Keeping multiple threads running.

[travs69]

Ok.. I have this working code

use Threads;

$process_this_many = "100";
$max_threads = "20";
$worker = 0;

while ($worker <= $process_this_many) {
    for ($x = 1; $x <= $max_threads && $worker <= $process_this_many; $x++) {   
        $thr = threads->new(\&sub1, "$x", "$worker");
        print "Start $x $worker\n";
        $worker++;
    }

# Loop through all the threads 
    foreach $thr (threads->list) { 
        # Don't join the main thread or ourselves 
        if ($thr->tid && !threads::equal($thr, threads->self)) {
            $data = $thr->join;
            print "$data\n";
        }
    }
}

sub sub1 {
    $in = shift @_;
    $in2 = shift @_;
    sleep 1;
    return "Finish $in $in2";
}

The problem with it is that if one of the threads gets hung it seems to block on the join and will hold up everything till it clears.

What I am trying to do is keep X number of threads running all the time regardless of how long it takes a single one to complete. I normally use Parallel::Forkmanager which does this very well but it is for forking and not for threads.

I think I can replicate it by using threads::shared and doing some kind of signaling through a shared variable that I can check with out blocking. It might even be possible to just detach the threads and write the results back to shared variable, but I thought I would post here and see if someone else already knows of a good solution.

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Travis - Those Who Say It Cannot Be Done Are Usually Interrupted by Someone Else Doing It; Give the wrong symptoms, get the wrong solutions;

 

[Kirsle]

You can use "detach" instead of "join". It doesn't work exactly the same way though... once you detach a thread, you can't join it, and when it exits, whatever it returns is just discarded (detach = forget about the thread but let it run as long as it wants to, whereas join = stop and wait for the thread to finish and return something).

Once you detach a thread, shared variables would probably be needed to communicate, since the thread is "forgotten about" now.

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[travs69]

I was thinking about using detach.. the problem is then the threads->list(); doesn't return anything. I was trying to use that to determine how many threads were currently running. I figured I could use shared variables to figure out the status of each thread if it was needed (I normally used a hash in memory to communicate between my forked process normally.. but Forkmanager handles the control of them).

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Travis - Those Who Say It Cannot Be Done Are Usually Interrupted by Someone Else Doing It; Give the wrong symptoms, get the wrong solutions;