From: Kirk Haines <khaines@...>
Date: 2005-11-11T02:58:54+09:00
Subject: Re: Thread Safety

On Thursday 10 November 2005 10:42 am, jwesley wrote:

> 1) An exception is stored in a global variable, "$!". If multiple
> threads have exceptions thrown, is the the thread guaranteed to get
> it's own exception (not another threads) when evaluating the "$!".  (I
> know there is a work around by naming the exception.)
>
> 2) Does ruby commonly use global values to pass values...which is not
> thread safe (unless it's somehow "thread-local").

Don't use globals.  I can't think of a single instance where one needs to use 
them, though maybe someone else can.  So, if you do want to use them, use a 
mutex.synchronize block around them.

> 3) Is there any plan to use OS-level threads in Ruby 2.0?  A simple
> thread example I wrote was incredibly slow and I think it was because
> many "slow-to-return" OS calls were being made...

Yes.  OS level threads are going to be supported in Ruby 2.0.

At the current time, if one has code that is making a lot of calls which will 
block, the best alternative is to use a multiprocess model instead of a 
multithreaded model.


Kirk Haines