Groups > comp.lang.java.programmer > #2690

Re: AtomicReferenceArray writes and visibility

From	markspace <-@.>
Newsgroups	comp.lang.java.programmer
Subject	Re: AtomicReferenceArray writes and visibility
Date	2011-03-31 21:58 -0700
Organization	A noiseless patient Spider
Message-ID	<in3m1d$pb9$1@dont-email.me> (permalink)
References	<in14ae$qap$1@Gaia.teknon.de> <in3jv4$1so$1@dont-email.me> <eL6dnXcySPvzxwjQnZ2dnUVZ_q2dnZ2d@posted.palinacquisition>

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On 3/31/2011 9:54 PM, Peter Duniho wrote:
> On 3/31/11 9:22 PM, markspace wrote:
>> [...]
>> Read the source code for the AtomicReferenceArray. set() doesn't use any
>> synchronization. It calls sun.misc.Unsafe#putObjectVolatile(). I don't
>> see how that's going to create a happens-before.
>
> "volatile" creates the happens-before. All writes before a volatile
> write in the same thread must be visible in a given thread after a
> volatile read in the same thread from the same location.

I didn't notice the keyword volatile there.  Did I miss it?

Regardless, the lack of any guarantees in the docs of 
AtomicReferenceArray would kill it for me.  You can't be sure how the 
implementation will change over time.

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Thread

AtomicReferenceArray writes and visibility v_borchert@despammed.com (Volker Borchert) - 2011-03-31 05:43 +0000
  Re: AtomicReferenceArray writes and visibility Peter Duniho <NpOeStPeAdM@NnOwSlPiAnMk.com> - 2011-03-31 00:52 -0700
    Re: AtomicReferenceArray writes and visibility v_borchert@despammed.com (Volker Borchert) - 2011-04-02 06:28 +0000
  Re: AtomicReferenceArray writes and visibility Kevin McMurtrie <mcmurtrie@pixelmemory.us> - 2011-03-31 20:55 -0700
  Re: AtomicReferenceArray writes and visibility markspace <-@.> - 2011-03-31 21:22 -0700
    Re: AtomicReferenceArray writes and visibility Peter Duniho <NpOeStPeAdM@NnOwSlPiAnMk.com> - 2011-03-31 21:54 -0700
      Re: AtomicReferenceArray writes and visibility markspace <-@.> - 2011-03-31 21:58 -0700
        Re: AtomicReferenceArray writes and visibility Patricia Shanahan <pats@acm.org> - 2011-03-31 22:24 -0700
          Re: AtomicReferenceArray writes and visibility markspace <-@.> - 2011-03-31 22:55 -0700
  Re: AtomicReferenceArray writes and visibility Lew <lew@lewscanon.com> - 2011-04-01 11:40 -0700

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