Goroutine creation in FastCommit()

[SaveTheRbtz]

Issue To Be Solved

Currently, PersistentSlabStorage.FastCommit() does create adhoc goroutines, which may add a substantial overhead on servers with a high number of cores.

Suggested Solution

In the ideal world, each slab storage instance can have a goroutine pool of encoders ready to encode a set of keys. As a bonus, it would also be possible to reuse encoders, instead of creating a new one each time.

[fxamacker]

@SaveTheRbtz Thanks for opening this issue and also PR #268.

Suggested Solution In the ideal world, each slab storage instance can have a goroutine pool of encoders ready to encode a set of keys. As a bonus, it would also be possible to reuse encoders, instead of creating a new one each time.

I think each slab storage instance isn't reused for multiple transaction/script executions.

Unless I'm mistaken or things changed:

• Cadence runtime creates atree storage for each transaction/script execution.
• Cadence runtime calls atree storage to write cached deltas at the end of execution.
• FastCommit() only creates goroutines when there is cached deltas to be committed.

For these reasons, I don't think there's much impact or ROI to be gained by adding a pool to each slab storage instance.

Maybe we can evaluate adding a global worker pool of goroutines to atree.

Thoughts? @SaveTheRbtz @turbolent @ramtinms

[SaveTheRbtz]

Good point about slab storage lifetime (should've checked it before suggesting a solution). If cached deltas are common, then we should consider adding an injectable worker pool to atree. I'll take a look at the execution node profiles and come back here with more info.

[turbolent]

Good idea!

Yes, Faye's points describing the current usage of atree in Cadence are still correct.

But it might still make sense to have a worker pool here, either by defining it in atree for all users; or allowing it to be passed in by users, allowing it to be reused (better)