How to catch RejectedExecutionException when using Scala futures?

Question

Where should I catch RejectedExecutionExceptions when shutting down the executor ? I tried:

 future {
        Option(reader.readLine)
      } onComplete {
        case Success(v) =>
        case Failure(e) => e match {
          case ree: RejectedExecutionException =>
          // doesn't work
      }

and :

 try {
        future {
          Option(reader.readLine)
        } onComplete {
          ...
        }
      } catch {
        case ree: RejectedExecutionException =>
          // doesn't work
      }

also doesn't work. Still getting :

Exception in thread "pool-99-thread-1" java.util.concurrent.RejectedExecutionException
at java.util.concurrent.ThreadPoolExecutor$AbortPolicy.rejectedExecution(ThreadPoolExecutor.java:1768)
at java.util.concurrent.ThreadPoolExecutor.reject(ThreadPoolExecutor.java:767)
at java.util.concurrent.ThreadPoolExecutor.execute(ThreadPoolExecutor.java:658)
at scala.concurrent.impl.ExecutionContextImpl.execute(ExecutionContextImpl.scala:105)
at scala.concurrent.impl.CallbackRunnable.executeWithValue(Promise.scala:37)
at scala.concurrent.impl.Promise$DefaultPromise.tryComplete(Promise.scala:133)
at scala.concurrent.Promise$class.complete(Promise.scala:55)
at scala.concurrent.impl.Promise$DefaultPromise.complete(Promise.scala:58)
at scala.concurrent.impl.Future$PromiseCompletingRunnable.run(Future.scala:23)
at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908)
at java.lang.Thread.run(Thread.java:662)

Answer 1

It must be handled by RejectedExecutionHandler. Either java.util.concurrent.ThreadPoolExecutor.DiscardPolicy or by your custom implementation.

This executor silently passes over RejectedExecutionException:

val executorService = new ThreadPoolExecutor(1, 1, 0L, TimeUnit.MILLISECONDS, new LinkedBlockingQueue[Runnable], Executors.defaultThreadFactory, new DiscardPolicy)