Re: Apache + mod_php performance

On 9/26/2024 10:44 AM, Craig A. Berry wrote:

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.

Yes. But they behave different from fork.

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.

Well - the threaded PHP engine that does run on VMS (Tomcat + Quercus)
performs much better, so I am optimistic. I am pretty sure that the
Java RT use standard socket IO and pthreads, so it must be possible
to achieve the same numbers in C.

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.

Why would extensions require being rewritten to use QIO's and
AST's?
Thread safe IO does not require those.
And most extensions are already available in a thread safe
version. Obviously no guarantee that it will build unchanged
on VMS, but ...
Arne