Hello, I have performance issue when running my elixir app in kubernetes.
I have a function that do a query to cassandra and them decode the result. The average execution time of the query is around 2ms and 1ms for decode, but when I do several calls, I observe sometimes a spike in execution time reaching 70 to 90ms either on query or decode step (but never the two of them for a same call).
I guess it is not related to network since it happened on the decode step too.
The cassandra connection is using a pool, and the decode step is run after releasing the connection.
I tried reproducing the issue locally, but it never happened (either with a local cassandra or the one in my kubernetes cluster). I am starting to think that maybe the way my app is running on the kubernetes node might have an impact. I don’t really know what I should do to have a better understanding of what causing these spikes.
If anyone has ideas, it will help me a lot.
I am using elixir 1.10
The app is running on a 4vCPU - 3.6Gb memory
I tried with these flags, without success
+sbwt none +sbwtdcpu none +sbwtdio none