hai-tao-1 opened a new pull request, #36597:
URL: https://github.com/apache/spark/pull/36597
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### What changes were proposed in this pull request?
- Add a spark property, spark.history.fs.update.batchSize(default 1000),
which specifies the batch size for updating new eventlog files.
- For each eventlog scan/parse process, only a max of
`spark.history.fs.update.batchSize` jobs are scanned/parsed. This allows the
scan process ends within a reasonable time, so new eventlog files(appeared
after the scan process starts) can be scanned sooner.
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### Why are the changes needed?
Current Spark History Server suffers when there are a large number of
eventlog files under eventLog.dir: when a SHS starts, the initial scan may take
a long time, and new eventlog files would not be scanned/parsed until the
initial scan completes.
For example, if the initial scan takes 1-2 days(this is not uncommon in
large environments), the newly finished spark jobs would not show up in SHS
since their eventlog files are not scanned/parsed until the initial scan
process finishes. This would result in a 1-2 days SHS malfunctioning since the
newly finished spark jobs are most likely to be queried by users.
This PR adds a limit for each scan process to
`spark.history.fs.update.batchSize`, so that each scan can finish within a
reasonable time(default 1000 jobs can usually be scanned in ~10-15 mins but
this can vary depending on the sizes of the eventlog files). This will prevent
the long initial scan process from blocking the newly appeared eventlog files
be scanned.
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### Does this PR introduce _any_ user-facing change?
No.
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### How was this patch tested?
Tested locally:
- Tested with unit tests in the core module and all passed.
- Placed 10 eventlog files under `eventLog.dir`, and set
`spark.history.fs.update.batchSize` to 2. When the SHS started, observed that
the scan process parsed 2 files at each time(starting from the files with the
latest modification time).
- Added a new eventlog file after the first scan started, and observed that
the 2nd scan process picked up and parsed the new eventlog file before parsing
other remaining (older) eventlog files.
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