I wonder if sleep is broken or if the box is busy or delays coming from Windows anti-malware? Looking at tests 4, 5, and 8.

perl -Ilib t/05_mce_child.t
...
ok 2 - spawning asynchronously
ok 3 - check for unique pids 
ok 4 - check list_running
ok 5 - check list_joinable
ok 6 - check list
ok 7 - check pending
ok 8 - check is_running child1
ok 9 - check is_joinable child1
ok 10 - check is_running child2
ok 11 - check is_joinable child2
ok 12 - check is_running child3
ok 13 - check is_joinable child3
...
[download]

Is there an alternative to sleep on the Windows platform, ensuring delay before the workers exit?

{
   my ( $cnt, @list, %pids, %ret ); local $_;
   my ( $come_then_i_pray ) = ( "さあ、私&#123
+99;祈る" . "Ǣ" );

   ok( 1, "spawning asynchronously" );             # test 2

   MCE::Child->create( sub { sleep 1; sleep 1; "$come_then_i_pray $_" 
+} ) for ( 1..3 );

   %pids = map { $_ => undef } MCE::Child->list_pids;
   is ( scalar( keys %pids ), 3, 'check for unique pids' ); # test 3

   @list = MCE::Child->list_running;
   is ( scalar @list, 3, 'check list_running' );   # test 4

   @list = MCE::Child->list_joinable;
   is ( scalar @list, 0, 'check list_joinable' );  # test 5

   @list = MCE::Child->list;
   is ( scalar @list, 3, 'check list' );           # test 6
   is ( MCE::Child->pending, 3, 'check pending' ); # test 7

   $cnt = 0;

   for ( @list ) {
      ++$cnt;
      is ( $_->is_running, 1, 'check is_running child'.$cnt );    # te
+sts 8, 10, 12
      is ( $_->is_joinable, '', 'check is_joinable child'.$cnt ); # te
+sts 9, 11, 13
   }

   $cnt = 0;

   for ( @list ) {
      ++$cnt; $ret{ $_->join } = 1;
      is ( $_->error, undef, 'check error child'.$cnt );
   }

   is ( scalar keys %ret, 3, 'check for unique values' );

   for ( sort keys %ret ) {
      my $id = chop; s/ $//;
      is ( $_, $come_then_i_pray, "check for utf8 string $id" );
   };
}
[download]

Update 1: I have an idea to not use sleep. Instead, I will have workers read a channel. The manager process will notify workers to exit after completing tests list_running, list_joinable, list, pending, is_running, and is_joinable.

Update 2: Released MCE 1.883 on meta::cpan