pageserver: fixes for layer visibility metric #8603
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2112 tests run: 2043 passed, 0 failed, 69 skipped (full report)Code coverage* (full report)
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1e944bc at 2024-08-06T13:37:27.624Z :recycle: |
jcsp
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Aug 12, 2024
## Problem In staging, we could see that occasionally tenants were wrapping their pageserver_visible_physical_size metric past zero to 2^64. This is harmless right now, but will matter more later when we start using visible size in things like the /utilization endpoint. ## Summary of changes - Add debug asserts that detect this case. `test_gc_of_remote_layers` works as a reproducer for this issue once the asserts are added. - Tighten up the interface around access_stats so that only Layer can mutate it. - In Layer, wrap calls to `record_access` in code that will update the visible size statistic if the access implicitly marks the layer visible (this was what caused the bug) - In LayerManager::rewrite_layers, use the proper set_visibility layer function instead of directly using access_stats (this is an additional path where metrics could go bad.) - Removed unused instances of LayerAccessStats in DeltaLayer and ImageLayer which I noticed while reviewing the code paths that call record_access.
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Problem
In staging, we could see that occasionally tenants were wrapping their pageserver_visible_physical_size metric past zero to 2^64.
This is harmless right now, but will matter more later when we start using visible size in things like the /utilization endpoint.
Summary of changes
test_gc_of_remote_layersworks as a reproducer for this issue once the asserts are added.record_accessin code that will update the visible size statistic if the access implicitly marks the layer visible (this was what caused the bug)Checklist before requesting a review
Checklist before merging