"George Pavlov" <gpavlov(at)mynewplace(dot)com> writes:
> And yes, redirect_stderr = on. I have no definitive way of reproducing
> it, just a vague one: "hit the server with lots of queries".
Hmm. If the messages are less than PIPE_BUF bytes long (4096 bytes on
Linux) then the writes are supposed to be atomic. Can you check whether
the interspersal cases involve messages whose total length (all lines)
exceeds 4K?
regards, tom lane