Re: Apache + mod_php performance

On 9/30/2024 9:25 PM, Arne Vajhøj wrote:

On 9/30/2024 9:10 PM, Dave Froble wrote:

On 9/30/2024 8:33 PM, Arne Vajhøj wrote:

On 9/30/2024 8:24 PM, Lawrence D'Oliveiro wrote:

On Mon, 30 Sep 2024 19:50:38 -0400, Arne Vajhøj wrote:

On 9/29/2024 11:15 PM, Lawrence D'Oliveiro wrote:

On Sun, 29 Sep 2024 22:34:04 -0400, Arne Vajhøj wrote:

But I am pretty sure that it will not work on VMS.

>
That’s what I figured. VMS, like Windows, really wants you to use
threads.

>
For massive parallel processing on VMS then threads not
processes is the way to go.

>
Threads require shared memory, though. Processes allow you to have a mix
of shared and private data, plus the use of IPC mechanisms like message
passing. This makes for a looser coupling, which better suits the way
massively parallel systems are built.

>
It is undeniable that multiple processes are more loosely coupled
than multiple threads.
>
But efficiency is a problem. VMS does not do fork. Process creation
is expensive on VMS. None of that fancy moving descriptors over
Unix socket stuff.
>
VMS got plenty of methods for IPC. A solution with a fixed number
of processes doing IPC between each other may work fine.
>
But the concept of constantly starting new processes and killing
old processes is not going to perform great.

>

Well, now, that is a rather bold statement.

>
Sometimes I make such.
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:-)
>

Granted, starting up a new process involves some overhead.
>
But it really depends upon the requirements.  The more use out of a process
once it is started, the better overall performance.  If a group of worker
processes is started once, then used for many tasks, then that overhead
happens only once.  Perhaps once a day, week, month, and even year.  There are
various communication methods available on VMS.
>
In the end, it comes down to the requirements.  An engineer must evaluate the
task(s) and determine what methods will give adequate results.

>
There are obviously a scale.
>
But the Apache case is to start with 5 processes, start 145 new
processes in a few seconds and then kill 140 again after maybe
30-45 seconds. And repeat.
>
Arne
>
>
>

Perhaps the real problem is using a poorly designed application, regardless of how popular it might be?
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