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

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In article <7cb96188-91ce-4c2b-ace8-5eeb1b30815e@googlegroups.com>,
 <taqmcg@gmail.com> wrote:
> On Sunday, August 11, 2013 1:46:49 PM UTC-4, blmblm @ myrealbox. com wrote:
> > In article <ede0c691-85eb-4977-8644-27078248ed9d@googlegroups.com>,
> > 
> >  <taqmcg@gmail.com> wrote:
> > 
> > ...
> > > You can use objects that are readonly to the stoppable thread to send
> > > information to that thread, and use objects that are read by the
> > > monitor (or other threads) only after the thread has successfully
> > > finished (or at least completed the tasks during which it may be
> > > stopped) to get information back.  The fact that I might have stopped
> > > the thread in some circumstances doesn't mean I can't use objects
> > > created by it when I do let it finish.
> > 
> > 
> > That *sounds* plausible ....  But it occurs to me that assigning values
> > to variable is no longer a simple matter -- with smart compilers and
> > caches and so forth, it's hard to be sure when the value will actually
> > be visible to other threads, which is presumably why the Java memory
> > model (with its "happens before" and so forth) exists.  Can someone who
> > knows that model comment on how it might apply here?
> > 
> > 
> > B. L. Massingill
> > 
> It's certainly true that the memory model is abstruse, but that's true of
> interthread communications generally and not specific to killed threads.


Agreed.  (Do I seem to be saying otherwise?)  Indeed, that's
the point I was trying to make in saying "that's why the Java
memory model exists" -- meaning that without a model, it would
be difficult if not impossible to say anything meaningful about
when one could rely on values being visible to other threads.

> 
> If I have an object that is mutable by a thread that I might kill at some
> point, it would be pretty nifty if the fact that the thread was going to be
> killed in the future affected it before I killed it...a thiotimoline thread!


Um, I don't get the connection between this and what I wrote.  ?


> And after the monitor kills a thread, it seems like discarding all
> potentially mutated objects should be a pretty robust way to limit the
> effects.  
> 


Um, yes ....  So you're saying if thread A kills thread B, to be
safe thread A should also discard any objects potentially mutated
by thread B?


> 
> But I'd agree that if there is a third thread involved, things get a lot more
> complex -- though again that's true of thread communication generally.
> 


Third thread?  Now I'm really confused.


But to get back to your presumably-safe scenario, in which thread B
finishes normally.  It seems reasonable to assume that all values
assigned in thread B should then be visible to other threads.
What I'm wondering, though, is whether that's explicitly required
by the Java memory model.  (Yeah, yeah, really I should probably
just go read up on the memory model myself, but I thought someone
else might know, and that this might be an interesting point to
raise anyway.)


> 
>     Tom McGlynn
> 
> 
> might be killed in the future could affect it before I kill it
> 

-- 
B. L. Massingill
ObDisclaimer:  I don't speak for my employers; they return the favor.

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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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