If they run on different CPU's, then why do you have to yield() to get other threads to run, on an SMP kernel?

Update... I guess you don't. But in Coro I did have to call cede() in looping threads to let any other thread run.

This works:

use 5.20.0;
use threads;

sub loop1 { do { print "loop1\n"; sleep 1 } while 1 }
sub loop2 { do { print "loop2\n"; sleep 1 } while 1 }

my $thr1 = threads->create('loop1');
my $thr2 = threads->create('loop2');

do { print "main\n"; sleep 1 } while 1;
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This also works:

use 5.20.0;
use threads;

my $thr1 = async { do { print "loop1\n"; sleep 1 } while 1 };
my $thr2 = async { do { print "loop2\n"; sleep 1 } while 1 };

do { print "main\n"; sleep 1 } while 1;
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This does not work:

use 5.20.0;
use Coro;

async { do { print "loop1\n"; sleep 1 } while 1 }
async { do { print "loop2\n"; sleep 1 } while 1 }
do { print "main\n"; sleep 1 } while 1;
[download]