apache / apache/datafusion

Lock free MPSC channel for RepartitionExec

Open
#6,928 0 comments 0 reactions 0 assignees View on GitHub
enhancement
Dominant language
Rust
Stars
9.3k
Forks
2.4k
Avg merge
3d 7h
Merged PRs (30d)
344

Description

### Is your feature request related to a problem or challenge?

Currently, `RepartitionExec` is implemented with a custom MPSC, based on the parking_lot. However, this implementation has poor performance and may become a bottleneck in some queries, when the number of input/out partitions is large.

### Describe the solution you'd like

We could use a lock-free MPSC, like `flume`, to improve the performance.

### Describe alternatives you've considered

_No response_

### Additional context

I have implemented my idea, and the benchmark on tpch shows it could accelerate the query:

Comparing main and feature_flume
--------------------
Benchmark tpch.json
--------------------

| Query | main | feature_flume | Change |
| ----------- | ---------- | ------------ | ------------- |
| QQuery 1 | 317.52ms | 317.86ms | no change |
| QQuery 2 | 73.18ms | 70.41ms | no change |
| QQuery 3 | 136.38ms | 113.01ms | +1.21x faster |
|QQuery 4 | 84.27ms | 51.30ms | +1.64x faster |
| QQuery 5 | 170.56ms | 123.28ms | +1.38x faster |
| QQuery 6 | 83.52ms | 81.93ms | no change |
| QQuery 7 | 249.60ms | 220.84ms | +1.13x faster |
| QQuery 8 | 191.66ms | 175.73ms | +1.09x faster |
| QQuery 9 | 282.38ms | 213.37ms | +1.32x faster |
| QQuery 10 | 230.92ms | 153.20ms | +1.51x faster |
| QQuery 11 | 52.68ms | 54.10ms | no change |
| QQuery 12 | 153.50ms | 119.72ms | +1.28x faster |
| QQuery 13 | 314.86ms | 313.01ms | no change |
| QQuery 14 | 115.02ms | 115.82ms | no change |
| QQuery 15 | 90.32ms | 89.26ms | no change |
| QQuery 16 | 67.44ms | 61.57ms | +1.10x faster |
| QQuery 17 | 785.40ms | 786.18ms | no change |
| QQuery 18 | 636.27ms | 491.24ms | +1.30x faster |
| QQuery 19 | 232.26ms | 231.82ms | no change |
| QQuery 20 | 261.95ms | 240.57ms | +1.09x faster |
| QQuery 21 | 351.81ms | 239.96ms | +1.47x faster |
| QQuery 22 | 54.88ms | 49.39ms | +1.11x faster |

Contributor guide

Open the contributing guide

Research direction

Start with the RepartitionExec implementation and its custom parking_lot-based MPSC, then compare the proposed flume channel behavior and API requirements. Use the provided tpch benchmark comparison to evaluate performance across queries, and consider the work done when the channel replacement is correct and the benchmark results support the change.

Written by the indexing model from the issue text.

Assessment

Tech stack
rust
Domain
backend, performance
Issue type
Feature
Difficulty
4/5
Estimated time
3-5 days
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
35/100

Get new issues in your inbox

A short digest of beginner-friendly GitHub issues.