I'd like to re-open the discussion on pause_server/resume_server that's been discussed here:

https://groups.google.com/forum/?utm_source=digest&utm_medium=email#!topic/python-tulip/btGHbh5kUUM

with PR:

https://github.com/python/asyncio/pull/448

We would like to set a max_connection parameters to a listening socket. Whenever it reaches this number with open accepted sockets, it stops accepting new connections until a user request is served, response sent back, and the connection closed. This is useful for a web application where the more user requests accepted and processed in-flight isn't necessarily better for performance. It would be great if we could dynamically change this value as well.

Some more detailed behavior:

- it can be either a per loop parameter, or per server parameter
- the number of currently open accepted connections is counted against this limit
- if max connection is reached, remove the listening socket from the loop so it back pressures new connections to kernel and other processes can take them
- when total number of accepted connections drops below max connection, put the listening socket back in the loop
- it can be dynamically configured but has no effect on currently already accepted connections (useful for graceful shutdown)

Lisa