Generator-jhipster: Follow Dave Syer's advices to make Spring faster

[jdubois]

This should be done on the spring-boot_2.1.0 branch.

We should do a list of all the tips given by Dave Syer on https://spring.io/blog/2018/12/12/how-fast-is-spring and discuss them one-by-one, and then do small PRs to implement each of the ones we select.

[jdubois]

I'm doing this and I already have some nice results :-)

[jdubois]

I did the 4 most obvious tricks we could do. For the other points it's more complicated:

• several of them include adding arguments to the JVM, and we don't have much control on how the end-user sets up is IDE. Maybe we could do this only for Maven/Gradle.
• we could manually configure all beans, but then it would be a pain for our end-users when they want to add or configure more features, as they would lose all the auto-configuration and will need to do this manually like us.

[PierreBesson]

@jdubois arguments to the JVM could be setup on the docker image as well. As for the exploded jar and running with java -cp, this is already what jib does 😃!

[jdubois]

Thanks @PierreBesson good idea, I'm doing this!

[jdubois]

BTW I won't use -XX:TieredStopAtLevel=1 because this degrades performance later

[jdubois]

Closing this as the list is over!

[jdubois]

Bounty claimed: https://opencollective.com/generator-jhipster/expenses/6356