如何在主线程中让一个子线程退出？

sclouder

使用了use threads;多线程模式，在实际的编码中，有一个让子线程退出的操作，我在主线程中使用$thr->kill('KILL')->detach();这种模式让指定的子线程退出，但在子线程退出后，主线程会也会退出，并报Signal SIGKILL received, but no signal handler set.，但是我希望主线程不要退出，该怎么做呢？多谢

zhlong8

threads 的文档说的很清楚啊

EXITING A THREAD

The usual method for terminating a thread is to return EXPR from the entry point function with the appropriate return value(s).

    * threads->exit()

      If needed, a thread can be exited at any time by calling threads->exit() . This will cause the thread to return undef in a scalar context, or the empty list in a list context.

      When called from the main thread, this behaves the same as exit(0).
    * threads->exit(status)

      When called from a thread, this behaves like threads->exit() (i.e., the exit status code is ignored).

      When called from the main thread, this behaves the same as exit(status).
    * die()

      Calling die() in a thread indicates an abnormal exit for the thread. Any $SIG{__DIE__} handler in the thread will be called first, and then the thread will exit with a warning message that will contain any arguments passed in the die() call.
    * exit(status)

      Calling exit EXPR inside a thread causes the whole application to terminate. Because of this, the use of exit() inside threaded code, or in modules that might be used in threaded applications, is strongly discouraged.

      If exit() really is needed, then consider using the following:

         1. threads->exit() if threads->can('exit'); # Thread friendly
         2. exit(status);

    * use threads 'exit' => 'threads_only'

      This globally overrides the default behavior of calling exit() inside a thread, and effectively causes such calls to behave the same as threads->exit() . In other words, with this setting, calling exit() causes only the thread to terminate.

      Because of its global effect, this setting should not be used inside modules or the like.

      The main thread is unaffected by this setting.
    * threads->create({'exit' => 'thread_only'}, ...)

      This overrides the default behavior of exit() inside the newly created thread only.
    * $thr->set_thread_exit_only(boolean)

      This can be used to change the exit thread only behavior for a thread after it has been created. With a true argument, exit() will cause only the thread to exit. With a false argument, exit() will terminate the application.

      The main thread is unaffected by this call.
    * threads->set_thread_exit_only(boolean)

      Class method for use inside a thread to change its own behavior for exit().

      The main thread is unaffected by this call.

sclouder

我是想在主线程中让子线程退出，而不是在子线程中自行退出，上述有函数符合这个要求吗？

zhlong8

我是想在主线程中让子线程退出，而不是在子线程中自行退出，上述有函数符合这个要求吗？
sclouder 发表于 2011-06-10 09:55

    抱歉是我没看清楚，你设个 handler 不就行了？把 SIGUSR1 设成退出当前线程

sclouder

好，我来试一下

zhlong8

回复 5# sclouder


    文档中有个很清晰的示例

   1. use threads;
   2.
   3. sub thr_func
   4. {
   5. # Thread 'cancellation' signal handler
   6. local $SIG{'KILL'} = sub { threads->exit(); };
   7.
   8. ...
   9. }
  10.
  11. # Create a thread
  12. my $thr = threads->create('thr_func');
  13.
  14. ...
  15.
  16. # Signal the thread to terminate, and then detach
  17. # it so that it will get cleaned up automatically
  18. $thr->kill('KILL')->detach();

sclouder

真的非常感谢对这个问题的细致回答，你的方法我试验成功了，不过在使用threads中还碰到一个问题，子线程退出后一段时间会报错：
Use of uninitialized value in null operation during global destruction.
请问这个错误一般是怎么引起的？

zhlong8

真的非常感谢对这个问题的细致回答，你的方法我试验成功了，不过在使用threads中还碰到一个问题，子线程退出 ...
sclouder 发表于 2011-06-10 10:37

    线程结束的时候需要释放内存，释放的时候出错了。这方面经验不多，不过看高手们的意思这个问题应该无解了