Demonstration of Play akka-http handling of timeout

akka-http behaviour

sbt run and in another console: curl -i http://localhost:9000.

This produces a response after 20 seconds:

HTTP/1.1 503 Service Unavailable
Date: Sat, 11 Mar 2017 01:44:28 GMT
Content-Type: text/plain; charset=UTF-8
Content-Length: 105

The server was not able to produce a timely response to your request.
Please try again in a short while!%

This is not good.

netty behaviour

sbt -Duse-netty= run and in another terminal: curl -i http://localhost:9000. This produces no response, which is good.

Why it matters

There may be cases where producing a response simply takes too long, such as a transaction, an initial load or a background task.

And it may easily take over 20 seconds.

Backwards compatibility

There may be others who experience a similar problem and won't find out until they migrate.

My use case

In my particular use case I load in a bunch of reference data and do a computation that takes a while but enables my app to live without a database and keep it 100% Scala and 0% SQL. This computation will take 1 minute or more.

Both production, test and dev use cases have a similar problem: I go to the initial page / and it times out. In dev case I need to call this endpoint to just compile the app. Then I have to refresh again after a while (and I don't know after how long, since size of data/CPU availability availability changes), when I could've just waited for the request to complete and seen it complete loading successfully in my browser tab.