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Re: What is so bad aboud Thread.stop() ?

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On Thursday, August 15, 2013 8:35:39 PM UTC-4, Lew wrote:
> taq...@gmail.com wrote:
> 
> > markspace wrote:
> 
> >> Also, if you're going to be dealing with threads at all, get yourself a 
> 
> >> copy of Java Concurrency in Practice.  It's *the* state of the art for 
> 
> >> working with threads in Java.
> 
> > 
> 
> >> I'll also link to this article by its author:
> 
> >> 
> 
> >> <http://www.ibm.com/developerworks/java/library/j-jtp05236/index.html>
> 
> > 
> 
> > It's an interesting article, but I think it tends to undercut your thesis that the check for interrupt in some basic calls [I don't think most normal I/O calls are included though, just some NIO ones] means that we don't need to couple the monitoring code and the worker thread.  Since InterruptedException is a declared exception, we need to either declare it in any method that calls these, or we need to handle it in some way -- that's what Goetz is basically talking about. If you want to handle thread interrupts then you will often need to do more than swallow the interrupted exception.  Just for grins, if we consider 
> 
> 
> 
> Goetz and others point out that you should never swallow InterruptedException, but re-interrupt the 
> 

Never is a bit too strong.  The referenced article indicates that there is one circumstance under which it's OK to swallow the interrupt -- where the thread is about to terminate.  That's actually the case in the example Mark gave which swallows the exception.  But overall that right and it just emphasizes the point that reliance upon the fact that a few methods will throw an InterruptedException doesn't go very far in getting a thread to terminate.

I did get a chance to look at Java Concurrency in Practice.  It doesn't talk about Thread.stop except in a footnote that says not to use it.  But the only justification given is a reference to the very text that I found to be unconvincing at the start of this thread.  Their view of this isn't surprising.  I suspect these are the very people whose input led the class to be deprecated in the first place -- they may have written that text!  [This doesn't in any way mean to 'deprecate' their comment, just to note that it's likely not an independent statement of the badness of Thread.stop from the deprecation itself.]

Nonetheless there are some interesting tidbits to be gleaned from the their chapter on terminating threads that might be relevant to this discussion.

Overall in discussing thread interrupts they note that one needs to set up a policy for handling interrupts.  The whole chapter is addressing policies for how to handle interrupts and other terminations.  That same would surely be true for Thread.stop.  It could only be used robustly within some clear policy. 

They dismiss the need for preemptive termination of threads with:
 "The cooperative approach is required because we rarely want a task, thread, or service to stop immediately, since that could leave shared data structures in an inconsistent state."  This suggests that a stop policy might include: "we want the thread stopped immediately, and we have no further interest in any shared any data structures".

Finally, in their discussion of the handling of exceptions thrown in threads, they note that task processing threads are the only places where it is appropriate for RunTimeExceptions to be handled.  We have yet another footnote:

"There is some controversy over the safety of this technique; when a thread throws an unchecked exception, the entire application may possibly
be compromised. But the alternative, shutting down the entire application, is usually not practical."

As discussed very early in this thread, it seems like handling Thread.stop is very similar to handling RuntimeExceptions.  It's not coincidental that task managers are the primary area in which I could see Thread.stop being used effectively.  If one is capable of handling a RuntimeException in a thread, it may not be much different handling Thread.stop.

