SO_REUSEPORT

[Tomas Kvasnicka]

Hi!

I just wanted to add my 2 cents here….

- We are facing a very similar issue. During reloads of reuseport enabled configuration it sometimes happens that no workers accept new connections, bandwidth basically drops to 0 and it all reverts back to normal within few seconds. Hurts but not deadly.
- Our nginx uses the Intel QAT card which allows only a limited number of user-space processes using the card at any given moment. Therefore, our HUP handler has been patched quite a bit to shutdown workers one-by-one and then use the ngx_reap_child to start a new worker with updated configuration.
- We only use the reuseport option in combination with the QAT-based servers (servers with the patched HUP behaviour). Therefore, I am not yet sure if changes in the reload mechanism are the cause of the issue - still investigating.
- Thanks a lot for the “ss -nltp” tip.
- Currently testing the “iptables-drop-empty-ACKs” workaround.
- No two nginx masters are running simultaneously.
- Reducing the number of workers is also not happening, due to the changes described above - the new value of worker_processes will simply be ignored.

Thanks,
Tomas