Potential performance issue in initiateValidatorExit()

[dapplion]

Describe the bug

Every time initiateValidatorExit() is called it iterates over the entire validators array. initiateValidatorExit may be called multiple times per block with the right conditions.

lodestar/packages/beacon-state-transition/src/util/validatorStatus.ts

Line 37 in e481a84

const exitQueueChurn = Array.from(state.validators).filter((v: phase0.Validator) => v.exitEpoch === exitQueueEpoch)

Expected behavior

We should do something smarter and cache this computation

[twoeths]

there is a performance test for it

lodestar/packages/beacon-state-transition/test/perf/phase0/fast/block/block.test.ts

Line 32 in 393836d

it("should process multiple validator exits in same block", async () => {

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed in 15 days if no further activity occurs. Thank you for your contributions.

[dapplion]

@tuyennhv do we have a performance problem? Processing a block with 16 exits is a x100 times slower..

Process regular block                                                  172.8628 ops/s      5.784933 ms/op   2581 runs
Process blocks with 16 validator exits                                 1.727984 ops/s      578.7092 ms/op    512 runs

[twoeths]

@tuyennhv do we have a performance problem? Processing a block with 16 exits is a x100 times slower..

Process regular block                                                  172.8628 ops/s      5.784933 ms/op   2581 runs
Process blocks with 16 validator exits                                 1.727984 ops/s      578.7092 ms/op    512 runs

yeah we should definitely improve it