Groups > comp.lang.java.programmer > #10760

Re: Question whether a problem with race conditions exists in this case

Path	csiph.com!x330-a1.tempe.blueboxinc.net!newsfeed.hal-mli.net!feeder3.hal-mli.net!newsfeed.hal-mli.net!feeder1.hal-mli.net!npeer01.iad.highwinds-media.com!news.highwinds-media.com!feed-me.highwinds-media.com!postnews.google.com!glegroupsg2000goo.googlegroups.com!not-for-mail
From	Lew <lewbloch@gmail.com>
Newsgroups	comp.lang.java.programmer
Subject	Re: Question whether a problem with race conditions exists in this case
Date	Wed, 14 Dec 2011 16:55:51 -0800 (PST)
Organization	http://groups.google.com
Lines	28
Message-ID	<23351706.113.1323910551821.JavaMail.geo-discussion-forums@yqkb10> (permalink)
References	<8bbbbee3-adcc-4f28-aff5-2e230b047401@u6g2000vbg.googlegroups.com> <jcb49r$350$1@dont-email.me> <d80833f1-8be5-4535-8391-4db8c7d41a5e@c18g2000yqj.googlegroups.com>
Reply-To	comp.lang.java.programmer@googlegroups.com
NNTP-Posting-Host	173.164.137.214
Mime-Version	1.0
Content-Type	text/plain; charset=ISO-8859-1
Content-Transfer-Encoding	quoted-printable
X-Trace	posting.google.com 1323910649 20750 127.0.0.1 (15 Dec 2011 00:57:29 GMT)
X-Complaints-To	groups-abuse@google.com
NNTP-Posting-Date	Thu, 15 Dec 2011 00:57:29 +0000 (UTC)
In-Reply-To	<d80833f1-8be5-4535-8391-4db8c7d41a5e@c18g2000yqj.googlegroups.com>
Complaints-To	groups-abuse@google.com
Injection-Info	glegroupsg2000goo.googlegroups.com; posting-host=173.164.137.214; posting-account=CP-lKQoAAAAGtB5diOuGlDQk0jIwmH0T
User-Agent	G2/1.0
X-Google-Web-Client	true
Xref	x330-a1.tempe.blueboxinc.net comp.lang.java.programmer:10760

Show key headers only | View raw

Saxo wrote:
>>      When you change the shared AtomicBoolean, some threads executing
>> get() may have already observed the old value and may have decided
>> which value to return based on that now-outdated observation.  So yes,
>> there's a race: It is possible for get() to return an old value after
>> the AtomicBoolean changes from true to false, or a new value after it
>> changes from false to true.
> 
> Oh shit, of course! I have thought about it. First though was to call
> 
> if(useNewValue.get()) {
>     // ...
> }
> 
> that often till it returns the same value. But useNewValue could
> change just thereafter. So you would have to call this infinitely
> often till you are sure you get the right value. Obviously, this
> doesn't work. Then I forgot about the issue.
> 
> Thanks for the hint. Now I have to think how to solve this ...

Bearing in mind that you don't need, and shouldn't use, an 'AtomicBoolean' for
this in the first place.

