I concur. Sleeping already relinquishes the CPU, so yield is redundant and wasteful.

At least that's the theory, but it's supported by the following program using 0% CPU: 

use Time::HiRes qw( usleep );

for (;;) {
   usleep(250000);
}

[download]

Do you have any reason to believe otherwise?

Update: Screw theory, the following shows usleep does what you want. 

use strict;
use warnings;

use Time::HiRes qw( usleep time );
use threads;

{
   my $i = 0;

   my $s = time;

   my $t1 = async { usleep(250000);             };
   my $t2 = async { ++$i while $i < 50_000_000; };
   $_->join() for $t1, $t2;

   my $e = time;
   printf("%.0f\n", ($e-$s)*100000);
}

{
   my $i = 0;

   my $s = time;

   my $t1 = async {                             };
   my $t2 = async { ++$i while $i < 50_000_000; };
   $_->join() for $t1, $t2;

   my $e = time;
   printf("%.0f\n", ($e-$s)*100000);
}

[download]

In reply to Re: Perl threads: using yield() and Time::HiRes usleep() in Linux/*nix by ikegami
in thread Perl threads: using yield() and Time::HiRes usleep() in Linux/*nix by ait

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