Perl的线程系统如何工作? [英] How does Perl's threading system work?

问题描述

Perl的文档说: 自Perl 5.8起，使用称为解释器线程的模型进行线程编程，该模型为每个线程提供了新的Perl解释器.

在下面的程序中使用ps -Lm <pid>，我可以看到线程并行运行，即它们在不同的内核中同时运行.但是，即使有4个线程(3个和主线程)，ps aux也仅显示一个Perl进程.

Using ps -Lm <pid> with the program below I can see that threads run in parallel, i.e., they are being run at the same time in different cores. But even when there are 4 threads (3 and the main) ps aux shows only one Perl process.

1. 这是否意味着每个线程上都有一个完整的 Perl解释器?
2. Perl线程是否映射到系统线程?
3. 如果2为true，那么如何在单个进程中拥有多个Perl解释器?

1. Does this mean that there is a whole Perl interpreter on each thread?
2. Are Perl threads mapped to system threads?
3. If 2 is true, how is possible to have multiple Perl interpreters within a single process?

use threads;

$thr = threads->new(\&sub1);
$thr2 = threads->new(\&sub1);
$thr3 = threads->new(\&sub1);

sub sub1 { 
      $i = 0;
      while(true){
        $i = int(rand(10)) + $i;
      }
}


$thr->join;

推荐答案

"Perl解释器"是指执行Perl代码的环境.从用户的角度来看，主要是符号表及其中的全局变量，但它还包含许多内部变量(例如，在解析过程中使用的变量，当前操作等).

"Perl interpreter" refers to the environment in which the Perl code executes. From a user's perspective, that's mostly the symbol table and the globals therein, but it also includes a slew of internal variables (e.g. those used during parsing, the current op, etc).

1. 是的，每个线程都有一个Perl解释器.

1. Yes, there's a Perl interpreter for each thread.

是的，Perl线程是系统线程.

Yes, Perl threads are system threads.

将"Perl解释器"视为可以创建任意数量实例的类.* Perl将其称为 perlembed .

Think of "Perl interpreter" as a class of which you can make any number of instances.* Perl refers to this as Multiplicity. See perlembed for how to embed a Perl interpreter in your application.

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*—在构建Perl时需要使用-Dusemulitplicity，这是-Dusethreads所隐含的，这是向Perl中添加线程支持的方式.否则，将使用一堆全局变量而不是类".

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* — Requires the use of -Dusemulitplicity when building Perl, which is implied by -Dusethreads, which is how thread support is added to Perl. Otherwise, a whole bunch of globals are used instead of a "class".

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