perf(blockstore): Add LRU caches to blockstore operations used in consensus (backport #3003) #3081
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…sensus (#3003) Closes #2844 We are seeing that the blockstore loading operations get used in hot loops within gossip routines, and queryMaj23 routines. This PR reduces that overhead using an LRU cache. The LRU cache does have a mutex on every get, but the time with the LRU cache is 9x faster than without (before even adding in DB overheads), due to the proto unmarshalling saved. We could imagine a setup where we avoided a lock there entirely. I don't think this is worth right now, since the new code is 9x faster, and these mostly appear in catchup code which should not be highly contended for across peers at the same time. With the new benchmark I added: OLD: ``` BenchmarkRepeatedLoadSeenCommit-12 24447 54691 ns/op 46495 B/op 319 allocs/op ``` NEW: ``` BenchmarkRepeatedLoadSeenCommit-12 224131 6401 ns/op 8320 B/op 2 allocs/op ``` It turns out these gossip routines don't need mutative copies, so we could optimize out the large allocation in the future if we want. 1 hour cpu profile that shows this appearing in prod:  The state machine execution time here for context is 92 seconds. So this is adding up in system load (and GC! The GC load is 52GB, the entire trace is 200GB, with other parts being optimized down from recent PRs) --- #### PR checklist - [ ] Tests written/updated - [ ] Changelog entry added in `.changelog` (we use [unclog](https://github.com/informalsystems/unclog) to manage our changelog) - [ ] Updated relevant documentation (`docs/` or `spec/`) and code comments - [ ] Title follows the [Conventional Commits](https://www.conventionalcommits.org/en/v1.0.0/) spec --------- Co-authored-by: Daniel <daniel.cason@informal.systems> (cherry picked from commit 46e2484)
melekes
approved these changes
May 15, 2024
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Closes #2844
We are seeing that the blockstore loading operations get used in hot loops within gossip routines, and queryMaj23 routines. This PR reduces that overhead using an LRU cache.
The LRU cache does have a mutex on every get, but the time with the LRU cache is 9x faster than without (before even adding in DB overheads), due to the proto unmarshalling saved. We could imagine a setup where we avoided a lock there entirely. I don't think this is worth right now, since the new code is 9x faster, and these mostly appear in catchup code which should not be highly contended for across peers at the same time.
With the new benchmark I added:
OLD:
NEW:
It turns out these gossip routines don't need mutative copies, so we could optimize out the large allocation in the future if we want.
1 hour cpu profile that shows this appearing in prod:
The state machine execution time here for context is 92 seconds. So this is adding up in system load (and GC! The GC load is 52GB, the entire trace is 200GB, with other parts being optimized down from recent PRs)
PR checklist
.changelog(we use unclog to manage our changelog)docs/orspec/) and code commentsThis is an automatic backport of pull request #3003 done by [Mergify](https://mergify.com).