Re: forking and ipc

i'm not a real wizard, but i managed to scrape this together. it seems to do the generic task of running pieces of data (isos) through resources (burners) and waiting for a resource to finish before continuing.

hope this helps.

#!perl -l

use strict;
use warnings;

# make WNOHANG available
use POSIX ":sys_wait_h";

our %jobs;                      # track pid -> resource
our @resource = qw{a b c};      # concurrent resources
my @data = qw{5 4 3 2 1 0};     # data to run through a resource

$SIG{"CHLD"} = sub {
        my $chld;
        $chld = waitpid(-1, WNOHANG) until $chld;
        return unless $chld > 0;
        print "$$ sees $chld is done";
        print "resource " . $jobs{$chld} . " is free again!";
        push @resource, $jobs{$chld};
        delete $jobs{$chld};
        alarm 0;        # send SIGALRM so sleep() wakes up
};

sub runcmd {
        my ($resource, $data) = @_;
        my @cmd = ("sleep", $data);     # define command
        print ">>> $$ runcmd($resource, $data) start";
        system @cmd;                    # run command
        print "<<< $$ runcmd($resource, $data) end";
}

print "main pid: $$";

while (@data) {
        my ($data, $resource, $chld) = shift @data;
        print "sleep ... resource(@resource), data(@data)";
        sleep until @resource;
        print "done sleeping! resource(@resource), data(@data)";
        $resource = shift @resource;
        if (($chld = fork()) > 0) {
                # parent code
                $jobs{$chld} = $resource;
        } else {
                # child code
                runcmd($resource, $data);
                exit;           # end chld, trigger $SIG{CHLD}
        }

}

sleep until keys %jobs == 0;    # wait for all jobs

print "all done!";
[download]

perl -e'$_="nwdd\x7F^n\x7Flm{{llql0}qs\x14";s/./chr(ord$&^30)/ge;print'

Comment on Re: forking and ipc Download Code

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Re: Re: forking and ipc by pizza_milkshake (Monk) on May 03, 2004 at 05:15 UTC
i just realized upon reviewing your description that you want to run a round of burns, then reload all drives at the same time, then do another round, etc. to achieve this, replace the main loop with this: `my $chld; while (@data) { while (@resource) { last unless @data; my $resource = shift @resource; my $data = shift @data; if (($chld = fork()) > 0) { # parent code $jobs{$chld} = $resource; } else { # child code runcmd($resource, $data); exit; # end chld, trigger $SIG{CHLD} } } sleep until @resource == $num_resources; print "ONE ROUND DONE"; last unless @data; print "RELOAD THEN PRESS ENTER: "; <>; }` [download] perl -e'$_="nwdd\x7F^n\x7Flm{{llql0}qs\x14";s/./chr(ord$&^30)/ge;print'	[reply] [d/l]

Replies are listed 'Best First'.

Re: Re: forking and ipc
by pizza_milkshake (Monk) on May 03, 2004 at 05:15 UTC

my $chld;
while (@data) {
        while (@resource) {
                last unless @data;
                my $resource = shift @resource;
                my $data = shift @data;
                if (($chld = fork()) > 0) {
                        # parent code
                        $jobs{$chld} = $resource;
                } else {
                        # child code
                        runcmd($resource, $data);
                        exit;           # end chld, trigger $SIG{CHLD}
                }
        }
        sleep until @resource == $num_resources;
        print "ONE ROUND DONE";
        last unless @data;
        print "RELOAD THEN PRESS ENTER: ";
        <>;
}
[download]

perl -e'$_="nwdd\x7F^n\x7Flm{{llql0}qs\x14";s/./chr(ord$&^30)/ge;print'

[reply]
[d/l]