Are you using any sort of application performance monitoring (APM) product,
such as APM products from New Relic, DataDog, AppDyamics or Elastic?
What specifically are the 5xx errors you are getting?
As Jason mentioned less threads per process and more processes is always
generally better. Even if you don't use a full APM product, if you have a way
of collecting metrics, you could extract metrics data out of mod_wsgi using its
event callbacks. One of the things you can work out from that is
capacityutilisation. This will show whether you have way too many threads per
process, with potential for bottlenecking on one process due to uneven
distribution of requests across processes and GIL side effects if things are a
bit CPU bound.
Also, do you have:
WSGIRestrictEmbedded On
set so that you avoid starting Python interpreters in the main Apache child
processes.
If you only have the one Python WSGI application, you should also be setting:
WSGIApplicationGroup %{GLOBAL}
Graham
> On 18 Feb 2020, at 12:55 pm, Andrew Charles <[email protected]> wrote:
>
> Ubuntu 18.04.04
> Apache 2.4.29 (event)
> mod_wsgi 4.5.17
> Python 3.6.8
> Django 2.2.10
>
> WSGIScriptAlias / ...wsgi.py
> WSGIDaemonProcess name processes=8 threads=30 queue-timeout=45
> socket-timeout=60 request-timeout=60 inactivity-timeout=0 startup-timeout=45
> deadlock-timeout=60 graceful-timeout=15 eviction-timeout=0
> python-path=...base/ python-home=...virtualenv/
> WSGIProcessGroup name
>
>
> AWS ec2 c5.xlarge 4 CPUs 8GB Mem (ASG autoscaling between 4 and 10 instances)
> behind an ELB
> Averaging 100,000,000 requests per day (107 mil today)
>
> We have a few django api endpoints that are very simple, which only hit a
> local or separate redis cache, no db hits. We relay data to firehose but use
> django-q to offload those tasks. Requests take around 200ms but a fair number
> are 400-500ms. The ELB reports the average as 60ms. Each instances uses
> between 4-5GB mem. I've been trying to get more performance out of our
> instances and reduce our 5XXs. I previously tried 3 processes and the default
> (15) threads. I've been researching the best ways to change settings but it
> seems like it's unique to every setup and there's no easy rules to follow.
> I'm looking for suggestions or at least someone to tell me I'm on the right
> track.
>
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