thundering herd; bleh

[brad]

Imagine the following scenario:

• Parent process opens listening socket, but will never accept() on it. Opening in parent so future forked child processes will inherit the fd, and because it's a low port (perhaps) and we want to open it before we drop root.
• Child processes (one per CPU) inherit listening fd, but they're event-based, handling many connections each, so they can't do a blocking accept() on it...

See where this is going? :-)

• So if each child has readability of that listening socket fd in its select/epoll/queue set, guess what? Thundering herd. The kernel wakes up all processes, but only one accepts the new client connection.

So instead I guess I have to...

• have a socketpair between parent and each child for communication,
• watch readability of the listening fd in parent process,
• on readability, send a message to "best" child (for some definition of best) to accept on the listening socket which it has, but isn't watching readability on.
• perhaps have children tell the parent process when connections go away, so parent knows approximate load on each child.

Feels kinda lame that I have to do this.

Any better suggestions?