Calling Blocking Java Library from Spray Route

[Kevin Meredith]

From my Scala code, I'm calling a Java library that blocks to download a document & parse it. Let's assume it's unreasonable to re-write the library.

The scala method's signature is: `def f: Int` (let's say that it downloads the library & returns an integer for failure or success - not a very good design, I'd say, but let's go with it).

Since the Java library is blocking, is there any value in wrapping this synchronous operation with `Future`'s? In particular, I'm thinking about how I'm going to call this `f` method from my `spray http` web service.

My concern is that, when I call this method in a spray route, will the web service only be able to handle 1 request per time if the java library is blocking?

[Age Mooij]

If you can't get rid of the blocking call by replacing the library with a better one, you can wrap the blocking stuff in bulkheaded async code, like simple Futures or actors. That's what most people will do. The only thing to watch out for is making sure you don't exhaust the thread pool so I'd recommend running blocking code in its own bulkheaded Akka dispatcher.

Hope this helps

Age

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[Kevin Meredith]

hi Age -

could you please recommend any reading on bulkheaded dispatcher? or maybe even some code demonstrating how to address my situation with blocking?

thanks