Get rid of `ProcessList` for mpp query
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- Dominant language
- C++
- Stars
- 1k
- Forks
- 423
- Avg merge
- 1d 15h
- Merged PRs (30d)
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Description
Enhancement
ProcessList is inherited from Clickhouse, and mainly used for query lifetime management and holding the query's memory tracker, for MPP query, we already have MPPTaskManager to manage the lifetime of MPPTask, and MPPTask itself holds the task's memory tracker, so we can remove ProcessList related logic for MPP queries.
In exceptional cases, the ProcessList may be blocked, causing all mpp queries to be stuck. related #6418
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First steps
- Read the whole issue, then the project's contributing guide.
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- Fork the repository and make your change on a branch.
- Open a pull request that references the issue number.
Research direction
Start by tracing ProcessList-related logic used by MPP queries and compare it with MPPTaskManager and MPPTask lifetime and memory-tracking responsibilities. Done means MPP queries no longer depend on ProcessList, including in exceptional cases where ProcessList can block, while existing query behavior remains covered by the repository's tests.
Written by the indexing model from the issue text.
Assessment
- Tech stack
- cpp
- Domain
- backend, databases, distributed-systems
- Issue type
- Refactor
- Difficulty
- 4/5
- Estimated time
- 3-5 days
- Activity status
- Stale
- Clarity
- Mostly clear
- Newbie friendliness
- 35/100