Re: [apache-talk] DSO modules

[Igor Vinokurov <igor@xxxxxxxxx>]

In article <19990330155553.A18376@xxxxxxxxx> you wrote:
> Правильно ли я понимаю, что загруженные at runtime
> DSO модули не шарятся (от share) между копиями httpd
> даже в том случае если httpd имеют один конфиг?

Вот что мне ответили в comp.infosystems.www.servers.unix

---

From: "Ralf S. Engelschall" <rse@xxxxxxxxxxxxxxx>                               
Newsgroups: comp.infosystems.www.servers.unix                                   
Subject: Re: DSO                                                                
Date: 1 Apr 1999 08:35:59 GMT                                                   
Message-ID: <7dvb5f$12r2$1@xxxxxxxxxxxxxxxxxxx>                                 

Igor Vinokurov <igor@xxxxxxxxx> wrote:

> Question about DSO modules - can its code be shared between                   
> parent/child processes on systems with support dlopen/dlsym?                  
> Especially FreeBSD/Linux?                                                     

I do not exactly understand your question, but three points (I assume you're
talking about DSO modules of Apache):

1. The DSO support in Apache is always dlopen/dlsym-based, except for some
   brain-dead platforms where an emulation library is used (e.g. on AIX).

2. The code is usually always shared between the parent and forked
   child-processes, independent whether you use DSOs or not. Because Apache
   only loads DSOs into the parent and on modern Unix platforms like
   FreeBSD/Linux copy-on-write is used. So, the code segments are shared for
   DSO and non-DSO situation.

3. DSO modules are not there to safe memory (they don't).
   Their intent is to provide flexibility, i.e. you can run different Apache
   instances out of a single installation. For instance one with SSL, one
   without SSL.  One with SSL+Perl, one with only Perl, etc.  In short: You
   don't have to choose the modules under build/installation time. Instead you
   can assemble your httpd processes under run-time. But that
   hasn't anything to do with memory savings, of course.

                                       Ralf S. Engelschall
                                       rse@xxxxxxxxxxxxxxx
                                       www.engelschall.com

---

Я думаю, что Ralf S. Engelschall тут знают :)

-- 
Игорь Винокуров
Российская Торговая Система
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