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

Do other frameworks (Tornado, Twisted, libuv/nodejs) have this functionality?

Hi Yury, no, I'm not familiar with the other frameworks (libuv doesn't have this). I'll need to look into it. If anybody else knows, please comment as well.

For server applications, the reverse proxy in front of the application can limit the connection limit.
It is a good workaround because the proxy is required (and most likely is used already) for any non-trivial server app.