I commited  asyncio_read_from_self.patch  into Tulip, Python 3.4 and 3.5. If someone is interested to work on more advanced enhancement, please open a new issue.

Oh by, a workaround is to limit the number of concurrent processes.

Without the patch, "./python test_subprocess_error.py 5 1000" (max: 5 concurrenet processes) emits a lot of "BlockingIOError: [Errno 11] Resource temporarily unavailable" message.

With the patch, I start getting messages with 140 concurrent processes, which is much better :-) IMO more than 100 concurrent processes is crazy, don't do that at home :-) I mean processes with a very short lifetime. The limit is the number of SIGCHLD per second, so the number of processes which end at the same second.