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Groups > comp.lang.java.programmer > #10674

Re: Volatile keyword

From markspace <-@.>
Newsgroups comp.lang.java.programmer
Subject Re: Volatile keyword
Date 2011-12-12 10:00 -0800
Organization A noiseless patient Spider
Message-ID <jc5ffc$28s$1@dont-email.me> (permalink)
References <41fa02ff-3f20-41bc-90d9-c3f7d3651fbf@n6g2000vbg.googlegroups.com>

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On 12/12/2011 4:51 AM, raphfrk@gmail.com wrote:

> Effectively, does the CPU lock the entire 64-bits for the long when
> doing the write update, and so other threads either seen the updated
> value or the old value?


I don't like the word "lock" here because it implies something that 
probably isn't happening.  I think that volatile, even for long and 
double, is specified to be much lighter weight than a lock.

The spec that Lew referred to says they are "atomic" and doesn't mention 
"lock."  I think of them that way, myself, in addition to "light weight" 
as opposed to the more heavy actual lock.

volatile long === light weight & atomic.

(=== here meant to mean "defined to be.")

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Thread

Volatile keyword "raphfrk@gmail.com" <raphfrk@gmail.com> - 2011-12-12 04:51 -0800
  Re: Volatile keyword Andreas Leitgeb <avl@gamma.logic.tuwien.ac.at> - 2011-12-12 14:31 +0000
    Re: Volatile keyword "raphfrk@gmail.com" <raphfrk@gmail.com> - 2011-12-12 06:52 -0800
  Re: Volatile keyword Lew <lewbloch@gmail.com> - 2011-12-12 06:34 -0800
  Re: Volatile keyword markspace <-@.> - 2011-12-12 10:00 -0800
    Re: Volatile keyword Tom Anderson <twic@urchin.earth.li> - 2011-12-12 18:41 +0000
      Re: Volatile keyword Patricia Shanahan <pats@acm.org> - 2011-12-12 11:43 -0800
    Re: Volatile keyword Roedy Green <see_website@mindprod.com.invalid> - 2011-12-12 11:15 -0800
      Re: Volatile keyword Robert Klemme <shortcutter@googlemail.com> - 2011-12-13 08:37 +0100
        Re: Volatile keyword Peter Duniho <NpOeStPeAdM@NnOwSlPiAnMk.com> - 2011-12-12 23:54 -0800
          Re: Volatile keyword Robert Klemme <shortcutter@googlemail.com> - 2011-12-14 19:39 +0100
            Re: Volatile keyword Daniel Pitts <newsgroup.nospam@virtualinfinity.net> - 2011-12-14 10:59 -0800
            Re: Volatile keyword Patricia Shanahan <pats@acm.org> - 2011-12-14 11:00 -0800
              Re: Volatile keyword Robert Klemme <shortcutter@googlemail.com> - 2011-12-14 22:35 +0100
  Re: Volatile keyword Roedy Green <see_website@mindprod.com.invalid> - 2011-12-12 10:55 -0800

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