I am running ejabberd 17.04. I have about 900K+ users registered on my node. For me the system was running smoothly as I do not have more than 500 users online at any point. But recently, the users started to created groups and I can see the entry of these in mysql db MUC_room table. But as soon as these groups were created, my ejabberd performance went down drastically.
When I submit a message to ejabberd via my client, it takes anywhere from 15 seconds to 45 seconds for ejabberd to send back ACK for the message. Even stopping ejabberd node takes a considerable 10 minutes.
Any help in this regard will be highly appreciated.