Remove ThreadPoolExecutor fallback in ExecutionContextImpl

The method createDefaultExecutorService had a fallback if the creation
of a ForkJoinPool didn't succeed. This was necessary, because Scala
shipped its own version of FJP, and the dependency on sun.misc.Unsafe
(which is not an "offical" official API) made portability slightly
questionable.

Now that we can assume that FJP is supplied by the JDK, this concern
goes away.

1 files changed, 12 insertions, 31 deletions

diff --git a/src/library/scala/concurrent/impl/ExecutionContextImpl.scala b/src/library/scala/concurrent/impl/ExecutionContextImpl.scala
index c98746a98d..4cb5f51e62 100644
--- a/src/library/scala/concurrent/impl/ExecutionContextImpl.scala
+++ b/src/library/scala/concurrent/impl/ExecutionContextImpl.scala
@@ -8,13 +8,10 @@
 
 package scala.concurrent.impl
 
-
-
-import java.util.concurrent.{ ForkJoinPool, ForkJoinWorkerThread, ForkJoinTask, LinkedBlockingQueue, Callable, Executor, ExecutorService, Executors, ThreadFactory, TimeUnit, ThreadPoolExecutor }
+import java.util.concurrent.{ ForkJoinPool, ForkJoinWorkerThread, ForkJoinTask, Callable, Executor, ExecutorService, Executors, ThreadFactory, TimeUnit }
 import java.util.concurrent.atomic.AtomicInteger
 import java.util.Collection
 import scala.concurrent.{ BlockContext, ExecutionContext, Awaitable, CanAwait, ExecutionContextExecutor, ExecutionContextExecutorService }
-import scala.util.control.NonFatal
 import scala.annotation.tailrec
 
 
@@ -57,7 +54,7 @@ private[concurrent] object ExecutionContextImpl {
     }
 
     // As per ThreadFactory contract newThread should return `null` if cannot create new thread.
-    def newThread(runnable: Runnable): Thread = 
+    def newThread(runnable: Runnable): Thread =
       if (reserveThread())
         wire(new Thread(new Runnable {
           // We have to decrement the current thread count when the thread exits
@@ -80,7 +77,7 @@ private[concurrent] object ExecutionContextImpl {
                   } finally {
                     isdone = true
                   }
-                
+
                 true
               }
               override def isReleasable = isdone
@@ -123,33 +120,17 @@ private[concurrent] object ExecutionContextImpl {
                                                                       prefix = "scala-execution-context-global",
                                                                       uncaught = uncaughtExceptionHandler)
 
-    try {
-      new ForkJoinPool(desiredParallelism, threadFactory, uncaughtExceptionHandler, true) {
-        override def execute(runnable: Runnable): Unit = {
-            val fjt: ForkJoinTask[_] = runnable match {
-              case t: ForkJoinTask[_] => t
-              case r                  => new ExecutionContextImpl.AdaptedForkJoinTask(r)
-            }
-            Thread.currentThread match {
-              case fjw: ForkJoinWorkerThread if fjw.getPool eq this => fjt.fork()
-              case _                                                => super.execute(fjt)
-            }
+    new ForkJoinPool(desiredParallelism, threadFactory, uncaughtExceptionHandler, true) {
+      override def execute(runnable: Runnable): Unit = {
+        val fjt: ForkJoinTask[_] = runnable match {
+          case t: ForkJoinTask[_] => t
+          case r                  => new ExecutionContextImpl.AdaptedForkJoinTask(r)
+        }
+        Thread.currentThread match {
+          case fjw: ForkJoinWorkerThread if fjw.getPool eq this => fjt.fork()
+          case _                                                => super.execute(fjt)
         }
       }
-    } catch {
-      case NonFatal(t) =>
-        System.err.println("Failed to create ForkJoinPool for the default ExecutionContext, falling back to ThreadPoolExecutor")
-        t.printStackTrace(System.err)
-        val exec = new ThreadPoolExecutor(
-          desiredParallelism,
-          desiredParallelism,
-          5L,
-          TimeUnit.MINUTES,
-          new LinkedBlockingQueue[Runnable],
-          threadFactory
-        )
-        exec.allowCoreThreadTimeOut(true)
-        exec
     }
   }