You are right. In case if User=manticore systemd uses it for both ExecStart and ExecStop.
Anyway, I see that in 3.6.0 systemctl stop manticore takes 3+ second and then fails with manticore.service: Failed with result 'exit-code':
[root@459fa65b8e4d /]# systemctl start manticore
[root@459fa65b8e4d /]# time systemctl stop manticore
real 0m3.128s
user 0m0.010s
sys 0m0.000s
[root@459fa65b8e4d /]# journalctl -u manticore|tail -10
Oct 20 07:30:50 459fa65b8e4d systemd[1]: Stopping Manticore Search Engine...
Oct 20 07:30:50 459fa65b8e4d searchd[286]: [Fri Oct 20 07:30:50.658 2023] [286] using config file '/etc/manticoresearch/manticore.conf' (360 chars)...
Oct 20 07:30:50 459fa65b8e4d searchd[286]: [Fri Oct 20 07:30:50.659 2023] [286] stop: successfully sent SIGTERM to pid 248
Oct 20 07:30:53 459fa65b8e4d searchd[286]: Manticore 3.6.0 96d61d8bf@210504 release
Oct 20 07:30:53 459fa65b8e4d searchd[286]: Copyright (c) 2001-2016, Andrew Aksyonoff
Oct 20 07:30:53 459fa65b8e4d searchd[286]: Copyright (c) 2008-2016, Sphinx Technologies Inc (http://sphinxsearch.com)
Oct 20 07:30:53 459fa65b8e4d searchd[286]: Copyright (c) 2017-2021, Manticore Software LTD (https://manticoresearch.com)
Oct 20 07:30:53 459fa65b8e4d systemd[1]: manticore.service: Control process exited, code=exited status=1
Oct 20 07:30:53 459fa65b8e4d systemd[1]: manticore.service: Failed with result 'exit-code'.
Oct 20 07:30:53 459fa65b8e4d systemd[1]: Stopped Manticore Search Engine.
while in 6.2.12 it stops much faster and doesn’t fail:
[root@02f99f47d491 /]# time systemctl stop manticore
real 0m0.126s
user 0m0.012s
sys 0m0.000s
[root@02f99f47d491 /]# journalctl -u manticore|tail -10
Oct 20 07:34:41 02f99f47d491 systemd[1]: Started Manticore Search Engine.
Oct 20 07:34:46 02f99f47d491 systemd[1]: Stopping Manticore Search Engine...
Oct 20 07:34:46 02f99f47d491 searchd[300]: [Fri Oct 20 07:34:46.866 2023] [300] using config file '/etc/manticoresearch/manticore.conf' (269 chars)...
Oct 20 07:34:46 02f99f47d491 searchd[300]: [Fri Oct 20 07:34:46.867 2023] [300] stop: successfully sent SIGTERM to pid 218
Oct 20 07:34:46 02f99f47d491 searchd[300]: Manticore 6.2.12 dc5144d35@230822 (columnar 2.2.4 5aec342@230822) (secondary 2.2.4 5aec342@230822)
Oct 20 07:34:46 02f99f47d491 searchd[300]: Copyright (c) 2001-2016, Andrew Aksyonoff
Oct 20 07:34:46 02f99f47d491 searchd[300]: Copyright (c) 2008-2016, Sphinx Technologies Inc (http://sphinxsearch.com)
Oct 20 07:34:46 02f99f47d491 searchd[300]: Copyright (c) 2017-2023, Manticore Software LTD (https://manticoresearch.com)
Oct 20 07:34:46 02f99f47d491 systemd[1]: manticore.service: Succeeded.
Oct 20 07:34:46 02f99f47d491 systemd[1]: Stopped Manticore Search Engine.