PriorityExecutor with ExecutorCompletionService, is it possible?

Question

I have implemented an PriorityExecutor based on http://funofprograming.blogspot.co.il/2013/11/priorityexecutorservice-for-java.html and Specify task order execution in Java

However I want to use an ExecutorCompletionService and hand it the PriorityExecutor

However I get the following execption:

Caused by: java.lang.ClassCastException: java.util.concurrent.ExecutorCompletionService$QueueingFuture cannot be cast to java.lang.Comparable
    at java.util.concurrent.PriorityBlockingQueue.siftUpComparable(PriorityBlockingQueue.java:347)
    at java.util.concurrent.PriorityBlockingQueue.offer(PriorityBlockingQueue.java:479)
    at java.util.concurrent.ThreadPoolExecutor.execute(ThreadPoolExecutor.java:1364)
    at java.util.concurrent.ExecutorCompletionService.submit(ExecutorCompletionService.java:188)
    at com.ibm.modmt.impl.sommosAlg.meta.PoolStrategy.multiSubmit(PoolStrategy.java:160)
    at com.ibm.modmt.impl.sommosAlg.meta.MultiSOMMOSTask.multiSubmit(MultiSOMMOSTask.java:157)
    at com.ibm.modmt.impl.sommosAlg.meta.MultiSOMMOSTask.call(MultiSOMMOSTask.java:85)
    at com.ibm.modmt.impl.sommosAlg.meta.MultiSOMMOSTask.call(MultiSOMMOSTask.java:1)
    at java.util.concurrent.FutureTask.run(FutureTask.java:262)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
    ... 1 more

seems that the completion service creates its own Future (a QueueFuture ) out of my Comaprable Future.

Anyone implemented PriorityExecutor with ExecutorCompletionService? Do I need to extend ExecutorCompletionService if so how?

Answer 1

I don't see any way to do it with the builtin impl. However, ExecutorCompletionService is fairly simple code and is GPL, so you could copy it for your own use and modify it to handle your custom Future.