Fix panic as a result of duplicate write request cleanup #7176
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56quarters
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Jan 19, 2024
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Should this have a CHANGELOG entry? It's a niche bug but seems worth mentioning. |
This was referenced Apr 1, 2024
colega
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We follow a simple logic: if we don't call next(), we should call pushReq.Cleanup(). However, there's nothing in the code ensuring that, which leads to bugs and fixes like: - #7176 - #7755 A simple way to prevent that is to couple the `cleanupInDefer = false` to the `next()` call, and this does exactly that. Note that `nextOrCleanup` is introduced just for convenience, and it's inlined. Signed-off-by: Oleg Zaytsev <mail@olegzaytsev.com>
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colega
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Apr 1, 2024
We follow a simple logic: if we don't call next(), we should call pushReq.Cleanup(). However, there's nothing in the code ensuring that, which leads to bugs and fixes like: - #7176 - #7755 A simple way to prevent that is to couple the `cleanupInDefer = false` to the `next()` call, and this does exactly that. Note that `nextOrCleanup` is introduced just for convenience, and it's inlined. Signed-off-by: Oleg Zaytsev <mail@olegzaytsev.com>
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What this PR does
This PR fixes a possible panic introduced by #6970. In
prePushRelabelMiddleware, whenMetricRelabelingEnabledreturns true, it would call to thenextmiddleware in the chain, then callCleanUpin a defer. This results inCleanUpbeing called twice. Two conditions result:The existing middleware test was attempting to find this condition via the
cleanupCallCountfield, but unfortunately the test is too simple to reproduce the behavior of actual distributor middleware in a running Mimir cluster. To reproduce the issue in test, we can insert a fake cleanup function after callingCleanUp, so that if it is called again we will catch it and fail the test.I've reproduced this issue in a local mimir cluster via helm and verified that the proposed fix works.
Which issue(s) this PR fixes or relates to
Checklist
CHANGELOG.mdupdated - the order of entries should be[CHANGE],[FEATURE],[ENHANCEMENT],[BUGFIX].about-versioning.mdupdated with experimental features.