"Multiprocess signaling check:"

 is normal, debug message before(!) checking "registry sequence changed" and check "cache sequence changed".

It is displayed because the debug mode is enabled in the odoo config.

log_handler = :DEBUG
log_level = debug

If you do not want to clutter up the log with these unnecessary (in most cases), repeated, debugging messages, then add to odoo.conf the text "odoo.module.registry:INFO" in key log_handler.
Look at my config settings:

log_handler = werkzeug:WARNING,odoo.sql_db:INFO,odoo.modules.registry:INFO,:DEBUG
log_level = debug

Carefully, in different odoo versions some config keys can have different names.

But log messages:

" [Registry - old# 1 new# 1] [Cache - old# 1 new# 1]      >> database 2"

Hello chesucr,

By Setting only workers is not enough you have to configure few things, 

As you applied workers to 5 but make sure its based on some logic , see the link for more details.

https://www.odoo.com/forum/help-1/question/hardware-for-50k-website-visitors-128995#answer-129016

Many Thanks.