Mailing-List: contact dev-help@httpd.apache.org; run by ezmlm
Precedence: bulk
Reply-To: dev@httpd.apache.org
Received-SPF: pass (hermes.apache.org: domain of luca.regini@gmail.com
 designates 64.233.170.203 as permitted sender)
DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws;
        s=beta; d=gmail.com;
        h=received:message-id:date:from:reply-to:to:subject:in-reply-to:mime-version:content-type:content-transfer-encoding:references;
        b=f1kKTVOL9o+M5sIApLYY43xKKbzFItCYCeck4p7Qj0EY1OtW5Lm/2ZG+xoNjwuCdeieekOkUWh+JfEIgymb8ykL536pJrqLt+2+j0ed2XqnUypTn8B5IznuYaVM2oSQQYDQ+uujI6H7T+VVNGqejYYR1nUfdYODEJbmevq+JeCE=
Message-ID: <64077c2805030909485256c3dd@mail.gmail.com>
Date: Wed, 9 Mar 2005 18:48:31 +0100
From: luca regini <luca.regini@gmail.com>
Reply-To: luca regini <luca.regini@gmail.com>
To: dev@httpd.apache.org
Subject: Re: Mod_MEM_cache doesn't use Pools to allocate cache objects???
In-Reply-To: <422DC00A.3000708@apache.org>
Mime-Version: 1.0
Content-Type: text/plain; charset=US-ASCII
Content-Transfer-Encoding: 7bit
References: <64077c2805030803253052d927@mail.gmail.com>
	 <422DC00A.3000708@apache.org>

I am going to use shared memory. I found a very good example in the
ssl_scache_shmht.c file. This implementation has everything i need of.
Now i am just working to remove dependencies that this code has on
other mod_ssl files, so to provide a generic
shared memory cache table object. I can release the source code to the
group if there is some interest in it. If i manage to build a generic
solution for the web service caching module i will release this source
code also.

Luca


On Tue, 08 Mar 2005 16:08:58 +0100, Matthieu Estrade
<mestrade@apache.org> wrote:
> luca regini wrote:
> 
> > Taking a look at mod_mem_cache source code i have seen that it doesn't
> > use pools to allocate cache objects but i does so by means of
> > reference counting and simple calloc/free calls. I  have also seen
> > that this module requires a Threaded apr to work.
> >
> If you use prefork, each child is a fork and has it's own memory space,
> so you are unable to share data between child -> bad idea
> The way you can do is code a cache module using shared memory but in
> this case, shm and rmm are not using pools, and i think there will be
> performances issues.
> 
> It depend on what you want to do with your cache module. Actually, in a
> threaded mpm, each child and the threads inside are sharing common data.
> So you have duplicated cache data in each forked child. The performance
> depend on how you setup your server. low child number and high thread
> number = few request on backend and only few duplicated data.
> 
> Coding a cache module using shared memory is huge work.
> Good luck if you choose to do it
> 
> Matthieu
> 
>