This is using our official docker image which is built on top of ubuntu 16.04 LTS.
A user has reported this in https://github.com/testcontainers/testcontainers-java/issues/2802 and I've been able to reproduce this locally.
If you create 3-4 buckets, memcached cpu goes up to 100-150% inside the container. This happens with 6.5.0 and 6.5.1. I also tried with 6.0.3 and there the CPU is at 13%.
I triaged a bit with Dave Rigby and the current suspicion is that the sync durability monitor is consuming way more cpu in this setup than tuned for non-virtual linux hosts (less than 1%).. a couple % are probably fine, but this is keeping 1-2 cores busy all the time, even if there is no ops/traffic going through.
If you are not able to reproduce this I can provide the java program to run it, but all testcontainers-java does is spin up the docker container, configure it with alternate addr to expose the ports and then create 3 buckets.
Some more info from the initial triage:
points to the NonIO threads:
mpstat shows we're spending some time in sys: