#! perl -slw
use strict;
use threads;

sub t1{
    printf "%3d:t1: %s\n", threads->tid, join '|', grep defined, caller(1);
    return
}

sub t2 {
    t1();
    printf "%3d:t2: %s\n", threads->tid, ''; '|',  grep defined, caller(1);
    return
}

sub t3 {
    for( 1 .. 100 ) {
        t2();
        printf "%3d:t3: %s\n", threads->tid, join '|',  grep defined, caller(1);
    }
    return;
}

my @threads = map{ threads->create( \&t3 ) } 1 .. 100;
sleep 3;
$_->join for @threads;