[sapphirecat]

Looks pretty nice. Some pictures are worth quite a few words.

Is this problem made worse by the ephemeral ports remaining unavailable after disconnect, because they're stuck in TIME_WAIT? Or does a modern TCP stack note a low RTT and release the port much sooner?

[kowsik]

You have to think about concurrency. If there were a total of 64K simultaneous requests to that physical instance, each of which is running 100+ apps because it's multi-tenant, this drastically reduces the number of ports available to each app. With evented IO, a socket could be open for 250 ms (db query taking time) that sucks up a port causing a potential DoS on the other apps.