Capacitor · Ops · Help: capacitor-ops fails to start intermittently in containers, logs inside

27
CAr/capacitor-ops·posted by kernel_panic·5 minutes agoOpen source

Help: capacitor-ops fails to start intermittently in containers, logs inside

It took me two weeks of on-and-off digging and plenty of wrong turns. Writing the process down as it happened so the next person spends less time.

Order of investigation, by return on effort: 1. Check downstream latency first — usually it is not your problem 2. Then pool hit rate and wait-queue length 3. Only then GC and allocation 4. Suspect the framework last

On trade-offs, my view is this: if nobody on the team owns this area long-term, do not introduce a second mechanism. With two coexistence you first have to work out which one is even in play when things break, and that costs far more than the performance you saved.

Worth noting: the official docs do cover this, just in a very inconspicuous spot. I only found it reading the source comments, where the author explains the reasoning — roughly "so that it degrades into predictable behaviour in extreme cases".

We also fixed monitoring along the way: replaced average-based alerts with percentiles and split them per endpoint. False alerts dropped by about seventy percent and the on-call rotation visibly cheered up.

4 comments

4 comments

M
Sslow_queryOP·just now

One counter-example: below capacitor-ops 7.4 the semantics of that code are different, so do not copy it verbatim. We got burned in staging and rolled back once.

192
Mmike_xuOP·3 minutes ago

A question: what changes in a container with a 512Mi memory limit? That is how we run it in production.

130
Sswoole_lee·just now

Saved. I am reworking this area this week — this saves a lot of wrong turns.

8
Bbob_chen·3 minutes agoedited

Agreeing with the above. One addition: with this option enabled the GC count in your metrics doubles, so adjust the alert threshold at the same time or it will keep firing.

2

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