Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > comp.lang.java.programmer > #24870

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

Show key headers only | View raw

On 31/07/13 16:36, taqmcg@gmail.com wrote:
> The use of Thread.stop() is strongly deprecated, but I'm a bit
> confused by the explanation given in the documentation: (e.g.,
> http://docs.oracle.com/javase/6/docs/technotes/guides/concurrency/threadPrimitiveDeprecation.html)
>
>  Because it is inherently unsafe. Stopping a thread causes it to
> unlock all the monitors that it has locked. (The monitors are
> unlocked as the ThreadDeath exception propagates up the stack.) If
> any of the objects previously protected by these monitors were in an
> inconsistent state, other threads may now view these objects in an
> inconsistent state. Such objects are said to be damaged. When threads
> operate on damaged objects, arbitrary behavior can result. This
> behavior may be subtle and difficult to detect, or it may be
> pronounced. Unlike other unchecked exceptions, ThreadDeath kills
> threads silently; thus, the user has no warning that his program may
> be corrupted. The corruption can manifest itself at any time after
> the actual damage occurs, even hours or days in the future.
>
> As I understand this, the ThreadDeath exception is treated exactly as
> any other exception -- finally blocks are honored, it can even be
> caught -- that might be thrown unexpectedly.

A method that aquires a monitor usually performs a complex task. 
Consider the removal of an element from a double-linked list for 
example. A method deleting an element would first aquire the monitor, 
then manipulate a few references, at least two. And that is simply not 
atomic. If the ThreadDeath exception is thrown after the first reference 
has been adjusted but before the second reference has been adjusted, 
then the integrity of the list is broken. You wouldn't want that to 
happen, would you? The result can be arbitrary behaviour when this list 
is subquently used.

I have not seen anybody coding in a such way, that he anticipated a 
ThreadDeath exception in every line of a synchronized block. In 
particular, I never saw the finally block that would be needed to 
restore the integrity of the list (or whatever object the method is 
working on) in case of such an exception. And I would argue, that it's 
very tricky to do too!

> E.g., if we got an
> OutOfMemoryError or we happen to  explicitly throw a RuntimeException
> we're going to see exactly the same behavior with monitors released
> progressively as we go up the stack.  It's certainly easy enough  to
> catch and rethrow the ThreadDeath in its run method if I really want
> to log it and address the one difference.

I would assume, that an OutOfMemoryError thrown in the wrong line can 
actually result in an object's integrity being broken as well. Have you 
ever programmed in such a way, that the integrity of any object will not 
be harmed by an unexpected OutOfMemoryError? Or are you, like anybody 
else, praying that it never happens?



Regards,
   Sven

Back to comp.lang.java.programmer | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread

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

csiph-web