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From André Warnier (tomcat) ...@ice-sa.com>
Subject Re: HTTP and MPM support
Date Sun, 27 Jan 2019 21:55:46 GMT
Hello William.
Thank you for commenting on this.

On 27.01.2019 21:13, William A Rowe Jr wrote:
> On Fri, Jan 25, 2019 at 11:35 AM John Dunlap <John@lariat.co <mailto:John@lariat.co>>
wrote:
>
>     I'm in the process of optimizing our web application for performance and one thing
>     that I was really excited to try was mod_http2 because it allows the browser to send
>     multiple requests through the same TCP connection with compressed headers. However,
>     when I enabled it and restarted apache I was greeted with this:
>
>     [Fri Jan 25 12:30:57.813355 2019] [http2:warn] [pid 10186] AH10034: The mpm module
>     (prefork.c) is not supported by mod_http2. The mpm determines how things are processed
>     in your server. HTTP/2 has more demands in this regard and the currently selected
mpm
>     will just not do. This is an advisory warning. Your server will continue to work,
but
>     the HTTP/2 protocol will be inactive.
>
>
> To this question, the answer should be blatantly obvious; http2 doesn't
> simply support multiple requests (connection: keepalive solved that)
> but supports parallel requests. This clearly isn't compatible with any
> single-threaded/single-worker per connection strategy.
>
> A hybrid mod_prefork could be coded to dispatch all worker requests
> across to distinct worker processes for a single connection, but I
> don't anticipate anyone interested in doing such development.
>
>     The last time I tried to use either mpm_worker or mpm_event my application was plagued
>     by seemingly random segfaults. Are there any plans to support other MPM's? If not,
the
>     benefits of HTTP2 appear to be permanently out of reach for our mod_perl applications
>     and that, honestly, might force us into seriously reevaluating our technology stack.
:(
>
>
> Your compatibility with the worker MPM is likely much stronger than
> with the event MPM; however... all request workers can behave in a
> "free threaded" manner under mod_http2, eliminating the relative
> simplicity of the worker MPM. Working out each and any of these
> specific segfaults occurs is the only way to improve the situation.
>
> For the general mod_perl activity to increase, the Apache Perl Project
> needs active volunteers and contributions. Consider this entire thread
> an open invitation to participate.
>

Invitation accepted, but
how can people who are not C programmers really contribute ?

I believe that there is a much wider user base for mod_perl, than may be evident from 
activity on the user list or on Bugzilla.

To quote Philippe Chiasson in 
http://www.apache.org/foundation/records/minutes/2018/board_minutes_2018_11_21.txt :

"It's not that the project is dead, in my opinion, more like dormant. It works,
it's being used by a large number of users, and is extremely stable."

Exactly. And therefore, there is very little noise about it.
mod_perl may be suffering from its general "it just works" aspect, and therefor be less 
attractive to developers (of mod_perl itself).

So let's imagine that there are currently worldwide a few hundreds/thousands users of 
mod_perl (by which I mean application developers who use mod_perl daily to 
develop/maintain important (to them) web-based applications), but of which only a tiny 
percentage is fluent in C (in which mod_perl is written). And among these people, there 
are quite a few which have a vested interest in the future of mod_perl (that's certainly 
my case, and my company's case), but who themselves don't feel qualified to be able to 
contribute to the code (also my case).
What could these mod_perl users do, to trigger renewed interest if the further development

of mod_perl, by people qualified to do so ?

Say for example that, collectively, we would be very interested in someone picking up and

resolving these problems that exist in running mod_perl with Apache MPM's other than prefork.
What would be the best way for us collectively to to try get the ball moving in that 
direction, and more than anything, avoid having mod_perl maybe being moved sooner or later

to the Apache Attic, for lack of /perceived/ interest ?

Genuinely curious and interested

André Warnier (soliplaya at apache.org)
(don't let the Tomcat committer label fool you; I'm a perl and mod_perl guy)



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