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From Gabriel Ambuehl <>
Subject Re[2]: perchild on FreeBSD 5?
Date Thu, 15 Aug 2002 10:13:44 GMT
Hi Rasmus Lerdorf,
you wrote.

>> time spent in mutex-protected code is 99% of the total request processing
>> time, then the server will scale poorly.  The key success factor is to not
>> use libraries that require locking for lengthy operations.
RL> If, for example, we have to mutex an entire database library and every

So it is expected to break up, for example, PHP in libraries that do
support threading explicitely and such that don't or aren't known to
do it instead of having a mutex around all of PHP?

I'm aware of the fact that request for static content will still
get served and that's very nice since many sites consist of few dynamic
pages and loads of images ;-) so in the end, the scalability might not
suffer too much in our case as we only host low traffic sites on
shared servers anyway and on the dedicated ones, prefork has proven to
offer quite acceptable performance.

In view of this "It's impossible to tell which libs are thread safe"
wouldn't it perhaps make sense to have a perchild version that uses
processed instead of threads? I sure know that this would result in a
insane amount of sleeping processes in a massive Virtualhosting setup
but in my tests a very low end 500Mhz FreeBSD 4.6 box with 256MB RAM had
no problem whatsoever with 2000 sleeping Apache processes belonging to 250
DISTINCT instances of 1.3.26, all based upon different config files
and running on different ports . Swap wasn't used and in idle state,
the 2000 processes consumed less than 1.5% CPU...


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