I have an webapp in Payara 4.1.1.162 + JPA + Hibernate 4.3.
My webapp has more than 20 PUs, because it needs to look for data in many databases.
But these databases aren't neeeded at the same time, there are options in the menu that
use one or other database at this time. I would like to know if it is possible to configure
Payara/JPA/Hibernate to doesn't do the initial check of databases at deploy time, leaving
it for a time it will be needed at running time, on demand of first user interaction.
Informações: HHH000204: Processing PersistenceUnitInfo [
name: myPU1
...]
Informações: HHH000204: Processing PersistenceUnitInfo [
name: myPU2
...]
etc
This part of deployment is the main processing time, then the webapp is deployed
more than 4 minutes. If I disable the majority of the PUs, leaving just one, the deployment
is very fast.
I use JTA and not RESOURCE-LOCAL in persistence.xml for all databases.
PS: I sent this msg in Payara/Glassfish forum and they said me to send to Hibernate forum.

I'm not sure if you can delay the EMF creation. But you can break it into multiple services so, when you have to deploy one service, you don't have to wait that much. Breaking the monolith seems like a popular choice these days.

But my webapp is just one traditional ERP where I have one deployment and many enterprises using the same app/server, just the user is different.
Then, it is not possible to break the app in mini-apps, like microservices or something like that.