Re: Problem with large files on different OSes

From: Andreas Ericsson <ae@op5.se>
Date: May 27, 2009, 11:37 UTC
Message-ID: <4A1D2614.5060303@op5.se>
In-Reply-To: <submission.1M9Gk0-0000N8-MQ@mail.cs.st-andrews.ac.uk>

Christopher Jefferson wrote:

Show 39 quoted lines

> I recently came across a very annoying problem, characterised by the 
> following example:
> 
> On a recent ubuntu install:
> 
> dd if=/dev/zero of=file bs=1300k count=1k
> git commit file -m "Add huge file"
> 
> 
> The repository can be pulled and pushed successfully to other ubuntu 
> installs, but on Mac OS X, 10.5.7 machine with 4GB ram git pull produces:
> 
> remote: Counting objects: 6, done.
> remote: git(1533,0xb0081000) malloc: *** mmap(size=1363152896) failed 
> (error code=12)
> remote: *** error: can't allocate region
> remote: *** set a breakpoint in malloc_error_break to debug
> remote: git(1533,0xb0081000) malloc: *** mmap(size=1363152896) failed 
> (error code=12)
> remote: *** error: can't allocate region
> remote: *** set a breakpoint in malloc_error_break to debug
> remote: fatal: Out of memory, malloc failed
> error: git upload-pack: git-pack-objects died with error.
> fatal: git upload-pack: aborting due to possible repository corruption 
> on the remote side.
> remote: aborting due to possible repository corruption on the remote side.
> fatal: protocol error: bad pack header
> 
> 
> The problem appears to be the different maximum mmap sizes available on 
> different OSes. Whic I don't really mind the maximum file size 
> restriction git imposes, this restriction varying from OS to OS is very 
> annoying, fixing this required rewriting history to remove the commit, 
> which caused problems as the commit had already been pulled, and built 
> on, by a number of developers.
> 
> If the requirement that all files can be mmapped cannot be easily 
> removed, would be it perhaps be acceptable to impose a (soft?) 1GB(ish) 
> file size limit?

Most definitely not. Why should we limit a cross-platform system for the benefit of one particular developer's lacking hardware?

Such a convention should, if anything, be enforced by social policy, but not by the tool itself.

Otherwise, why not just restrict the tool that created the huge file so that it makes smaller files that fit into git on all platforms instead? (No, that wasn't a real suggestion. It was just to make the point that your suggestion for git to impose artificial limits is equally ludicrous)

-- 
Andreas Ericsson                   andreas.ericsson@op5.se
OP5 AB                             www.op5.se
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