fork a child, then monitor (
alarm+
waitpid) the child in the parent. I'm no expert at working with child processes, but I came up with the following. Once the child has run for $timeout seconds, the parent asks the child to terminate. If the child is still running 10 seconds later, the parent forcefully kills the child.
my @command = "sleep 10; echo awoke";
my $timeout = 5;
my $cpid = fork();
die("Unable to fork: $!\n")
if not defined $cpid;
if (not $cpid) { # In child
exec(@command);
die("Unable to exec: $!\n");
}
eval {
local $SIG{ALRM} = sub { die "alarm\n" };
alarm($timeout);
waitpid($cpid, 0);
};
alarm(0);
if ($@) {
die $@ if $@ ne "alarm\n";
warn("Long running child. Attempting to terminate.\n");
kill 'TERM', $cpid;
eval {
local $SIG{ALRM} = sub { die "alarm\n" };
alarm(10);
waitpid($cpid, 0);
};
alarm(0);
if ($@) {
die $@ if $@ ne "alarm\n";
warn("Long running child. Attempting to kill.\n");
kill 'KILL', $cpid;
eval {
local $SIG{ALRM} = sub { die "alarm\n" };
alarm(5);
waitpid($cpid, 0);
};
alarm(0);
if ($@) {
die $@ if $@ ne "alarm\n";
warn("Unable to kill long running child.\n");
} else {
warn("Long running child successfully killed.\n");
}
} else {
warn("Long running child successfully terminated.\n");
}
}
Output:
$ perl script.pl
Long running child. Attempting to terminate.
Long running child successfully terminated.
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