perl – 简单的open3示例不起作用

我为master写了这段代码：

#!/usr/bin/env perl

use strict;
use warnings;

use IPC::Open3;

my @children;

for my $i ( 0 .. 4 ) {
    print "Master: " . $i . ",I summon youn";

    $children[$i] = {};

    $children[$i]->{'pid'} = open3( my $CH_IN,my $CH_OUT,my $CH_ERR,'perl child.pl -i ' . $i );

    $children[$i]->{'_STDIN'}  = $CH_IN;
    $children[$i]->{'_STDOUT'} = $CH_OUT;
    $children[$i]->{'_STDERR'} = $CH_ERR;

    my $line = readline $children[$i]->{'_STDOUT'};
    print $line ;

}

print "Master: Go fetch me the sacred crownn";

for my $i ( 0 .. 4 ) {
    $children[$i]->{'_STDIN'}->write("fetch the sacred crownn");
    my $line = readline $children[$i]->{'_STDIN'};
    print $line ;
}

print "Master: Thanks. Now die!!!n";

for my $i ( 0 .. 4 ) {
    $children[$i]->{'_STDIN'}->write("die !!n");
    my $line = readline $children[$i]->{'_STDIN'};
    print $line ;
}

而这一个给孩子：

#!/usr/bin/env perl

use Getopt::Long ;

my $cmdline_id ;

GetOptions ('i=s' => $cmdline_id) ;

my $id = $cmdline_id ;

exit 1 if !defined $id ;

print "I am $id,and I am awakenn" ;

while(<STDIN>) {
    print STDOUT $id . ': Master ask me to ' . $_ ;

    if ($_ =~ /exit/oi) {
        exit 0 ;
    }
}

但是当我启动大师时,他只是在阅读孩子的回答时挂了.

关于我做错了什么,为什么？