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ancient pack: add low water mark #33785
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jeffwashington
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Codecov Report
@@ Coverage Diff @@
## master #33785 +/- ##
=======================================
Coverage 81.8% 81.8%
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Files 806 806
Lines 217428 217438 +10
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+ Hits 178056 178075 +19
+ Misses 39372 39363 -9 |
brooksprumo
reviewed
Oct 23, 2023
| @@ -182,15 +182,17 @@ impl AncientSlotInfos { | |||
| self.shrink_indexes.clear(); | |||
| let total_storages = self.all_infos.len(); | |||
| let mut cumulative_bytes = 0u64; | |||
| let low_threshold = max_storages * 50 / 100; | |||
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Is the current impl preferred over a divide by two?
Suggested change
| let low_threshold = max_storages * 50 / 100; | |
| let low_threshold = max_storages / 2; |
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Perhaps, introduce a const variable for this?
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I was thinking this is more tunable than /2. 80%, 20%, etc. Ultimately we might make this a tuning parameter? Even a cli argument? This choice seems sufficient for the moment based on mnb monitoring. And it beats the current 100 slots at a time impl.
brooksprumo
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Oct 23, 2023
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Problem
When we disable rewrites, we will accumulate old append vecs & slots. We use ancient append vec packing to combine those.
It is more efficient to pack a larger range of slots at a time instead of a small amount each call.
Summary of Changes
Add a low water mark. By default, when there are more than 10k ancient slots, the algorithm will pack down to 5k ancient slots. Then, the algorithm will do nothing until 10k is exceeded again.
Fixes #