helm: derive memcached's -m flag from resources overrides to prevent OOM kills - #16348
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bharathjyothi wants to merge 3 commits into
Open
helm: derive memcached's -m flag from resources overrides to prevent OOM kills#16348bharathjyothi wants to merge 3 commits into
bharathjyothi wants to merge 3 commits into
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…t exceed the container's memory limit (grafana#9737)
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What this PR does
Every memcached-backed cache (
chunks-cache,index-cache,metadata-cache,results-cache) alwayspassed
.allocatedMemoryto memcached's own-mflag, even when a user overrode.resourceswith alower memory limit. That mismatch let memcached grow past the container's real memory limit and get OOM
killed.
This PR derives
-mfromresources.limits.memory(falling back toresources.requests.memory) when.resourcesis overridden, using the existingmimir.siToByteshelper and the same 1.2x headroom ratiothe default path already uses. Behavior is unchanged when
.resourcesisn't overridden.Verified with
helm templateagainst everyci//ci/offlinefixture (no diffs) plus a new regressionfixture, and end-to-end on a real cluster below.
Before/after on a live cluster (100Mi memory limit, 300MB write load)
Before:
-m 8192→ podOOMKilled(exit 137) after ~95MB written.After:
-m 83→ all 300MB written, 0 restarts, memcached self-manages via LRU eviction(
limit_maxbytes: 87031808= 83MiB exactly,evictions: 218).Which issue(s) this PR fixes or relates to
Fixes #9737
Checklist
CHANGELOG.mdupdated - the order of entries should be[CHANGE],[FEATURE],[ENHANCEMENT],[BUGFIX]. If changelog entry is not needed, please add thechangelog-not-neededlabel to the PR.about-versioning.mdupdated with experimental features.