diff --git a/scm-core/src/main/java/sonia/scm/collect/IterableQueue.java b/scm-core/src/main/java/sonia/scm/collect/IterableQueue.java
index 353ccf919b..9d3c85bb90 100644
--- a/scm-core/src/main/java/sonia/scm/collect/IterableQueue.java
+++ b/scm-core/src/main/java/sonia/scm/collect/IterableQueue.java
@@ -47,11 +47,12 @@ import java.util.Iterator;
 import java.util.List;
 
 /**
- * A iterable queue. The queue can have multiple consumer {@link Iterator}, 
- * which can iterate over all items of the queue until the end of the queue is 
- * reached. The end of the queue if reached, if a producer call the method 
- * {@link #endReached()} and the iterator has consumed all items of the backend 
- * list.
+ * A iterable queue. The queue can have multiple parallel consumer 
+ * {@link Iterator}s, which can iterate over all items of the queue until the 
+ * end of the queue is reached. The end of the queue if reached, if a producer 
+ * call the method {@link #endReached()} and the iterator has consumed all items
+ * of the backend list. <strong>Warning: </strong> The queue iterator blocks 
+ * forever if the producer never call {@link #endReached()}.
  *
  * @author Sebastian Sdorra
  *
diff --git a/scm-core/src/main/java/sonia/scm/collect/QueueIterator.java b/scm-core/src/main/java/sonia/scm/collect/QueueIterator.java
index 10b3bf8a78..d4f5f4954a 100644
--- a/scm-core/src/main/java/sonia/scm/collect/QueueIterator.java
+++ b/scm-core/src/main/java/sonia/scm/collect/QueueIterator.java
@@ -33,15 +33,18 @@
 
 package sonia.scm.collect;
 
-//~--- JDK imports ------------------------------------------------------------
+//~--- non-JDK imports --------------------------------------------------------
 
 import com.google.common.collect.UnmodifiableIterator;
+
+//~--- JDK imports ------------------------------------------------------------
+
 import java.util.NoSuchElementException;
 import java.util.concurrent.TimeUnit;
 
 /**
- * Iterator for the {@link IterableQueue}. The {@link QueueIterator} should 
- * only be created from the {@link IterableQueue} by calling the 
+ * Iterator for the {@link IterableQueue}. The {@link QueueIterator} should
+ * only be created from the {@link IterableQueue} by calling the
  * {@link IterableQueue#iterator()}.
  *
  * @author Sebastian Sdorra
@@ -67,28 +70,30 @@ public final class QueueIterator<T> extends UnmodifiableIterator<T>
 
   /**
    * Returns the next item in the queue. This method will block until the next
-   * item is pushed to the queue, if the queue is empty and the end is not 
+   * item is pushed to the queue, if the queue is empty and the end is not
    * reached.
    *
    * @throws NoSuchElementException if the iteration has no more elements
-   * 
+   *
    * @return the next item in the queue
    */
   @Override
   public T next()
   {
-    if ( ! hasNext() ){
+    if (!hasNext())
+    {
       throw new NoSuchElementException("no more items in the queue");
     }
+
     return queue.get(index++);
   }
 
   //~--- get methods ----------------------------------------------------------
 
   /**
-   * Returns {@code true} {@code true} if the queue has more items. 
-   * This method will block until the next item is pushed to the queue, if the 
-   * queue is empty and the end is not 
+   * Returns {@code true} {@code true} if the queue has more items.
+   * This method will block until the next item is pushed to the queue, if the
+   * queue is empty and the end is not
    * reached.
    *
    *
@@ -122,7 +127,6 @@ public final class QueueIterator<T> extends UnmodifiableIterator<T>
     return result;
   }
 
-
   //~--- fields ---------------------------------------------------------------
 
