Exception during data aggregation in parallel BP4 writing about adios2

[eisenhauer]

Just responding because nobody else had. This is not a familiar error to me, so no clue...

[berceanu]

Do we at least know if the message is coming from ADIOS2 or some other library in the stack?

[eisenhauer]

It looks to be from ADIOS. At least the "An existing exchange is still active" exception is possibly thrown by the ADIOS2 BP4 engine. In the ADIOS GIT history there is also a mention of a similar problem (and a fix for it being applied) 4 years ago. I agree with the suggestion that it's probably time to move to the BP5 engine. Better that than to go trying to diagnose problems in BP4.

[franzpoeschel]

Ok, then trying to reproduce this sounds like it's probably more effort than it's worth. Good to know that this error is not only unknown to me.
@berceanu I'd suggest upgrading to ADIOS2 v2.9 and openPMD-api 0.15 and using --openPMD.ext bp5 in order to activate the BP5 backend. Maybe even just using ADIOS2 v2.9 with BP4 might already help, but it might also not.