[Opt](scanner-scheduler) Opt scanner scheduler starvation issue. #41484
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…che#40641) When a scanner scheduler is stuck in executing a scan task, other scan tasks will starve and have no chance to execute, which will affect other queries. Currently, the scan task hopes to scan as much data as possible to reduce the overhead of scheduling switching. Currently, it hopes to obtain up to 10MB of data in `doris_scanner_row_bytes`. However, if a query scans a table with many rows of data, but the filtering rate is very high, the filter will eventually filter out a lot of data and will never get 10MB of data. It will keep getting and executing expression filtering, which will cause other scan tasks to starve. The current solution is to check `max_run_time_ms` by `MonotonicStopWatch`. After executing for a maximum of 1s, it will yield self's task for other tasks. When the scan task executes some time-consuming tasks, it needs to slice to do it.
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Thank you for your contribution to Apache Doris. Since 2024-03-18, the Document has been moved to doris-website. |
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run buildall |
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clang-tidy review says "All clean, LGTM! 👍" |
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TeamCity be ut coverage result: |
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Proposed changes
Backport #40641