NAME
Time::Limit - kill your broken Perl script
SYNOPSIS
use strict;
use warnings;
use Time::Limit '0.5';
while (1) {
print "infinite loop\n";
}
DESCRIPTION
It is oh so very easy to accidentally write a Perl script that dives
straight into an infinite loop, or stumbles into a runaway recursion. In
most cases, you can hit `Ctrl + C` and get on with the job of figuring out
what went wrong. However, if you're not running the process in a local
terminal (e.g. you're running it over a slow SSH connection, or not in a
terminal at all), these processes might be tricky to kill.
The Time::Limit module starts a monitor process that shadows your script's
execution, and kills it off if your script has overrun its allotted time
limit. Because Time::Limit is global in effect its use in modules is
discouraged. Instead, use it only in your main script, or pass it as a
parameter to Perl on the command line:
perl -MTime::Limit myscript.pl
The syntax for using Time::Limit is:
use Time::Limit @flags, $limit;
Flags are strings prefixed with a hyphen. The following flags are
supported:
`-group`
Send the signal to your script's process group instead of its
individual process number. That is, your script and any child
processes started with `fork` will be killed.
`-quiet`
Kill the script quietly.
`-verbose`
Output extra debugging information.
The $limit is a number indicating the time in seconds before your script
gets killed. It does not have to be an integer. It defaults to a very
generous 10.
Be careful to avoid triggering Perl's `use MODULE VERSION` syntax.
use Time::Limit -verbose, 4.0; # yep, kill after 4 seconds
use Time::Limit '4.0'; # yep, kill after 4 seconds
use Time::Limit 4.0; # nah, want $VERSION==4.0
After $limit is reached, Time::Limit will try signalling your script to
terminate cleanly (SIGTERM) a few times; if that fails, it will become
more aggressive and send SIGKILL signals until it receives word of your
script's timely death.
Some random examples using Time::Limit from the command-line:
perl -MTime::Limit=-quiet,4 myscript.pl
perl -MTime::Limit=-group,-verbose,4.1 myscript.pl
perl -MTime::Limit=3 myscript.pl
BUGS
Please report any bugs to
<
http://rt.cpan.org/Dist/Display.html?Queue=Time-Limit>.
SEE ALSO
Time::Out - this allows you to apply a timeout to an individual block of
code, and then gracefully carry on.
AUTHOR
Toby Inkster <
[email protected]>.
COPYRIGHT AND LICENCE
This software is copyright (c) 2013 by Toby Inkster.
This is free software; you can redistribute it and/or modify it under the
same terms as the Perl 5 programming language system itself.
DISCLAIMER OF WARRANTIES
THIS PACKAGE IS PROVIDED "AS IS" AND WITHOUT ANY EXPRESS OR IMPLIED
WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
