Multi group by caps at 256 groups

[flamurjahiri]

Mutiny's Multi.group().by() silently caps at 256 groups due to a hard-coded default buffer, causing downstream operators like flatMap to process only 256 items. This settings can be changed when using merge, but is it a desired behavior? Below are two examples how it is being stuck, and never completing, and when I use Integer.MAX_VALUE it is finishing all the items.

[flamurjahiri]

Hi @jponge ,
https://github.com/flamurjahiri/Mutiny---GroupBy
here is the reproducer.
All you need is to run :
https://github.com/flamurjahiri/Mutiny---GroupBy/blob/main/src/main/java/org/acme/Main.java

If you need anything else, let me know.

Thanks!

[jponge]

Can you please condense it into something with no entity types, etc? Just plain strings would be fine.

[flamurjahiri]

I updated the reproducer.
Also something weird happening is that in my production code when I use group().by().onItem().transformToUniAndMerge() -> this is only emitting the first 256 items and not any more items, however I can't reproduce here with reproducer, I can if I just hardcode the buffer size. But I think this reproducer will lead to that one.

If you need anything else, or if there is something i can do to help, feel free to ask.

[jponge]

Thanks