We have set up some environments using Couchbase 4.0.0-4051 Community Edition (build-4051) on AWS Linux. From what we observe, it uses CPU constantly even though there is a minimal load.
In one environment, we have 2 Couchbase nodes running on m3.large (2 vCPU, 7.5GB RAM) using one replication. There is only one bucket being used with 6.3M items in it. All the data was migrated, and after the migration, there is little to no writes to the data, with only a few occasional reads.
Since the time of the migration (which is a week ago), both servers are showing up as 80% CPU usage constantly in AWS Monitoring. When I checked using top command in the node, it shows that indexer process is the one using CPU most of the time. The Index settings are set to only use 2 Indexer Threads, and Indexer RAM Quota is set to 512MB.
Actually, this is not the only environment that we find Couchbase constantly using CPU. Some other environments have much smaller bucket size, with very few usage, but the CPU is constantly being used 15-30% all the time. When I restarted the nodes, it normally goes away, but comes back whenever there are some operations done, and then stays at that CPU range forever.
May I know if this is a known issue with Couchbase 4.0 Community Edition? Or something possibly wrong with the setup of the Couchbase servers?