Add IsolateRunner as a helper around Isolate.

example/runner-pool.dart

+// Copyright (c) 2015, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+library dart.pkg.isolate.sample.runners;
+
+import "package:isolate/loadbalancer.dart";
+import "package:isolate/isolaterunner.dart";
+import "dart:async" show Future, Completer;
+
+
+void main() {
+  int N = 44;
+  var sw = new Stopwatch()..start();
+  // Compute fib up to 42 with 4 isolates.
+  parfib(N, 4).then((v1) {
+    var t1 = sw.elapsedMilliseconds;
+    sw.stop();
+    sw.reset();
+    print("fib#4(${N}) = ${v1[N]}, ms: $t1");
+    sw.start();
+    // Then compute fib up to 42 with 2 isolates.
+    parfib(N, 2).then((v2) {
+      var t2 = sw.elapsedMilliseconds;
+      sw.stop();
+      print("fib#2(${N}) = ${v2[N]}, ms: $t2");
+    });
+  });
+}
+
+// Compute fibonnacci 1..limit
+Future<List<int>> parfib(int limit, int parallelity) {
+  return LoadBalancer.create(parallelity, IsolateRunner.spawn).then(
+    (LoadBalancer pool) {
+      List<Future> fibs = new List(limit + 1);
+      // Schedule all calls with exact load value and the heaviest task
+      // assigned first.
+      schedule(a, b, i) {
+        if (i < limit) {
+          schedule(a + b, a, i + 1);
+        }
+        fibs[i] = pool.run(fib, i, load: a);
+      }
+      schedule(0, 1, 0);
+      // And wait for them all to complete.
+      return Future.wait(fibs).whenComplete(pool.close);
+    });
+}
+
+int computeFib(n) {
+  int result = fib(n);
+  return result;
+}
+
+int fib(n) {
+  if (n < 2) return n;
+  return fib(n - 1) + fib(n - 2);
+}