I need your esteemed help on some wierd behaviour of alarms in ActivePerl. I am using v5.12.2 on Windows 2008 SP1 32bit.

I want to read from a long-running co-process until I am tired, then kill the co-process. I boiled down my code to the following snippet, replacing the real co-process with a dummy command:

#! /usr/bin/perl -w

use strict;

# Starting a co-process to read from.
my $procid = open(READ, '-|', 'perl -e "$|=1; for ($i=0;$i<10;$i++) {p
+rint \"Line $i\n\"; sleep 1;}"');

my $timeout = 0;
$SIG{ALRM} = sub { $timeout = 1; };
alarm(3);

# Reading from co-process.
while (!$timeout) {
    my $line = <READ>;
    last unless defined $line;
    print $line;
#   for (my $i=0;$i<5000;$i++) {}
}

kill('INT', $procid) if $timeout;
[download]

I could not make the alarm work. I even tried unsafe signals. However, putting some tedious calculations somewhere inside the loop, will strangely solve the problem. Must this be considered as a bug?

I also experimented with threads and semaphores and finally found a work-around. But that would be an awful bunch of code for something quite obvious. Is there a state-of-the-art solution to this?

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Thank you, Monks, for all your helpful answers. I will have to study and try for a while to understand all the implications of your proposals. The next thing, I will probably do, is using Win32::Job and/or Win32::Process. These sound quite reasonable and easy to interface, although, alas, they will impair portability of my code.