missing output in XML files for np>1

[holke]

If an error occurs on rank k!=0, the message is lost because there is only a reduction on the test result to verify the test failed. On Jenkins we therefore see only the file and line where the test failed, not the details.

See also the corresponding PHIST issue:

https://bitbucket.org/essex/phist/issues/174/missing-test-output-in-xml-files

[holke]

@melven is this still an issue?

Can this be solved with one of the MPI listeners? @holke needs to investigate.

[melven]

This is still an issue but this is kind-of a decision about overhead and usability.

Very roughly without looking into the code again:
You could make some kind of allreduce of the error messages and join them to one (longer) error message... Jonas tried this once and reverted it later if I remember correctly...

• overhead: for >1k processes string parsing / concatenating will get more costly - and I'm not sure if you can do this only if an error occurs because there are things like expected failures, etc. (so you might end up doing this always for all expect/assert-statements)
• usability:
  • Printing all error messages easily gets ugly - you could try to combine them though - or print the error of the process with the smallest rank
  • And I'm reluctant to change the output because there might be other tools that parse the googletest output. (this is of course also a problem with the current approach where the real message is missing).