apache / apache/uniffle

[Bug] Long tail tasks in the Write Stage retry phase results in data loss.

Open
#2,300 2 comments 0 reactions 0 assignees View on GitHub
Dominant language
Java
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Forks
172
Avg merge
5d 17h
Merged PRs (30d)
5

Description

### Code of Conduct

- [X] I agree to follow this project's [Code of Conduct](https://www.apache.org/foundation/policies/conduct)

### Search before asking

- [X] I have searched in the [issues](https://github.com/apache/incubator-uniffle/issues?q=is%3Aissue) and found no similar issues.

### Describe the bug

During the Write Stage retry phase, the MapOutputTrackerMaster clears the MapStatus corresponding to the shuffleId on the Driver side. However, when a large number of partitions are encountered, the MapStatus may not be completely cleared. Retry at the Stage, the task becomes less, resulting in data loss. At present, I encountered a 40000 Partition, resulting in data loss.
Below is a screenshot of my problem:
![image](https://github.com/user-attachments/assets/433e9712-5b3c-448b-a21c-c6aabfb79e8b)

### Affects Version(s)

0.10.0

### Uniffle Server Log Output

_No response_

### Uniffle Engine Log Output

_No response_

### Uniffle Server Configurations

_No response_

### Uniffle Engine Configurations

_No response_

### Additional context

_No response_

### Are you willing to submit PR?

- [X] Yes I am willing to submit a PR!

Contributor guide

Open the contributing guide

Research direction

Start at MapOutputTrackerMaster and trace how MapStatus is cleared during the Write Stage retry phase, especially with a shuffle containing 40,000 partitions. Reproduce the retry with a large partition count and verify that all required MapStatus data remains available and that the retried stage completes without data loss.

Written by the indexing model from the issue text.

Assessment

Tech stack
java, spark
Domain
distributed-systems
Issue type
Bug
Difficulty
4/5
Estimated time
3-5 days
Activity status
Stale
Clarity
Needs clarification
Newbie friendliness
35/100

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