It's safe for Waker.on_receive() to drain all bytes.

By the the time Waker.wake() writes to the pipe, any shared state that
would trigger action on the Broker thread has already been updated, so
reading subsequent bytes caused by later Waker.wake() can't miss
anything.

This avoids spewing tons of logs messages every time there is a storm of
user-generated log messages.

econtext/core.py

@@ -670,7 +670,7 @@ class Waker(BasicStream):
         """
         Read a byte from the self-pipe.
         """
-        os.read(self.receive_side.fd, 1)
+        os.read(self.receive_side.fd, 256)
 
 
 class IoLogger(BasicStream):