[slack-digest] [2021-12-06] #general

[OpenWhisk Team Slack <ra...@apache.org>]

2021-12-06 21:02:33 UTC - Ben Carver: So, it looks like the OS on my Kubernetes node is killing my Java processes:
```$ dmesg | less | grep -i "out of memory"
[ 4552.610130] Memory cgroup out of memory: Kill process 186759 (java) score 2012 or sacrifice child
[10851.979067] Memory cgroup out of memory: Kill process 483710 (java) score 1998 or sacrifice child
[15302.580520] Memory cgroup out of memory: Kill process 204525 (java) score 2011 or sacrifice child
[16201.881584] Memory cgroup out of memory: Kill process 223867 (java) score 2000 or sacrifice child```
This explains why the OW actions would exit abruptly w/o any errors in their logs & also explains why I'd see OW spinning up new pods immediately after. I think I have configuration problem, but I can't find pertinent documentation.

There are several different locations where I can configure memory usage. I can set memory limits `whisk.limits.actions.memory`, I can specify the Invoker's memory `invoker.jvmHeapMB`, I can specify per-action memory limits via the `--memory` parameter, and I can specify a `memory` parameter for custom runtimes in the `stemCell` configuration (the `memory` parameter). Then there is `whisk.containerPool.userMemory`, which I am also confused about. (I have read the documentation about it, but it is still unclear to me how this parameter should be set.) I am not sure how exactly all of these fit together, but I think my issue is arrising from improperly configuring these values.

Should the invoker's `jvmHeapMB` be the largest of all of these, or does this not impact individual actions? How exactly does the `stemCell`'s `memory` parameter impact RAM available to individual actions? (e.g., if I set the `stemCell`'s `memory` parameter to 512MB and pass `--memory 1024MB` to an action using the custom runtime, then what happens?)
https://openwhisk-team.slack.com/archives/C3TPCAQG1/p1638824553170900
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