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perf: Parallelize saveNewNodes' DB writes with figuring out "what to write"

Open ValarDragon opened this issue 11 months ago • 4 comments

This PR parallelizes to SaveNodes, and figuring out what it is we have to write. ("saveNewNodes").

We can improve this in the future to process eveything but "Set" in another goroutine, and then keep a buffered queue for "Set" that completes asynchronously.

If this is not useful with the IAVL v2 work, can I just put this in the IAVL v1 line?

This PR as is feels like a pretty straightforward improvement, that should give a 7% sync improvement on Osmosis for IAVL v1 today. I don't think theres any tests to add here, I don't see any edge case here thats not covered by existing tests.

Benchmark for 2000 blocks on IAVL v1 on osmosis mainnet for context: image

This PR will drop the latency of this from 42 seconds to 24 seconds. However

We should be able to with subsequent work:

  • (No async commit) Parallelize latency for this function time to the longest of:
    • num nodes to hash * time to sha256 / num cores
    • DB writing all new nodes
  • And async commit removes the DB writing part

Better parallelism would make it:

  • No async commit be max(4 seconds, 18 seconds / num cores)
  • Async commit (18 seconds / num cores)

ValarDragon avatar Feb 25 '24 00:02 ValarDragon

Walkthrough

The update introduces a significant enhancement to the MutableTree structure, specifically within its saveNewNodes method. By leveraging goroutines, the process of saving nodes now occurs concurrently, leading to improved performance. This approach is complemented by the use of channels for effective communication and error management. Additionally, the update ensures that nodes are properly detached and their keys are recursively assigned, optimizing the process for parallel execution and enhancing overall efficiency and error handling.

Changes

File(s) Summary of Changes
mutable_tree.go Introduced goroutines in saveNewNodes for parallel node saving, with channels for communication and error handling. Optimized for parallelization, including recursive key assignment and improved efficiency.

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coderabbitai[bot] avatar Feb 25 '24 00:02 coderabbitai[bot]

Note that this code preserves functionality, as the recursive loop just builds a list of newNodes, and then we just one-by-one serially call SaveNode on it. So we still have the serial SaveNode behavior

ValarDragon avatar Feb 25 '24 01:02 ValarDragon

We've tested this gave a speedup on IAVL v1 on Osmosis!

ValarDragon avatar Feb 27 '24 16:02 ValarDragon

I love this conceptually, write nodes to disk as the tree is hashed and node keys are generated in parallel.

I guess one draw back is failing partway through tree traversal - those nodes are now possibly orphaned.

kocubinski avatar Feb 28 '24 18:02 kocubinski