Optimize indexMaxBlobs for lower memory usage#2631
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MichaelEischer wants to merge 1 commit intorestic:masterfrom
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Optimize indexMaxBlobs for lower memory usage#2631MichaelEischer wants to merge 1 commit intorestic:masterfrom
MichaelEischer wants to merge 1 commit intorestic:masterfrom
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Each index file is currently loaded into a separate hashmap. Go hashmaps use a load factor of 6.5/8 and allocate an array whose size is a power of two. For 2000 entries this requires a array with 4096 slots which wastes a lot of memory. The maximum number of entries for that array size would be 3328. However, leave some headroom as the index_uploader only runs every 30 seconds.
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Obsoleted by #2749. |
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What is the purpose of this change? What does it change?
Reduce the memory required to load preliminary index files. If an preliminary index is uploaded during backup and it is considered as full because its blob count reached indexMaxBlobs, then the hashmap used to loaded this index wastes a lot of memory:
Go hashmaps use a load factor of 6.5/8 and allocate an array whose size is a power of two. For 2000 entries this requires a array with 4096 slots which wastes a lot of memory. The maximum number of entries for that array size would be 3328. However, leave some headroom as the index_uploader only runs every 30 seconds.
I'm not sure whether a changelog entry is required. The memory usage of restic should be slightly lower when running backups without calling rebuild-index inbetween, but it's hard to tell by how much.
Was the change discussed in an issue or in the forum before?
No. I noticed the problem during the discussions in #2523.
Checklist
[ ] I have added tests for all changes in this PR[ ] I have added documentation for the changes (in the manual)changelog/unreleased/that describes the changes for our users (template here)gofmton the code in all commits