multithreading - 从线程访问包变量

Question

我在从线程访问包变量时遇到问题。这是一个大项目，所以我将尝试提取代码的相关部分。

我将线程模块和 Moose 用于 OO 部分。

our $thread2;

around 'new' => sub {
  [...]
  threads->create( \&_thread1Func, $shared_self );
  if (!$thread2) {
    $thread2 = threads->create( \&_thread2Func, $shared_self );
    $thread2->detach();
  }
}

sub _thread1Func {
  $thread2->kill('SIGUSR1');
}

sub _thread2Func {
  $SIG{'USR1'} = sub { [...] };
  while (1) {
    sleep 5;
    [...]
  }
}

我收到以下错误:

Thread N terminated abnormally: Can't call method "kill" on an undefined value at XXXX.pm line n.

与 n指向 $thread2->kill('SIGUSR1'); 行

我在想用 our 声明 $thread2使其从整个包装中可见。

知道发生了什么吗？

Answer 1

如 perldoc threads 中所述:

Since Perl 5.8, thread programming has been available using a model called interpreter threads which provides a new Perl interpreter for each thread, and, by default, results in no data or state information being shared between threads.

our “为当前包中同名的包变量创建词法别名，以在当前词法范围内使用。”

这并不意味着它创建了一个在线程之间共享的变量。为此，您需要 threads::shared .但是，请注意:

This module supports the sharing of the following data types only: scalars and scalar refs, arrays and array refs, and hashes and hash refs.

你的代码对我来说看起来很麻烦。如果您解释为什么要这样做，我们可能会提供更具体的帮助。

以下可能会做一些接近你想要的事情:

#!/usr/bin/env perl

use strict;
use warnings;

use threads;
use threads::shared;

my $thread2_tid :shared;

sub myfunc {
    threads->create(\&_thread1Func);
    if (!$thread2_tid) {
        my $thread2 = threads->create(\&_thread2Func);
        $thread2_tid = $thread2->tid;
    }
}

sub _thread1Func {
    while (1) {
        next unless defined $thread2_tid;
        last if $thread2_tid == -1;
        my $thread2 = threads->object($thread2_tid);
        $thread2->kill('SIGUSR1');
        sleep 1;
    }
}

sub _thread2Func {
    local $SIG{'USR1'} = sub { print "SIGUSR1 received\n" };
    local $| = 1;
    while (1) {
        sleep 1;
        print '.';
        if (5 < time - $^T) {
            $thread2_tid = -1;
            last;
        }
    }
}

myfunc();
$_->join for threads->list;