Ever since I tuned my database server to accept high concurrent users (using mysql tuner), I am unable to install plugins or upgrade moodle. I always get stuck on the Plugin Check page where you have to click on "Upgrade Moodle Database Now". It usually takes an unusually long time and then shows 502 Gateway error. Trying to purge all caches too takes a long time and then shows the 502 page. I am not sure if Database is the problem here.
MySQL error log:
2020-11-11 0:29:13 23881467 [Warning] Aborted connection 23881467 to db: 'moodle' user: 'moodle
user' host: '184.108.40.206' (Got an error reading communication packets)
[11-Nov-2020 00:29:13] WARNING: [pool www] child 903 exited on signal 9 (SIGKILL) after 4897.868
787 seconds from start
Nginx error log:
2020/11/11 00:29:13 [error] 857#857: *11843 recv() failed (104: Connection reset by peer) while
reading response header from upstream, client: 10.0.0.5, server: sathyabama.cognibot.in, request
: "GET /admin/index.php?cache=0&confirmrelease=1&confirmplugincheck=1 HTTP/2.0", upstream: "fast
cgi://127.0.0.1:9000", host: "sathyabama.cognibot.in", referrer: "https://sathyabama.cognibot.in
The webserver, database, redis and filestore are each in seperate servers. They all run Debian and Moodle 3.9.1.
Please let me know how to go about solving this and if you need any additional information. Thanks!