From: Markus Schirp <mbj@...>
Date: 2009-09-21T02:57:38+09:00
Subject: Re: Thread-safe FileUtils.cd

The current working process is a global property of the underlaying 
system process.

A system Process has one currency working directory, not two, or more.

You can do your directory / filename calculations, using the absolute 
directory path, without any race conditions.

--

Markus


James Coglan wrote:
> Hi all,
> 
> I have a build tool that I've written in Ruby that uses this construct to
> enter a directory, perform some long-running (several seconds) tasks then
> exit back to the original working directory:
> 
> FileUtils.cd(dir) do
>   # expensive operations
> end
> 
> Now I'm trying to write another tool that uses this build library to run
> several builds at once in different Threads. Problem is, the FileUtils.cd
> commands overlap and conflict with each other, causing the builds to fail. I
> have a lot of code already out in production that relies on this directory
> being set correctly (users can write hooks into the build system, and these
> hooks assume a certain working directory), so I can't remove the cd() call.
> 
> My question is, is there a way of setting the working directory on a
> per-thread basis, or is it a global property of the Ruby process that cannot
> be made thread-safe?
> 
> Cheers,
> James
>