[Info-vax] Apache + mod_php performance

[Craig A. Berry]

On 9/25/24 4:17 PM, Arne Vajhøj wrote:
> On 9/25/2024 5:10 PM, Arne Vajhøj wrote:
>> Apache on VMS is prefork MPM. Yuck.
> 
> Which puzzles me.
> 
> VMS is a threading OS not a forking OS.

Preforking in Apache just means it creates subprocesses at start-up
time.  Whoever invented the term apparently thought fork() was the only
way to create a subprocess.  On VMS it will obviously use LIB$SPAWN or
SYS$CREPRC.

> And prefork MPM is really an early 90's traditional Unix design.
> 
> Using worker MPM on VMS would make more sense IMHO.

That requires everything running in each MPM process to be thread-safe.
It also probably doesn't provide the scaling advantages on VMS that it
would on unixen because there is no pthread_sigsetmask: all signals are
delivered in the main thread. Which means that somewhere around where
threads could provide a scaling advantage, the main thread will get
saturated and the advantage disappears. This based on the assumption
that signals would be used for things like asynchronous I/O completion;
I don't really know that for sure, but it seems like a pretty safe
assumption.

> The best would probably have been to create a VMS MPM
> based on the WinNT MPM.

And all of the Apache extensions would have to be rewritten to use QIOs
and ASTs?  That's a pretty big ask.