Increase compute_shuffled_index cache from 96 to 65536 entries#5046
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jtraglia merged 1 commit intoethereum:masterfrom Mar 26, 2026
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The existing LRU cache for `compute_shuffled_index` was sized at `SLOTS_PER_EPOCH * 3` (96 entries), which is smaller than the default mainnet test validator set (256 validators). This caused cache thrashing on mainnet preset tests. Increasing to `2**16` (65536) entries allows the cache to hold the full shuffle permutation for the test validator set, resulting in a 51% speedup for some Gloas tests. Memory overhead scales with actual usage, not cache capacity, so the larger size has should come at little cost for small validator sets.
jtraglia
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Mar 27, 2026
In #5046, we increased the cache size from 96 to 65,536. I believe this was too much as our runners are "losing contact" (aka crashing) around 8 hours into the mainnet-gloas tests. I suspect they are running out of memory; that's the common reason. In my testing, 1024 will improve performance in most situations except the large validator set tests.
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The existing LRU cache for
compute_shuffled_indexwas sized atSLOTS_PER_EPOCH * 3(96 entries), which is smaller than the default mainnet test validator set (256 validators). This caused cache thrashing on mainnet preset tests.Increasing to
2**16(65536) entries allows the cache to hold the full shuffle permutation for the test validator set, resulting in a 51% speedup for some Gloas tests. Memory overhead scales with actual usage, not cache capacity, so the larger size has should come at little cost for small validator sets.