-- 
Lew

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

Thread

Question whether a problem with race conditions exists in this case Saxo <saxo123@gmx.de> - 2011-12-14 09:07 -0800
  Re: Question whether a problem with race conditions exists in this case Andreas Leitgeb <avl@gamma.logic.tuwien.ac.at> - 2011-12-14 17:53 +0000
    Re: Question whether a problem with race conditions exists in this case Lew <lewbloch@gmail.com> - 2011-12-14 10:44 -0800
      Re: Question whether a problem with race conditions exists in this case Daniel Pitts <newsgroup.nospam@virtualinfinity.net> - 2011-12-14 10:54 -0800
      Re: Question whether a problem with race conditions exists in this case Andreas Leitgeb <avl@gamma.logic.tuwien.ac.at> - 2011-12-14 21:15 +0000
        Re: Question whether a problem with race conditions exists in this case Tom Anderson <twic@urchin.earth.li> - 2011-12-15 14:58 +0000
          Re: Question whether a problem with race conditions exists in this case Saxo <saxo123@gmx.de> - 2011-12-15 08:40 -0800
          Re: Question whether a problem with race conditions exists in this case Gene Wirchenko <genew@ocis.net> - 2011-12-15 11:55 -0800
            Re: Question whether a problem with race conditions exists in this case Tom Anderson <twic@urchin.earth.li> - 2011-12-16 14:06 +0000
              Re: Question whether a problem with race conditions exists in this case Gene Wirchenko <genew@ocis.net> - 2011-12-16 10:09 -0800
    Re: Question whether a problem with race conditions exists in this case Saxo <saxo123@gmx.de> - 2011-12-14 11:47 -0800
  Re: Question whether a problem with race conditions exists in this case Daniel Pitts <newsgroup.nospam@virtualinfinity.net> - 2011-12-14 10:53 -0800
    Re: Question whether a problem with race conditions exists in this case Saxo <saxo123@gmx.de> - 2011-12-14 11:54 -0800
      Re: Question whether a problem with race conditions exists in this case Daniel Pitts <newsgroup.nospam@virtualinfinity.net> - 2011-12-15 16:38 -0800
        Re: Question whether a problem with race conditions exists in this case Saxo <saxo123@gmx.de> - 2011-12-15 23:01 -0800
          Re: Question whether a problem with race conditions exists in this case Daniel Pitts <newsgroup.nospam@virtualinfinity.net> - 2011-12-16 09:34 -0800
            Re: Question whether a problem with race conditions exists in this case Saxo <saxo123@gmx.de> - 2011-12-17 11:55 -0800
              Re: Question whether a problem with race conditions exists in this case Saxo <saxo123@gmx.de> - 2011-12-19 05:33 -0800
  Re: Question whether a problem with race conditions exists in this case Lew <lewbloch@gmail.com> - 2011-12-14 11:04 -0800
    Re: Question whether a problem with race conditions exists in this case Saxo <saxo123@gmx.de> - 2011-12-14 12:32 -0800
      Re: Question whether a problem with race conditions exists in this case markspace <-@.> - 2011-12-14 14:13 -0800
        Re: Question whether a problem with race conditions exists in this case Eric Sosman <esosman@ieee-dot-org.invalid> - 2011-12-14 17:44 -0500
          Re: Question whether a problem with race conditions exists in this case Saxo <saxo123@gmx.de> - 2011-12-14 14:50 -0800
            Re: Question whether a problem with race conditions exists in this case markspace <-@.> - 2011-12-14 15:26 -0800
      Re: Question whether a problem with race conditions exists in this case Lew <lewbloch@gmail.com> - 2011-12-15 01:34 -0800
    Re: Question whether a problem with race conditions exists in this case Andreas Leitgeb <avl@gamma.logic.tuwien.ac.at> - 2011-12-14 21:38 +0000
  Re: Question whether a problem with race conditions exists in this case Eric Sosman <esosman@ieee-dot-org.invalid> - 2011-12-14 16:26 -0500
    Re: Question whether a problem with race conditions exists in this case Saxo <saxo123@gmx.de> - 2011-12-14 13:57 -0800
      Re: Question whether a problem with race conditions exists in this case Eric Sosman <esosman@ieee-dot-org.invalid> - 2011-12-14 18:05 -0500
        Re: Question whether a problem with race conditions exists in this case Saxo <saxo123@gmx.de> - 2011-12-14 23:25 -0800
          Re: Question whether a problem with race conditions exists in this case Saxo <saxo123@gmx.de> - 2011-12-14 23:28 -0800
      Re: Question whether a problem with race conditions exists in this case Tom Anderson <twic@urchin.earth.li> - 2011-12-15 14:44 +0000
        Re: Question whether a problem with race conditions exists in this case Lew <lewbloch@gmail.com> - 2011-12-16 08:27 -0800
          Re: Question whether a problem with race conditions exists in this case Daniel Pitts <newsgroup.nospam@virtualinfinity.net> - 2011-12-16 09:41 -0800
            Re: Question whether a problem with race conditions exists in this case Tom Anderson <twic@urchin.earth.li> - 2011-12-16 18:51 +0000
          Re: Question whether a problem with race conditions exists in this case Tom Anderson <twic@urchin.earth.li> - 2011-12-16 18:50 +0000
    Re: Question whether a problem with race conditions exists in this case Saxo <saxo123@gmx.de> - 2011-12-14 14:13 -0800
      Re: Question whether a problem with race conditions exists in this case Lew <lewbloch@gmail.com> - 2011-12-14 16:55 -0800

csiph-web