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perf(blockstore): Add LRU caches to blockstore operations used in con… #76

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merged 2 commits into from
May 25, 2024

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…sensus (backport cometbft#3003) (cometbft#3083)

Closes cometbft#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:

image

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 to manage our changelog)
  • Updated relevant documentation (docs/ or spec/) and code comments

mergify bot and others added 2 commits May 25, 2024 11:48
…sensus (backport cometbft#3003) (cometbft#3083)

Closes cometbft#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:

![image](https://github.com/cometbft/cometbft/assets/6440154/5a7e0f02-8385-4c01-aa6a-dba2a2bf376d)

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)

---

- [ ] 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
<hr>This is an automatic backport of pull request cometbft#3003 done by
[Mergify](https://mergify.com).

---------

Co-authored-by: Dev Ojha <[email protected]>
Co-authored-by: Anton Kaliaev <[email protected]>
@ValarDragon ValarDragon merged commit a9d1091 into osmo/v0.37.4 May 25, 2024
17 of 18 checks passed
@PaddyMc PaddyMc added the S:backport/v25 backport to the osmo-v25/v0.37.4 branch label May 28, 2024
PaddyMc added a commit that referenced this pull request May 28, 2024
…… (backport #76) (#81)

* perf(blockstore): Add LRU caches to blockstore operations used in consensus (backport cometbft#3003) (cometbft#3083)

Closes cometbft#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:

![image](https://github.com/cometbft/cometbft/assets/6440154/5a7e0f02-8385-4c01-aa6a-dba2a2bf376d)

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)

---

- [ ] 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
<hr>This is an automatic backport of pull request cometbft#3003 done by
[Mergify](https://mergify.com).

---------

Co-authored-by: Dev Ojha <[email protected]>
Co-authored-by: Anton Kaliaev <[email protected]>
(cherry picked from commit 0c10bd5)

* Add Changelog

(cherry picked from commit 4594f29)

# Conflicts:
#	CHANGELOG.md

---------

Co-authored-by: mergify[bot] <37929162+mergify[bot]@users.noreply.github.com>
Co-authored-by: Dev Ojha <[email protected]>
Co-authored-by: PaddyMc <[email protected]>
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