   /** queue for the iterator */
diff --git a/scm-core/src/test/java/sonia/scm/collect/IterableQueueTest.java b/scm-core/src/test/java/sonia/scm/collect/IterableQueueTest.java
new file mode 100644
index 0000000000..ceadfe1aea
--- /dev/null
+++ b/scm-core/src/test/java/sonia/scm/collect/IterableQueueTest.java
@@ -0,0 +1,266 @@
+/**
+ * Copyright (c) 2010, Sebastian Sdorra All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice,
+ * this list of conditions and the following disclaimer. 2. Redistributions in
+ * binary form must reproduce the above copyright notice, this list of
+ * conditions and the following disclaimer in the documentation and/or other
+ * materials provided with the distribution. 3. Neither the name of SCM-Manager;
+ * nor the names of its contributors may be used to endorse or promote products
+ * derived from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE FOR
+ * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ * http://bitbucket.org/sdorra/scm-manager
+ *
+ */
+
+
+
+package sonia.scm.collect;
+
+//~--- non-JDK imports --------------------------------------------------------
+
+import com.google.common.collect.Lists;
+
+import org.junit.Test;
+
+import static org.junit.Assert.*;
+
+//~--- JDK imports ------------------------------------------------------------
+
+import java.util.List;
+import java.util.Random;
+import java.util.concurrent.ExecutionException;
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
+import java.util.concurrent.Future;
+
+/**
+ *
+ * @author Sebastian Sdorra
+ */
+public class IterableQueueTest
+{
+
+  /**
+   * Method description
+   *
+   */
+  @Test(expected = IllegalStateException.class)
+  public void testDuplicatedEndReached()
+  {
+    IterableQueue<String> queue = new IterableQueue<String>();
+
+    queue.endReached();
+    queue.endReached();
+  }
+
+  /**
+   * Method description
+   *
+   */
+  @Test
+  public void testIterator()
+  {
+    IterableQueue<String> queue = new IterableQueue<String>();
+
+    assertEquals(QueueIterator.class, queue.iterator().getClass());
+    queue.endReached();
+    assertNotEquals(QueueIterator.class, queue.iterator().getClass());
+  }
+
+  /**
+   * Method description
+   *
+   *
+   * @throws ExecutionException
+   * @throws InterruptedException
+   *
+   * @throws Exception
+   */
+  @Test
+  public void testMultiThreaded() throws Exception
+  {
+    testMultiThreaded(5, 10, false, 1000);
+  }
+
+  /**
+   * Method description
+   *
+   *
+   * @throws ExecutionException
+   * @throws InterruptedException
+   *
+   * @throws Exception
+   */
+  @Test
+  public void testMultiThreadedWithRandomSleep() throws Exception
+  {
+    testMultiThreaded(5, 10, true, 50);
+  }
+
+  /**
+   * Method description
+   *
+   */
+  @Test(expected = IllegalStateException.class)
+  public void testPushEndReached()
+  {
+    IterableQueue<String> queue = new IterableQueue<String>();
+
+    queue.push("a");
+    queue.endReached();
+    queue.push("b");
+  }
+
+  /**
+   * Method description
+   *
+   */
+  @Test
+  public void testSingleConsumer()
+  {
+    final IterableQueue<Integer> queue = new IterableQueue<Integer>();
+
+    new Thread(new IntegerProducer(queue, false, 100)).start();
+    assertResult(Lists.newArrayList(queue), 100);
+  }
+
+  /**
+   * Method description
+   *
+   *
+   * @param result
+   * @param itemCount
+   */
+  private void assertResult(List<Integer> result, int itemCount)
+  {
+    assertNotNull(result);
+    assertEquals(itemCount, result.size());
+
+    for (int c = 0; c < itemCount; c++)
+    {
+      assertEquals(Integer.valueOf(c), result.get(c));
+    }
+  }
+
+  /**
+   * Method description
+   *
+   *
+   * @param threads
+   * @param consumer
+   * @param randomSleep
+   * @param itemCount
+   *
+   * @throws Exception
+   */
+  private void testMultiThreaded(int threads, int consumer,
+    boolean randomSleep, int itemCount)
+    throws Exception
+  {
+    ExecutorService executor = Executors.newFixedThreadPool(threads);
+    List<Future<List<Integer>>> futures = Lists.newArrayList();
+
+    final IterableQueue<Integer> queue = new IterableQueue<Integer>();
+
+    for (int i = 0; i < consumer; i++)
+    {
+      Future<List<Integer>> future =
+        executor.submit(new CallableQueueCollector<Integer>(queue));
+
+      futures.add(future);
+    }
+
+    new Thread(new IntegerProducer(queue, randomSleep, itemCount)).start();
+
+    for (Future<List<Integer>> f : futures)
+    {
+      assertResult(f.get(), itemCount);
+    }
+  }
+
+  //~--- inner classes --------------------------------------------------------
+
+  /**
+   * Class description
+   *
+   *
+   * @version        Enter version here..., 13/03/01
+   * @author         Enter your name here...
+   */
+  private static class IntegerProducer implements Runnable
+  {
+
+    /**
+     * Constructs ...
+     *
+     *
+     * @param queue
+     * @param randomSleep
+     * @param itemCount
+     */
+    public IntegerProducer(IterableQueue<Integer> queue, boolean randomSleep,
+      int itemCount)
+    {
+      this.queue = queue;
+      this.randomSleep = randomSleep;
+      this.itemCount = itemCount;
+    }
+
+    //~--- methods ------------------------------------------------------------
+
+    /**
+     * Method description
+     *
+     */
+    @Override
+    public void run()
+    {
+      Random r = new Random();
+
+      for (int c = 0; c < itemCount; c++)
+      {
+        if (randomSleep)
+        {
+          try
+          {
+            Thread.sleep(r.nextInt(5));
+          }
+          catch (InterruptedException ex)
+          {
+            throw new RuntimeException("thread interrupted", ex);
+          }
+        }
+
+        queue.push(c);
+      }
+
+      queue.endReached();
+    }
+
+    //~--- fields -------------------------------------------------------------
+
+    /** Field description */
+    IterableQueue<Integer> queue;
+
+    /** Field description */
+    private int itemCount;
+
+    /** Field description */
+    private boolean randomSleep;
+  }
+}