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 >> >
