Sometimes when we run "systemctl restart koha-commmon" the SIP server doesn't get restarted but might just get stopped leading to longer than expected downtime. There is probably some sort of race condition.
I am not sure if this is still valid, but at least there is no mention of SIP in the output of koha-common restart: sudo service koha-common restart Restarting Koha ILS: koha-commonStopping Plack daemon for kohadev:. Stopping Z39.50/SRU daemon for kohadev:. Stopping Koha worker daemon for kohadev (default):. Stopping Koha worker daemon for kohadev (long_tasks):. Stopping Koha indexing daemon for kohadev:. Successfully stopped all services for instance koha-common:. Starting Plack daemon for kohadev:. Starting Z39.50/SRU daemon for kohadev:. Starting Koha worker daemon for kohadev (default):. Starting Koha worker daemon for kohadev (long_tasks):. Starting Koha indexing daemon for kohadev:. .
I've seen this too, I think it happens when there are a lot of SIP workers/processes and it takes some time for them to kill.