Asyncio uses a pipe to wakeup event loop in cases of
1. Signal handlers (set_wakeup_fd)
2. Calling asyncio code from another thread

In both cases, it sends b'\0' to the pipe to wake up a loop.
If the pipe is full OSError is raised.
asyncio logs these exceptions in debug mode.
The logging can be omitted because if the pipe is full the loop wakes up and drains the pipe anyway.