From: khaines@...
Date: 2006-09-05T17:25:00+09:00
Subject: Re: The real difference between Mutex and Sync

On Tue, 5 Sep 2006, Kent Sibilev wrote:

> This patch will make Mutex a bit slower, but much better in terms of
> garbage collection:
>
> Index: lib/thread.rb
> ===================================================================
> RCS file: /src/ruby/lib/thread.rb,v
> retrieving revision 1.16.2.2
> diff -r1.16.2.2 thread.rb
> 99c99
> <       @waiting.push Thread.current
> ---
>>       @waiting.unshift Thread.current
> 115c115
> <       t = @waiting.shift
> ---
>>       t = @waiting.pop

While I am not benchmarking with performance in mind, that change doesn't 
seem to have any significant effect on overall speed, which doesn't 
surprise me.  Speed-wise, it is just flipping the location of the 
expensive array operation from the unlock to the lock.

And yes, that simple change does seem to make a significant difference, 
because pop will realloc the array.


Kirk Haines