we observe that after several days in service, where the server is reloaded several hundred times a day, it eventually stops responding.

a reload completes, but still all connections time out.
a restart corrects the issue.

is there a limit to the number of times a server permits a reload before it is necessary to restart it.
when the problem starts, entries like the following appear in the nginx error log

ter process /usr/sbin/nginx -g daemon on; master_process on;: /build/nginx-5J5hor/nginx-1.18.0/debian/modules/nchan/src/store/memory/memst\
ore.c:701: nchan_store_init_worker: Assertion `procslot_found == 1' failed.
2020/08/31 12:07:18 [alert] 1451759#1451759: worker process 1500846 exited on signal 6 (core dumped)
2020/08/31 12:07:18 [alert] 1451759#1451759: shared memory zone "memstore" was locked by 1500846

i see no mention of this issue here. but i did note

https://github.com/slact/nchan/issues/446

versions:
root@nl12:~# uname -a
Linux nl12.dydra.com 5.4.0-42-generic #46-Ubuntu SMP Fri Jul 10 00:24:02 UTC 2020 x86_64 x86_64 x86_64 GNU/Linux
root@nl12:~# which nginx
/usr/sbin/nginx
root@nl12:~# /usr/sbin/nginx -v
nginx version: nginx/1.18.0 (Ubuntu)