Re: [Openinteract-dev] Using FastCGI as development plaftorm

[<an...@io...>]

Perrin Harkins wrote:
> I don't know anyone who compiles mod_perl as DSO.  There are clear
> warnings not to do that.

Oh that is probably true. I just checked and the Debian (in fact sadly 
Ubuntu at the moment) apache-perl package has Perl statically compiled 
instead of a DSO - and it _still_ did all of the initializations twice 
with OI2. You can verify if this applies to you by looking at the OI2 
log. The memory consuming loop in shutdown is also happening on the same 
server if OI2 has served at least one request.

> What does this mean?  That it picks up module changes?  Apache::Reload
> does that too.

I'm not sure if Apache::Reload works with OI2 very well since at least 
the Actions are cached & cloned by OI2. Also OI2 uses lots of 
configuration files which determine behaviour and autogenerate modules, 
which are naturally not reloaded by Apache::Reload. Anyway this is just 
speculation but I think I'm not far from the truth..

> You can easily tell apache how many processes it should run on your
> development server.  A FastCGI server intended for production will
> certainly run more than one process.

Well by development I did mean really just development, not production. 
We run OI2 with mod_perl on our production servers and continue to do so 
also in the future, but the beauty of OI2 is that it really doesn't 
matter which one of the options you use for development. At least for me 
FastCGI seems to speed up the development process quite a lot.. Or at 
least it feels like that ;)

Anyway this is not really an issue when developing since you barely even 
notice it (even though I have noticed almost doubled execution times on 
the first request of a child, but this might be affected by many other 
things also) - the other ones weight a lot more when choosing the 
platform for development.

But to clarify the situation I'm talking about: It doesn't matter how 
many child processes you use with Apache, they all are forked from the 
main process and share almost all of their static memory with the parent 
process until the memory becomes dirty and has to be copied to the 
child's own pool. So even if you would run only one child process, you 
would still have to copy lots of memory on the first request. Memory 
copying itself is not such an expensive task, but with large codebases 
and long execution paths like with OI2, the copying is done quite many 
separate times.

By the way if somebody wants to inspect the OI2 execution trail and how 
long each of the stages take, you can change conf/log4perl.conf to use 
DEBUG for log4perl.logger.OI2 and add SSS to the ConversionPattern in 
the end ( to %d{HH:mm:ss:SSS} ) to see millisecond timestamps on all log 
entries. All of the logging adds something like 20% to the execution 
time but you get a nice picture of how the execution is laid out in 
terms of time.

- Antti