uwsgi: detect and empty full queue

Question

I have a python app behind supervisor and uwsgi.

At a certain point, my app stopped to answer the queries with this message in the logs:

Tue Sep  6 11:06:53 2022 - *** uWSGI listen queue of socket "127.0.0.1:8200" (fd: 3) full !!! (101/100) ***

In my use case,

If a query is not answered within 1s, the answer does not matter anymore; the client app will automatically re-do the request
restarting the whole uwsgi takes around half an hour

Thus I prefer to lose few requests than restarting.

QUESTIONS :

Is it possible to detect a full queue from inside the python app ?
Is it possible to clear the queue from inside ?

Precision: this question is not about fixing the underlying issue. I'm working on that separately. It is only about knowing if this particular workaround is possible and how to implement it.

I'm using uwsgi 2.0.20. Looking at the queue framework does not help since uwsgi has no attribute (e.g.) queue_slot. Doc outdated ?

EDIT I can reproduce the error with this simple bash script:

#!/bin/bash
 
for i in {0..200}
do
  echo "Number: $i"
  sleep 0.2
 curl -X POST "http://localhost:1103/my_app" &
done

(my app accepts POST, not GET)

uwsgi: detect and empty full queue

0 Answers