Redis Server has been killed a few times this week by the OOM. More info in this post on stackoverflow.

After setting the maxmemory limit to 3GB, and maxmemory-policy to allkeys-lru, things should have gotten better. For some reason node.js workers would die as soon as they were restarted, reporting that they couldn’t connect to Redis.

Starting the process manually would connect successfully, so the problem seemed to be with pm2, which manages the node cluster.

Fix

I tried killing pm2 by running the following command.

$ pm2 kill

Then, I restarted the node cluster, and everything was back to normal.

$ sudo service io-server-cluster restart