heesung-sn opened a new pull request, #18254:
URL: https://github.com/apache/pulsar/pull/18254
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### Motivation
The index-based publisher stat aggregation(configured by
`aggregatePublisherStatsByProducerName`=false, default) can burst memory and
wrongly aggregate publisher metrics if each partition stat returns a different
size or order of the publisher list.
In the worst case, if there are many partitions and publishers created and
closed concurrently, the current code can create PublisherStatsImpl objects
exponentially, and this can cause a high GC time or OOM.
Issue Code reference:
https://github.com/apache/pulsar/commit/2c428f7fcc740525e8120566c0272fc863ffebf1#diff-02e50674125a597f8ae3405a884590759f2fdaa10104cea511d5ea44b6ff6490R224-R247
<!-- Explain here the context, and why you're making that change. What is
the problem you're trying to solve. -->
### Modifications
- Deprecated the `aggregatePublisherStatsByProducerName` broker config
because the default, the index-based aggregation is inherently wrong in a
highly concurrent producer environment(where the order and size of the
publisher stat list are not guaranteed to be the same). The publisher stats
need to be aggregated by a unique key, the producer
name(aggregatePublisherStatsByProducerName=true).
- If PublisherStatsImpl.publisherName happens to be null, it will aggregate
it with the stat object with "null" name. (However, this is unlikely because
the broker generates a globally unique name If not given.)
- Use HashMap instead List to aggregate publisher stats.
- Removed sorting from getPublisher(), as this can be expensive for a large
number of publishers.
- Simplified the stat aggregation code.
<!-- Describe the modifications you've done. -->
### Verifying this change
- [x] Make sure that the change passes the CI checks.
This change added unit tests.
### Does this pull request potentially affect one of the following parts:
*If the box was checked, please highlight the changes*
- [ ] Dependencies (add or upgrade a dependency)
- [x] The public API
- [ ] The schema
- [x] The default values of configurations
- [ ] The threading model
- [ ] The binary protocol
- [ ] The REST endpoints
- [ ] The admin CLI options
- [ ] Anything that affects deployment
### Documentation
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- [] `doc-not-needed` <!-- Your PR changes do not impact docs -->
- [ ] `doc-complete` <!-- Docs have been already added -->
### Matching PR in forked repository
PR in forked repository: https://github.com/heesung-sn/pulsar/pull/13
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