为什么会打印 12 次？

我正在学习Perl的多线程。我的代码：

use warnings;
use threads;
use threads::shared;

$howmany = 10;
$threads = 5;

$to = int($howmany / $threads);

for (0 .. $threads) {$trl[$_] = threads->create(\&main, $_);}
for (@trl) {$_->join;}

sub main {
    for (1 .. $to) {
        print "test\n";
    }
}

exit(0);

我想打印这个词test $howmany次在$threads线程。 这段代码打印test12次。哪里有问题？

我可以建议一种替代方法吗？

use strict;
use warnings;

use threads       ;#qw( async );
use Thread::Queue qw( );

my $num_workers    = 5;
my $num_work_units = 10;

my $q = Thread::Queue->new();

# Create workers
my @workers;
for (1..$num_workers) {
   push @workers, async {
      while (defined(my $unit = $q->dequeue())) {
         print("$unit\n");
      }
   };
}

# Create work
for (1..$num_work_units) {
   $q->enqueue($_);
}

# Tell workers they are no longer needed.
$q->enqueue(undef) for @workers;

# Wait for workers to end
$_->join() for @workers;

优点：

• 更具可扩展性
• 即使 $num_work_units / $num_workers 不是整数也可以工作。
• 不假设所有工作单元需要相同的时间来完成。

Output:

1
5
2
8
9
10
7
3
4
6