Should observers of StartupEvent return promptly?

[pavelrappo]

Both the CDI specification and Quarkus source code suggest that an observer of StartupEvent should return promptly, not block indefinitely. For example, it seems inappropriate for such an observer to implement the application's main event loop. Is my understanding correct?

[cescoffier]

Yes, the startup event is invoked on the "main" thread, so blocking will put the rest of the application startup on hold.

What do you call the "main event loop"? Quarkus has a built-in event bus if you need on.

[pavelrappo]

Yes, the startup event is invoked on the "main" thread, so blocking will put the rest of the application startup on hold.

Could this be added to Quarkus' documentation and guides if it's not already there? It's a pretty important part of the contract.

What do you call the "main event loop"? Quarkus has a built-in event bus if you need on.

I should've just called it "application's main loop". Adding "event" made it confusing in this context. Here's what I meant:

while (!shutdown) {
   // do work
}