Hey Nginx experts,

During nginx reload, while old and new worker processes are co-existing, new incoming HTTP request from the same client continues to be handled by the old worker process.

For example I only have 1 worker process configured:
2024-04-09 23:58:28.977492708
nobody 344 3.1 0.1 16228 9796 ? S 23:58 0:00 nginx: worker process
nobody 1912 0.0 0.1 16508 9900 ? R 23:58 0:00 nginx: worker process
admin 1917 0.0 0.0 3680 1996 pts/6 S+ 23:58 0:00 grep --color=auto nginx
root 27857 0.0 0.0 12252 7412 ? Ss 23:07 0:00 nginx: master process /usr/sbin/nginx -c /etc/nginx/nginx.conf -g pid /run/nginx.pid;

pid 344 is the old worker process and 1912 is for the newly created one.

And in log nginx-error.log:
2024/04/09 23:58:28 [debug] 1912#0: epoll add event: fd:7 op:1 ev:00002001
2024/04/09 23:58:28 [debug] 1912#0: epoll add event: fd:8 op:1 ev:00002001
2024/04/09 23:58:28 [debug] 1912#0: epoll add event: fd:9 op:1 ev:00002001
2024/04/09 23:58:28 [debug] 344#0: *3375 ssl new session: D7E3C47D:32:149
2024/04/09 23:58:28 [debug] 344#0: *3375 ssl new session: 1A1D45B1:32:149

New worker process 1912 has been created while the old process continues to handle new TLS session from client.

Is this the expected behavior? How can I make sure the nginx service has been completely reloaded with new config?

Thanks for your help!
Ziqian