AHeise opened a new pull request #16990:
URL: https://github.com/apache/flink/pull/16990
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## What is the purpose of the change
There is a performance regression of 15% on new sources in InputBenchmark.
## Brief change log
A couple of issues are fixed with this commit:
- MetricTrackingOutput in SourceOperator adds 1 virtual calls per record.
This accounts for ~5% of the regression. The solution is to move the
functionality inside SourceOutput. The newly added SourceListener abstracts
from the InternalSourceReaderMetricGroup and can be used inside the
SourceOutput right before record/watermark emission.
- Lazy registration of CURRENT_EMIT_EVENT_TIME_LAG gauge. This adds ~2%
overhead as it checks for each record whether the metric has been registered
already. The solution is to always add the metric and just return some
UNDEFINED value when there is no record.
- Check of NO_TIMESTAMP. This adds ~3% overhead as it's a long comparison
for each record. The solution is to lazily check the timestamp in the gauge.
This solution depends on the prior solution.
- Fusion of recordEmitted() and eventTimeEmitted(). This removes 2% overhead
and is possible after the previous optimizations.
A bit of regression may remain after this commit. Future work may further
improve the situation. However, it may also be the price to be paid for the
additional metrics. In real sources with I/O, the remaining regression will not
be as noticeable. For example, the micro benchmarks imply that the new source
is 2x faster than the old sources but we do not see any difference in actual
sources.
## Verifying this change
Functionality covered by test. Performance tested with benchmark-requested.
## Does this pull request potentially affect one of the following parts:
- Dependencies (does it add or upgrade a dependency): (yes / **no**)
- The public API, i.e., is any changed class annotated with
`@Public(Evolving)`: (yes / **no**)
- The serializers: (yes / **no** / don't know)
- The runtime per-record code paths (performance sensitive): (**yes** / no
/ don't know)
- Anything that affects deployment or recovery: JobManager (and its
components), Checkpointing, Kubernetes/Yarn, ZooKeeper: (yes / **no** / don't
know)
- The S3 file system connector: (yes / **no** / don't know)
## Documentation
- Does this pull request introduce a new feature? (yes / **no**)
- If yes, how is the feature documented? (**not applicable** / docs /
JavaDocs / not documented)
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