Re: Learning to use fork()

[ovedpo15]

Some progress:

my $forks = 0;
foreach my $i (1..3) {
    if ($i == 1 && fork() == 0) {
        $forks++;
        print "Running first with $$ \n";
        
        call_sub1();
        call_sub2();
        call_sub3();
        call_sub4();
        call_sub5();
        call_sub6();
        exit;
    } elsif ($i == 2 && fork() == 0) {
        $forks++;
        print "Running second $$ \n";

        call_sub1();
        call_sub10();
        call_sub3();
        call_sub13();
        call_sub5();
        
        exit;
    } else {
        if (fork() == 0) {
            $forks++;
             print "Running third with $$ \n";
            call_sub1();
            call_sub4();
            call_sub5();
            call_sub15();
            exit;
        }
    }

}

for (1 .. $forks) {
    my $pid = wait();
    print "Parent saw $pid exiting\n";
}

print "done\n";

It really feels messy and not clear. Also, it is not the most efficient because ALL of the 15 calls are not depend one on another. with that logic I can create 15 if-else statements but of course it is not readable and clear. Also, the names are not the same (and all of them gets arguments - I removed them so it will be more easy to see). How should I solve it? Also, should I kill the child process when its done by using exit?

[Aldebaran]

It really feels messy and not clear.

fork is fraught in perl without it really being perl's fault. I had recently endeavored to do some multitasking project that way and became convinced that the implementation is not worth the trade-offs, the first being that it must occur in an eval/die pair. My source looks about like yours, and my results were just about as unsatisfying as well. This is about where I dealt with it first: Re^2: using online translation engines with perl.

Also, should I kill the child process when its done by using exit?

There were a couple posts on that thread that showed how to kill the processes. I used a different way to get done what I needed.

[Anonymous Monk]

It really feels messy and not clear

11_42

You're really asking how to clean 11_42? 11_42 you say? What is 11_42? Exactly!

1 use Proc::Background

#!/usr/bin/perl --
use strict;
use warnings;
use Proc::Background;
my @jobs = (
  [ $^X, 'job1.pl' ],
  [ $^X, 'job2.pl' ],
  [ $^X, 'job3.pl' ],
  [ $^X, 'job4.pl' ],
  [ $^X, 'job5.pl' ],
  [ $^X, 'job6.pl' ],
  [ $^X, 'job7.pl' ],
  [ $^X, 'job8.pl' ],
  [ $^X, 'job9.pl' ],
  [ $^X, 'job10.pl' ],
  [ $^X, 'job11.pl' ],
  [ $^X, 'job12.pl' ],
  [ $^X, 'job13.pl' ],
);

my @procs = map { Proc::Background->new( @$_ ) } @jobs;
while( @procs ){
    @procs = {
      $_->alive
      ? $_
      : ItsOverMaybeRestart($_)
      } map @procs;
    sleep 1;
}
sub ItsOverMaybeRestart {
    my( $proc ) = @_;
...
    return;
}

[AnomalousMonk]

@procs = {
  $_->alive
  ? $_
  : ItsOverMaybeRestart($_)
  } map @procs;

I don't know anything about Proc::Background, but shouldn't that be something like

@procs = map {
  $_->alive
  ? $_
  : ItsOverMaybeRestart($_)
  } @procs;

?