From p.dalgaard at biostat.ku.dk  Sat Jan 31 16:55:05 2009
From: p.dalgaard at biostat.ku.dk (Peter Dalgaard)
Date: Sat, 31 Jan 2009 16:55:05 +0100
Subject: [Rd] Side-effects of require() vs library() on x86_64 aka amd64
In-Reply-To: <18820.28545.87207.417437@ron.nulle.part>
References: <18817.12266.512527.675087@ron.nulle.part>	<18819.54749.999186.155947@ron.nulle.part>	<20090131145913.GI248@ziti.local>
	<18820.28545.87207.417437@ron.nulle.part>
Message-ID: <49847459.4060109@biostat.ku.dk>

Dirk Eddelbuettel wrote:
> Hi Seth,
> 
> Thanks for the follow-up.
> 
> On 31 January 2009 at 06:59, Seth Falcon wrote:
> | * On 2009-01-30 at 22:38 -0600 Dirk Eddelbuettel wrote:
> | > Turns out, as so often, that there was a regular bug lurking which is now
> | > fixed in RDieHarder 0.1.1.  But I still would like to understand exactly what
> | > is different so that --slave was able to trigger it when --vanilla,
> | > --no-save, ... did not.  
> | > 
> | > [ The library() vs require() issue may have been a red herring. ]
> | 
> | Without telling us any details about the nature of the bug you found,
> | it is difficult to speculate.  If the bug was in your C code and
> | memory related, it could simply be that the two different run paths
> | resulted in different allocation patterns, one of which triggered the
> | bug.
> 
> Yes yes and yes :)  It was in C, and it was memory related and it dealt
> getting results out of the library to which the package interfaces. 
> 
> But short of looking at the source, is there any documentation on what
> --slave does differently?
> 
> Dirk
> 

Not really (and you know where to find the sources...). But sometimes it 
only takes one memory allocation more or less to shift the effect of a 
memory bug to a completely different point in space an time.

-- 
    O__  ---- Peter Dalgaard             ?ster Farimagsgade 5, Entr.B
   c/ /'_ --- Dept. of Biostatistics     PO Box 2099, 1014 Cph. K
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[Rd] Side-effects of require() vs library() on x86_64 aka amd64
Peter Dalgaard