Performance problem with event publication lookup

[Groax256]

I believe there is a problem with implementation of org.springframework.modulith.events.core.DefaultEventPublicationRegistry.PublicationsInProgress.getPublication
As soon as listeners cannot keep up with event processing, it creates runaway performance issue.
Because the more publications are in progress the more time it spends on searching a TargetEventPublication, slowing down subsequent events.

Example processing speed, application was restarted around 9:30 and as more events were created the performance quickly plummeted

Hot spot when profiling application (other hot spots are also on getPublication but with different code paths):

Event is a simple Record with 2 fields, id and timestamp

Maybe there should be a Set/Map of events so the search is always O(1)?

I saw that 1.4 removed equals but the problem will still be the same because of current search algorithm complexity.

[odrotbohm]

I guess we can switch to a more optimal data structure for the checks. Do you have information about how many publications are currently in flight in that scenario?

[odrotbohm]

Never mind, I've got a local change flipping the implementation to a Map lookup and the benchmarks are dramatic (10000 publications in progress):

Baseline (1.3.4)

Benchmark                        Mode  Cnt        Score      Error  Units
….inProgressPublicationsAccess  thrpt   50  	312,155 ±    7,428  ops/s

Proposed fix

Benchmark                        Mode  Cnt        Score      Error  Units
….inProgressPublicationsAccess  thrpt   50  2328732,504 ± 7809,092  ops/s

[odrotbohm]

Please give the 1.4 snapshots a try and report any findings back. If we consider the fix appropriate, I am happy to port it back to 1.3.x.