You have to learn about fork-ing and managing child processes. Here's some example code:
use POSIX qw(:sys_wait_h);
sub doit {
my $pid = fork();
unless (defined($pid)) { die "unable to fork: $!\n"; }
if ($pid) { # parent
# wait for child to finish and display waiting message
my $start = time;
while (1) {
print "time spent waiting: ", time - $start, "\n";
last if (waitpid($pid, WNOHANG) > 0);
sleep(2);
}
# child process has terminated
# read results from file
open(R, "<results-from-child-process");
while (<R>) { ... process results... };
close(R);
} else { # child
# perform time consuming computation here.
...
# leave results in some file
open(R, ">results-from-child-process");
print R ...;
close(R);
exit(0);
}
}
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