Break into a setTimeout every once in a while

- Allows the CPU to run other things that used the real `setTimeout`

- Fixes #1327
- See #1334
- Fixes jasmine/gulp-jasmine-browser#48

spec/core/ClearStackSpec.js

@@ -21,6 +21,30 @@ describe("ClearStack", function() {
     expect(setImmediate).toHaveBeenCalled();
   });
 
+  it("uses setTimeout instead of setImmediate every 10 calls to make sure we release the CPU", function() {
+    var setImmediate = jasmine.createSpy('setImmediate'),
+        setTimeout = jasmine.createSpy('setTimeout'),
+        global = { setImmediate: setImmediate, setTimeout: setTimeout },
+        clearStack = jasmineUnderTest.getClearStack(global);
+
+    clearStack(function() { });
+    clearStack(function() { });
+    clearStack(function() { });
+    clearStack(function() { });
+    clearStack(function() { });
+    clearStack(function() { });
+    clearStack(function() { });
+    clearStack(function() { });
+    clearStack(function() { });
+
+    expect(setImmediate).toHaveBeenCalled();
+    expect(setTimeout).not.toHaveBeenCalled();
+
+    clearStack(function() { });
+    expect(setImmediate.calls.count()).toEqual(9);
+    expect(setTimeout).toHaveBeenCalled();
+  });
+
   it("uses MessageChannels when available", function() {
     var fakeChannel = {
           port1: {},
@@ -37,6 +61,37 @@ describe("ClearStack", function() {
     expect(called).toBe(true);
   });
 
+  it("uses setTimeout instead of MessageChannel every 10 calls to make sure we release the CPU", function() {
+    var fakeChannel = {
+          port1: {},
+          port2: {
+            postMessage: jasmine.createSpy('postMessage').and.callFake(function() {
+              fakeChannel.port1.onmessage();
+            })
+          }
+        },
+        setTimeout = jasmine.createSpy('setTimeout'),
+        global = { MessageChannel: function() { return fakeChannel; }, setTimeout: setTimeout },
+        clearStack = jasmineUnderTest.getClearStack(global);
+
+    clearStack(function() { });
+    clearStack(function() { });
+    clearStack(function() { });
+    clearStack(function() { });
+    clearStack(function() { });
+    clearStack(function() { });
+    clearStack(function() { });
+    clearStack(function() { });
+    clearStack(function() { });
+
+    expect(fakeChannel.port2.postMessage).toHaveBeenCalled();
+    expect(setTimeout).not.toHaveBeenCalled();
+
+    clearStack(function() { });
+    expect(fakeChannel.port2.postMessage.calls.count()).toEqual(9);
+    expect(setTimeout).toHaveBeenCalled();
+  });
+
   it("calls setTimeout when onmessage is called recursively", function() {
     var fakeChannel = {
           port1: {},

spec/core/integration/EnvSpec.js

@@ -952,16 +952,15 @@ describe("Env integration", function() {
   });
 
   describe("with a mock clock", function() {
-    var originalTimeout;
-
     beforeEach(function() {
-      originalTimeout = jasmineUnderTest.DEFAULT_TIMEOUT_INTERVAL;
+      this.originalTimeout = jasmineUnderTest.DEFAULT_TIMEOUT_INTERVAL;
+      this.realSetTimeout = window.setTimeout;
       jasmine.clock().install();
     });
 
     afterEach(function() {
       jasmine.clock().uninstall();
-      jasmineUnderTest.DEFAULT_TIMEOUT_INTERVAL = originalTimeout;
+      jasmineUnderTest.DEFAULT_TIMEOUT_INTERVAL = this.originalTimeout;
     });
 
     it("should wait a specified interval before failing specs haven't called done yet", function(done) {
@@ -1079,7 +1078,8 @@ describe("Env integration", function() {
 
     it('should wait a custom interval before reporting async functions that fail to call done', function(done) {
       var env = new jasmineUnderTest.Env(),
-          reporter = jasmine.createSpyObj('fakeReport', ['jasmineDone', 'suiteDone', 'specDone']);
+          reporter = jasmine.createSpyObj('fakeReport', ['jasmineDone', 'suiteDone', 'specDone']),
+          realSetTimeout = this.realSetTimeout;
 
       reporter.jasmineDone.and.callFake(function() {
         expect(reporter.specDone).toHaveFailedExpecationsForRunnable('suite beforeAll times out', [
@@ -1109,6 +1109,11 @@ describe("Env integration", function() {
       jasmineUnderTest.DEFAULT_TIMEOUT_INTERVAL = 10000;
 
       env.describe('suite', function() {
+        env.afterAll(function() {
+          realSetTimeout(function() {
+            jasmine.clock().tick(10);
+          }, 100);
+        });
         env.describe('beforeAll', function() {
           env.beforeAll(function(innerDone) {
             jasmine.clock().tick(5001);

src/core/ClearStack.js

@@ -1,5 +1,7 @@
 getJasmineRequireObj().clearStack = function(j$) {
-  function messageChannelImpl(global) {
+  var maxInlineCallCount = 10;
+
+  function messageChannelImpl(global, setTimeout) {
     var channel = new global.MessageChannel(),
         head = {},
         tail = head;
@@ -22,25 +24,43 @@ getJasmineRequireObj().clearStack = function(j$) {
       }
     };
 
+    var currentCallCount = 0;
     return function clearStack(fn) {
-      tail = tail.next = { task: fn };
-      channel.port2.postMessage(0);
+      currentCallCount++;
+
+      if (currentCallCount < maxInlineCallCount) {
+        tail = tail.next = { task: fn };
+        channel.port2.postMessage(0);
+      } else {
+        setTimeout(fn);
+      }
     };
   }
 
   function getClearStack(global) {
+    var currentCallCount = 0;
+    var realSetTimeout = global.setTimeout;
+    var setTimeoutImpl = function clearStack(fn) {
+        Function.prototype.apply.apply(realSetTimeout, [global, [fn, 0]]);
+    };
+
     if (j$.isFunction_(global.setImmediate)) {
       var realSetImmediate = global.setImmediate;
       return function(fn) {
-        realSetImmediate(fn);
+        currentCallCount++;
+
+        if (currentCallCount < maxInlineCallCount) {
+          realSetImmediate(fn);
+        } else {
+          currentCallCount = 0;
+
+          setTimeoutImpl(fn);
+        }
       };
     } else if (!j$.util.isUndefined(global.MessageChannel)) {
-      return messageChannelImpl(global);
+      return messageChannelImpl(global, setTimeoutImpl);
     } else {
-      var realSetTimeout = global.setTimeout;
-      return function clearStack(fn) {
-        Function.prototype.apply.apply(realSetTimeout, [global, [fn, 0]]);
-      };
+      return setTimeoutImpl;
     }
   }