MaxConcurrency annotation

[smillidge]

Annotation to define max concurrency for access to a method or bean. This was first mooted on the EJB spec but adding to concurrency would mean this could be used generally across the platform.

See javaee/ejb-spec#9

Also see https://download.eclipse.org/microprofile/microprofile-fault-tolerance-2.1/apidocs/org/eclipse/microprofile/faulttolerance/Bulkhead.html

[smillidge]

If we have the new Async annotation I think we can have a very simple definition with just a single attribute for maxConcurrency and rely on Semaphore isolation. As the new Async annotation allows the developer to specify the specific ExecutorService which can be configured to have a maxAsync. Thread isolation can be acheived using the Async annotation and a ExecutorService with a configured maxAsync

[edburns]

Any word on getting this in for EE 11?

[smillidge]

it's tagged as a candidate for 3.1 which is the Jakarta EE 11 release. I don't think any work has been done yet though.

[njr-11]

It seems like the most important part of this is already covered by Asynchronous/executor with maxAsync, and all that remains is semaphore isolation. I am wondering what the value is of providing a @MaxConcurrency to enforce sempahore isolation when a user can already do that with java.util.concurrent.Sempahore and other classes of java.util.concurrent. How much benefit does the user get from having the Jakarta EE product provider hold onto the semaphore for them and automatically invoke it upon entry and exit from methods of a class? Is there more to this that I am not aware of?