Analyze CachedBeaconState memory usage

[dapplion]

Motivation

To reduce memory footprint of Lodestar it's important to understand the trade-offs and requirements of the caches and the state.

Description

Commit comments after researching the caches and their implications for the state transition function. I believe they are useful to have a good context when taking decisions around them.

[codeclimate]

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[github-actions]

Performance Report

✔️ no performance regression detected

Full benchmark results

Benchmark suite	Current: 0a86840	Previous: 05e8265	Ratio
getCommitteeAssignments - req 1000 vs - 250000 vc	7.8871 ms/op	7.8467 ms/op	1.01
epoch altair - 250000 vs - 7PWei - processInactivityUpdates	2.1328 s/op	2.2111 s/op	0.96
epoch altair - 250000 vs - 7PWei - processRewardsAndPenalties	807.54 ms/op	883.38 ms/op	0.91
epoch altair - 250000 vs - 7PWei - processParticipationFlagUpdates	369.31 ms/op	353.07 ms/op	1.05
Process block - 250000 vs - 7PWei - with 0 validator exit	371.51 us/op	354.94 us/op	1.05
Process block - 250000 vs - 7PWei - with 1 validator exit	31.868 ms/op	32.650 ms/op	0.98
Process block - 250000 vs - 7PWei - with 16 validator exits	25.746 ms/op	26.815 ms/op	0.96
epoch phase0 - 250000 vs - 7PWei - beforeProcessEpoch	665.95 ms/op	634.02 ms/op	1.05
epoch phase0 - 250000 vs - 7PWei - processRewardsAndPenalties	467.87 ms/op	458.47 ms/op	1.02
epoch phase0 - 250000 vs - 7PWei - processEffectiveBalanceUpdates	123.28 ms/op	109.10 ms/op	1.13
getAttestationDeltas - 250000 vs - 7PWei	86.712 ms/op	92.590 ms/op	0.94
processSlots - 250000 vs - 7PWei - 32 empty slots	4.8881 s/op	4.5431 s/op	1.08
shuffle list - 16384 els	1.6833 ms/op	1.5060 ms/op	1.12
shuffle list - 250000 els	42.319 ms/op	21.502 ms/op	1.97
getPubkeys - persistent - req 1000 vs - 250000 vc	16.002 us/op	15.169 us/op	1.05
BLS verify - blst-native	1.6396 ms/op	1.6439 ms/op	1.00
BLS verifyMultipleSignatures 3 - blst-native	3.3682 ms/op	3.3547 ms/op	1.00
BLS verifyMultipleSignatures 8 - blst-native	7.2413 ms/op	7.2510 ms/op	1.00
BLS verifyMultipleSignatures 32 - blst-native	26.348 ms/op	28.700 ms/op	0.92
BLS aggregatePubkeys 32 - blst-native	39.928 us/op	35.819 us/op	1.11
BLS aggregatePubkeys 128 - blst-native	155.53 us/op	137.18 us/op	1.13
getAttestationsForBlock	87.175 ms/op	86.567 ms/op	1.01
validate gossip signedAggregateAndProof - struct	6.0880 ms/op	5.3061 ms/op	1.15
validate gossip signedAggregateAndProof - treeBacked	4.5816 ms/op	4.0418 ms/op	1.13
validate gossip attestation - struct	2.1204 ms/op	1.8708 ms/op	1.13
validate gossip attestation - treeBacked	2.1586 ms/op	1.9100 ms/op	1.13

by benchmarkbot/action