How does Quarkus handle simultaneous requests?

Question

I am wondering how Quarkus is handling simultaneous requests to for example a REST API with json-rest.

Example:

• REST API is called by lots of clients simultaneously
• REST API call calls other APIs
• REST API processes the response of the other called APIs and returns the processed response

Questions:

• Are the requests queued and processed one by one?
• Are requests rejected if the API is busy?
• Is handling parallelism offloaded to the infrastructure using tools like Istio?

Can someone please point me to some documentation about that or give an explanation? Thank you.

Answer 1

Quarkus uses Vert.x under the hood which implements an event loop. This means that it can handle thousands of the requests because its threads are not blocked.

You may read more about it in the Vert.x's documentation: https://vertx.io/docs/vertx-core/java/