That I did not try, but I just tried another, simpler program that does the communication the same way. It worked perfectly, and even showed the buffer size to be bigger (as almost all the messages were sent simultaneously) and they were processed line by line, as intended.

I'm now totally at loss what could cause that.

The most noticeable difference between the programs is that the non-working one is compiled with the MPI (openmpi) compiler (which adds some libraries and calls the GCC) instead of only gc++.

Confused, getting a headache,
Hannes