We know odoo can use the dbfilter - in the config file - for it to choose the right database when a new request comes in.

But does it keep the database connection open after the request is fulfilled (in its registry object)?

Let's say I have a system with 50 databases and dbfilter=^%d$. Here odoo will use the subdomain as the database filter and process the request. But I would like to know if it will keep the database connection open as a registry object so that every other request the comes from the same subdomain later on, doesn't have to open the connection, again.

Asking this because what if in my multi tenant architecture, certain DB's are used much less frequently than the others. Will keeping the database connection open be an expense?

This question was asked on stackoverflow and on github

https://stackoverflow.com/questions/64169770/does-odoo-keep-a-database-connection-open-in-a-multitenant-system

https://github.com/odoo/odoo/issues/59046