Re: inconsistent eval timeout

"OPTION 2" doesn't timeout at all, it waits for external command to complete normally. I think because you used backticks instead of system, Perl didn't die in 3 sec but waited until STDOUT of spawned process was closed. This should work:

use strict;
use warnings;

my $timeout_msg = "Timeout after 3 seconds!\n";
my $t = time;
my $pid;
eval {
    local $SIG{ ALRM } = sub { die $timeout_msg };
    alarm 3;
    $pid = system 1, 'timeout /t 6 > nul && echo Good Morning!';
    waitpid $pid, 0;
    alarm 0
};
if ( $@ ) {
    die $@ unless $@ eq $timeout_msg;
    print $@;
    kill 'KILL', $pid
}
print time - $t, "\n";
[download]

I hope my use of timeout command won't confuse you to insert it somewhere in your code:), it's just to emulate long-running process. More important is Perl Windows system extension.

Comment on Re: inconsistent eval timeout Download Code

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Re^2: inconsistent eval timeout by Sanjay (Sexton) on Nov 04, 2019 at 15:45 UTC
Thanks. Works. However, the job keeps running in the background. Is the kill in the code one of the GNU Windows utilities? The & Good Morning! confused me. Why is it there? Presumable a dummy activity, but why? Instead of kill, on Windows I found the following more effective `system("taskkill /F /T /PID $pid");` The /F to force and the /T for all child processes. Please do explain the ... && Good ..., if convenient	[reply] [d/l]
Re^3: inconsistent eval timeout by vr (Curate) on Nov 05, 2019 at 10:37 UTC
Thanks. Works. However, the job keeps running in the background. Is the kill in the code one of the GNU Windows utilities? no, kill is Perl's built-in, used to send any supported signal. Under Win32, it is described to "terminate the process identified by $pid, and make it exit immediately". Apparently, immediate exit is not guaranteed for unresponsive applications, so "taskkill /f" was required in your case. The & Good Morning! confused me. Why is it there? Presumable a dummy activity, but why? Correct, that "echo" part is kind of dummy; single/double (not important in this case) ampersand is to have several commands on one line, and serves no other purpose but to avoid checking for active tasks. Either I observe a "Good Morining!" even after Perl quit (child shell process was not terminated), or not.	[reply]


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