Question

Consider the following code:

for (my $i = 0; $i < $threadCount; $i++) {

    if($isResumed) {

        # TODO: load stats from DB      
    }
    else {

        $stats->{workers}->{$i}        = &share({});            
        $stats->{workers}->{$i}->{tid} = undef; 
        $stats->{workers}->{$i}->{foo} = "bar";
        $stats->{workers}->{$i}->{abc} = 123;                               
    }

    # create the worker thread
    my $thr = threads->create(\&worker);    
    # TODO: find a way to store the TID in the $i slot. why have two differetn IDs? 
    $stats->{workers}->{$i}->{tid} = $thr->tid();
}

I am using the $stats hash to hold data that should be shared between threads, as well as data about what each thread is doing. The problem I have is that I would like to reference the thread data in this hash based on the TID, not an arbitrary value assigned by $i in the loop.

When I create the thread, the work starts immediately, but it cannot start its work until the hash values are set. So, if I do:

$thr = threads->create(\&worker);
$stats->{workers}->{$thr->tid()} = &share({});

It will not work because not all the data it needs is set yet.

So basically, is there a way for me to create a thread, but defer it from running its code until I specifically tell it to? Something like:

$thr = threads->create(\&worker);
$stats->{workers}->{$thr->tid()} = &share({});
$thr->start();

Answer 1

In the end, after reviewing my code; I realized that I was over complicating it, and did not truly need to know the TIDs.

I ended up just passing the relevant data to the worker subroutine during the create statement.

That being said though, People who come across this question should take a look at Jean’s answer, as it appears to be a promising solution to my original problem.