I'm a beginner but I did install fpm to see how it works.
Did you set the fpm acces logs?
; The access log file
; Default: not set
access.log = "/usr/local/etc/php/8.0/log/www.access.log"
And the status page?
; The URI to view the FPM status page. If this value is not set, no URI
will be
; recognized as a status page. It shows the following information:
pm.status_path = /fpm-status
I don't know how ALB works, but does it make different requests/hit?
If not, that's maybe why FPM coughs
Cordially
Luis
On 20/12/2021 01:08, Dan Washusen wrote:
Also worth noting that Nginx OS does not experience the issues
(otherwise same setup)...
Dan
On Mon, Dec 20, 2021 at 10:58 AM Dan Washusen <d...@reactive.org> wrote:
Yeah, all those parameters are configured and everything works
fine when I switch to the MPM worker module. The 408 errors are
returned by Jetty and ProxyPass is configured to not reuse
connections (which seems to suggest not a KeepAlive issue), Jetty
is erroring because it receives no request data. Kind of seems
like the MPM event module is missing events/data (when behind the
ALB)...
Given that the TCP network load balancer doesn't show the issue,
maybe it's something to do with how the ALB sends the data to the
instance (e.g. Jumbo frames vs the standard MTU)...?
On Mon, Dec 20, 2021 at 10:37 AM Igor Cicimov <icici...@gmail.com>
wrote:
I will still say this is a timeout issue. Set the ALB timeout
to 3600 which is the max possible in case you do not know
where to start from. I guess you already have ALB logs enabled.
In apache check the KeepAliveTimeout, RequestReadTimeout and
ProxyTimeout and make sure they make sense for your user case.
Enable debug logs too for more details.
It is tough to guess without knowing your relevant
configuration but 408 is usually caused by client connection
being closed while keep-alive in use.
On Mon, Dec 20, 2021 at 10:12 AM Dan Washusen
<d...@reactive.org> wrote:
Thanks for the response. Timeouts are configured
appropriately...
To clarify; everything works fine through a TCP Network
Load Balancer pointing at the same infrastructure. There
is something about having a HTTP based Application Load
Balancer in front of an MPM event configuration that's
causing issues...
Dan
On Mon, Dec 20, 2021 at 10:01 AM Igor Cicimov
<icici...@gmail.com> wrote:
In a proxy chains like this getting the timeouts in
sync is the most important thing. Make sure that you
have done that.
On Mon, 20 Dec 2021, 08:37 Dan Washusen,
<d...@reactive.org> wrote:
Hi All,
I've been experimenting with the MPM event module
with Apache instances sitting behind an AWS
Application Load Balancer (ALB) and it really
doesn't seem to be working well. Response times
shoot up (compared to MPM event worker) and we see
a fair few 502 errors returned (by the AWS ALB.
The basic layout is: AWS Application Load Balancer
-> Apache 2.4.x -> AWS Internal TCP Load Balancer
(NLB) -> Jetty App Servers
Debugging the issue I think I traced it down to
Jetty returning a 408 error because it can't read
the request body in a timely manner. So it seems
like for some reason MPM is sending the request
body...?
We're running Ubuntu 20.04 with Apache
2.4.41-4ubuntu3.8 with the following worker
configuration:
|ServerLimit 250 StartServers 100 MinSpareThreads
75 MaxSpareThreads 250 ThreadLimit 64
ThreadsPerChild 64 MaxRequestWorkers 8000|
I've come across several random posts mentioning
that the MPM event module doesn't work behind an
ALB but no-one seems to be into any detail. Anyone
have some debugging/configuration suggestions?
Thanks,
Dan
p.s. I've created a serverfault post showing
graphs etc:
https://serverfault.com/questions/1087747/apache-2-4-mpm-event-module-causing-intermittent-502-errors-and-slow-response-ti
