perl主程序永远等待

我对perl比较陌生,我编写了一个程序来处理操作系统映像集上的相同操作。由于操作是相同的,所以我使用了线程。随附程序的缩小版本。问题是,主程序永远不会出现并等待。在跟踪时,我看到主程序正在等待“tee”命令。有什么我搞砸的吗?

我使用的是Perl版本5.1的CentOS 6.7,由于许多其他依赖性,我无法前进:(

#!/usr/bin/perl -w
use threads;


my $tee_pid= open my $tee, "|-", "tee mylog";
my @images = ( "image1" , "image2");

foreach my $image (@images){
$_ = async { do_ops_on_image() };
sleep ( 60 );
}

while( threads->list ) {
    for my $joinable ( threads->list( threads::joinable ) ) {
        $joinable->join;
    }
}
print "All thread completed \n";
close $tee;

sub do_ops_on_image
{
  my $time = `date`;
  my $id = threads->tid();
  sleep (120) if ( $id ==2 );
  print $tee "my $id started at $time \n";
}