Executing More than 3 Futures does not work

Question

I m using dispatch library in my sbt project. When I initialize three future and run them it is working perfectly But I increase one more future then it goes to a loop.

My code:

    //Initializing Futures
    def sequenceOfFutures() ={

     var pageNumber: Int = 1
        var list ={Seq(Future{})}

        for (pageNumber <- 1 to 4) {
          list ++= {
            Seq(
              Future { 
              str= getRequestFunction(pageNumber); 
              GlobalObjects.sleep(Random.nextInt(1500)); 

              }
              )
          }
        }
    Future.sequence(list)
    }
Await.result(sequenceOfFutures, Duration.Inf)

And then getRequestionFunction(pageNumber) code:

def getRequestionFunction(pageNumber)={

  val h=Http("scala.org", as_str)

while(h.isComplete){

   Thread,sleep(1500);
}

}

I tried based on one suggestion from How to configure a fine tuned thread pool for futures?

I added this to my code:

import java.util.concurrent.Executors
import scala.concurrent._

implicit val ec = new ExecutionContext {
    val threadPool = Executors.newFixedThreadPool(1000);

    def execute(runnable: Runnable) {
        threadPool.submit(runnable)
    }

    def reportFailure(t: Throwable) {}
}// Still didn't work 

So when I use more than four Futures then it keeps await forever. Is there some solution to fix it?

But it didn't work Could someone please suggest how to solve this issue?