   Regards,
   Tom McGlynn

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Thread

What is so bad aboud Thread.stop() ? taqmcg@gmail.com - 2013-07-31 06:36 -0700
  Re: What is so bad aboud Thread.stop() ? Marcel Müller <news.5.maazl@spamgourmet.org> - 2013-07-31 18:31 +0200
  Re: What is so bad aboud Thread.stop() ? Arne Vajhøj <arne@vajhoej.dk> - 2013-07-31 12:35 -0400
    Re: What is so bad aboud Thread.stop() ? Lew <lewbloch@gmail.com> - 2013-07-31 14:13 -0700
      Re: What is so bad aboud Thread.stop() ? usvirtualobservatory@gmail.com - 2013-08-01 07:38 -0700
        Re: What is so bad aboud Thread.stop() ? Lew <lewbloch@gmail.com> - 2013-08-01 14:07 -0700
          Re: What is so bad aboud Thread.stop() ? Steven Simpson <ss@domain.invalid> - 2013-08-01 23:15 +0100
            Re: What is so bad aboud Thread.stop() ? taqmcg@gmail.com - 2013-08-01 16:16 -0700
              Re: What is so bad aboud Thread.stop() ? "Chris Uppal" <chris.uppal@metagnostic.REMOVE-THIS.org> - 2013-08-02 18:35 +0100
                Re: What is so bad aboud Thread.stop() ? Kevin McMurtrie <mcmurtrie@pixelmemory.us> - 2013-08-03 19:21 -0700
              Re: What is so bad aboud Thread.stop() ? Arne Vajhøj <arne@vajhoej.dk> - 2013-08-02 21:58 -0400
                Re: What is so bad aboud Thread.stop() ? taqmcg@gmail.com - 2013-08-03 05:08 -0700
  Re: What is so bad aboud Thread.stop() ? Kevin McMurtrie <mcmurtrie@pixelmemory.us> - 2013-07-31 21:09 -0700
    Re: What is so bad aboud Thread.stop() ? usvirtualobservatory@gmail.com - 2013-08-01 08:00 -0700
      Re: What is so bad aboud Thread.stop() ? Arne Vajhøj <arne@vajhoej.dk> - 2013-08-01 11:25 -0400
        Re: What is so bad aboud Thread.stop() ? Eric Sosman <esosman@comcast-dot-net.invalid> - 2013-08-01 11:49 -0400
          Re: What is so bad aboud Thread.stop() ? Arne Vajhøj <arne@vajhoej.dk> - 2013-08-02 21:51 -0400
        Re: What is so bad aboud Thread.stop() ? taqmcg@gmail.com - 2013-08-01 09:30 -0700
          Re: What is so bad aboud Thread.stop() ? markspace <markspace@nospam.nospam> - 2013-08-01 10:01 -0700
          Re: What is so bad aboud Thread.stop() ? Arne Vajhøj <arne@vajhoej.dk> - 2013-08-02 21:55 -0400
  Re: What is so bad aboud Thread.stop() ? Sven Köhler <remove-sven.koehler@gmail.com> - 2013-08-01 18:28 +0300
  Re: What is so bad aboud Thread.stop() ? "Chris Uppal" <chris.uppal@metagnostic.REMOVE-THIS.org> - 2013-08-02 18:50 +0100
    Re: What is so bad aboud Thread.stop() ? taqmcg@gmail.com - 2013-08-02 11:34 -0700
      Re: What is so bad aboud Thread.stop() ? Arne Vajhøj <arne@vajhoej.dk> - 2013-08-02 22:04 -0400
        Re: What is so bad aboud Thread.stop() ? "Chris Uppal" <chris.uppal@metagnostic.REMOVE-THIS.org> - 2013-08-03 10:10 +0100
      Re: What is so bad aboud Thread.stop() ? "Chris Uppal" <chris.uppal@metagnostic.REMOVE-THIS.org> - 2013-08-03 10:28 +0100
        Re: What is so bad aboud Thread.stop() ? taqmcg@gmail.com - 2013-08-03 05:00 -0700
          Re: What is so bad aboud Thread.stop() ? blmblm@myrealbox.com <blmblm.myrealbox@gmail.com> - 2013-08-11 17:46 +0000
            Re: What is so bad aboud Thread.stop() ? taqmcg@gmail.com - 2013-08-13 11:47 -0700
              Re: What is so bad aboud Thread.stop() ? blmblm@myrealbox.com <blmblm.myrealbox@gmail.com> - 2013-08-13 20:18 +0000
                Re: What is so bad aboud Thread.stop() ? Patricia Shanahan <pats@acm.org> - 2013-08-13 13:51 -0700
                Re: What is so bad aboud Thread.stop() ? blmblm@myrealbox.com <blmblm.myrealbox@gmail.com> - 2013-08-14 22:42 +0000
                Re: What is so bad aboud Thread.stop() ? taqmcg@gmail.com - 2013-08-13 14:10 -0700
                Re: What is so bad aboud Thread.stop() ? Lew <lewbloch@gmail.com> - 2013-08-13 15:22 -0700
                Re: What is so bad aboud Thread.stop() ? Arivald <NOSPAMarivald@interia.pl> - 2013-08-14 01:08 +0200
                Re: What is so bad aboud Thread.stop() ? markspace <markspace@nospam.nospam> - 2013-08-13 16:45 -0700
                Re: What is so bad aboud Thread.stop() ? Arivald <NOSPAMarivald@interia.pl> - 2013-08-14 08:42 +0200
                Re: What is so bad aboud Thread.stop() ? Marcel Müller <news.5.maazl@spamgourmet.org> - 2013-08-14 09:48 +0200
                Re: What is so bad aboud Thread.stop() ? taqmcg@gmail.com - 2013-08-14 08:55 -0700
                Re: What is so bad aboud Thread.stop() ? markspace <markspace@nospam.nospam> - 2013-08-14 19:10 -0700
                Re: What is so bad aboud Thread.stop() ? taqmcg@gmail.com - 2013-08-15 06:51 -0700
                Re: What is so bad aboud Thread.stop() ? Lew <lewbloch@gmail.com> - 2013-08-15 17:35 -0700
                Re: What is so bad aboud Thread.stop() ? taqmcg@gmail.com - 2013-08-16 06:30 -0700
                Re: What is so bad aboud Thread.stop() ? blmblm@myrealbox.com <blmblm.myrealbox@gmail.com> - 2013-08-14 22:43 +0000
                Re: What is so bad aboud Thread.stop() ? taqmcg@gmail.com - 2013-08-15 12:12 -0700

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