thanks, I am using slightly modified version of the last snippet of code, but it seems like the callback function run_on_finish() doesn't get called for SOME of the forked processes.

The processes are definitely spawned and the external commands are run, and I can see the output on STDOUT. I am spawning about 50 processes at a time, every 10 seconds. More precisely, I am spawning 1 process every 10 seconds, which then in turn forks 50 processes to do the work.

If run_on_finish() is never called, then I would think it's due to some programmatic error, but it seems to be sporadic. Which of course doesn't rule out error on my part, but probably a more subtle error that has left me a little puzzled.

Here's the simplified code structure: 

$SIG{'ALRM'} = 'sig_handler';

setitimer(ITIMER_REAL, 1, 10);

while (1){}

sig_handler{
     if ($pid = fork){

     }else{
        my $MAX    = 1000;  # just for testing
        my $pm = new Parallel::ForkManager($MAX);

        my $dbh    = DBI->connect("DBI:mysql:database=xxxxxx;host=SOME
+HOST",
                  "user", "passwd",
                  {'RaiseError' => 1});
    
        $pm->run_on_finish( 
             sub { 
                 my ($pid, $exit_code, $ident) = @_;
                 my ($check_id, $host) = $ident =~ /^(.*?) on (.*)/s;
                 insert_result(\$dbh, $host, $check_id, $exit_code);
             }
        );
        
        $pm->run_on_start(
             sub {
                 my ($pid,$ident)=@_;
                 print "** $ident started, pid: $pid\n";
             }
        );

        for(my $i=0; $i< @servers; $i++){
            my $srv_id        = $servers[$i]{id};
            my $srv_name    = $servers[$i]{name};

            for my $check_id (@{$checks{$srv_id}}){

                 $pm->start("$check_id on $srv_id") and next;
                 exec(@{$commands{$check_id}});
                 print(STDERR "$check_id on $srv_name exec failed: $!\
+n");
                 _exit($!);
            }
        }

        $dbh->disconnect();
        exit();    
     }
}

[download]

Please let me know if you have any suggestions. The reason that I am spawning a child to call Parallel:FM, is that I want to ensure that a process is spawned exactly every 10 seconds to do the work of spawning processes to run on process on X number of hosts, where X can grow depending on what it can scale to (with some experimenting). thanks.

In reply to Re^2: Forking child processes. by sojourn548
in thread Forking child processes. by sojourn548

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