm stuck with 5.6.1, so it looks like the alarm method isn't going to work for me...
---
A fair fight is a sign of poor planning.
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Re: system() with timeout
by eyepopslikeamosquito (Archbishop) on Mar 19, 2004 at 06:19 UTC
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If you are using Win2K and above, I recommend the Win32::Job module.
Some example code, using either Win32::Process or Win32::Job, can be found in
Timing Windows commands.
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