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Article #7558Re: Accessing same variable from multiple threads
From: Remy Lebeau (TeamB)
Date: Wed, 19 Jan 2005 21:35
Date: Wed, 19 Jan 2005 21:35
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"Alan Bellingham" <alanb@episys.com> wrote in message news:qu9tu0hgv4gqnlvv65nqq70ua4v73jv0mu@4ax.com... > Otherwise, the writing thread may have partially updated it when > a reading thread attempts to read it. If it's a primitive, and you > only have a single processor machine with no ability to actually > execute more than one thread at a time, then I don't think you > will see thread switching in the middle of the write. That depends on not only the nature of the shared data itself, but also its alignment in memory. For instance, a 32-bit integer aligned on a 32-bit memory boundary can be read from and written to atomically, so the access can be implicitally synchronized by the CPU directly. But that is usually not the case, unless you make the extra effort to specifically set up your code to ensure that scenerio. Any other time, you usually have to provide your own synchronizing in your own code. Gambit
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X-Google-Thread: 10cc67,4809cdd9a7828fa7 X-Google-Attributes: gid10cc67,public X-Google-Language: ENGLISH,ASCII-7-bit From: "Remy Lebeau \(TeamB\)" <no.spam@no.spam.com> Newsgroups: borland.public.cppbuilder.nativeapi References: <41edea6b@newsgroups.borland.com> <41ee3727$1@newsgroups.borland.com> <41ee742e$1@newsgroups.borland.com> <41ee8f57$1@newsgroups.borland.com> <qu9tu0hgv4gqnlvv65nqq70ua4v73jv0mu@4ax.com> Subject: Re: Accessing same variable from multiple threads Date: Wed, 19 Jan 2005 13:35:39 -0800 Lines: 22 X-Priority: 3 X-MSMail-Priority: Normal X-Newsreader: Microsoft Outlook Express 6.00.2800.1409 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1409 NNTP-Posting-Host: 68.69.17.41 Message-ID: <41eed226@newsgroups.borland.com> X-Trace: newsgroups.borland.com 1106170406 68.69.17.41 (19 Jan 2005 13:33:26 -0800) Path: arc1-ca.pugleaf.net!g2news1.google.com!news2.google.com!proxad.net!212.101.4.254.MISMATCH!solnet.ch!solnet.ch!newsfeed.freenet.de!newsfeed00.sul.t-online.de!newsfeed01.sul.t-online.de!t-online.de!newsgroups.borland.com!not-for-mail