From time to time, you need to update configuration HTTP server configuration. Apache HTTPD and NGINX offer graceful restart, Oracle HTTP Server 12c uses graceful mode for restarts by default, but there are no graceful restarts for OHS 11g.

And yet you can do a graceful restart with OHS 11g, and it's effortless. You just send USR1 signal to the HTTPD process, as on example below. 

#Send USR1 singal to HTTPD process
[oracle@oracle-webtier11 ~]$ kill -USR1 $(cat $INSTANCE_HOME/diagnostics/logs/OHS/ohs1/httpd.pid)
# Validating result 
[oracle@oracle-webtier11 ~]$ tail $INSTANCE_HOME/diagnostics/logs/OHS/ohs1/ohs1.log
[2020-02-26T16:07:42.5875-05:00] [OHS] [NOTIFICATION:16] [OHS-9999] [core.c] [host_id: oracle-webtier11.domain.com] [host_addr: 192.168.1.22] [pid: 65333] [tid: 140185203439488] [user: oracle] [VirtualHost: main]  SIGUSR1 received.  Doing graceful restart
[2020-02-26T16:07:43.8346-05:00] [OHS] [NOTIFICATION:16] [OHS-9999] [core.c] [host_id: oracle-webtier11.domain.com] [host_addr: 192.168.1.22] [pid: 65333] [tid: 140185203439488] [user: oracle] [VirtualHost: main]  WebLogic Server Plugin version 1.1 
[2020-02-26T16:07:43.9410-05:00] [OHS] [NOTIFICATION:16] [OHS-9999] [core.c] [host_id: oracle-webtier11.domain.com] [host_addr: 192.168.1.22] [pid: 65333] [tid: 140185203439488] [user: oracle] [VirtualHost: main]  Oracle-HTTP-Server/11.1.1.9.0 (Unix) mod_ssl/11.1.1.9.0 OtherSSL/0.0.0 mod_plsql/11.1.1.0.0 mod_onsint/2.0 configured -- resuming normal operations