Nginx: the old connection cannot be processed properly after reload

[chenyuezhou]

After reload nginx, the old fd closed, the rest of the data could not be sent properly due to Bad file descriptor.

The client's packets will be dropped by the new worker due to invalid initial packet.

[chenyuezhou]

The new worker is created first during the reload. If only dependent on the UDP binding process mechanism provided by reuseport the old connection may be hashed to the new worker by the kernel.