https://issues.apache.org/jira/browse/AMQNET-488
Apply fix for potential deadlock on transport dispose during failover.
diff --git a/src/main/csharp/Threads/CompositeTaskRunner.cs b/src/main/csharp/Threads/CompositeTaskRunner.cs
index d081d35..96305c6 100755
--- a/src/main/csharp/Threads/CompositeTaskRunner.cs
+++ b/src/main/csharp/Threads/CompositeTaskRunner.cs
@@ -17,6 +17,7 @@
using System;
using System.Collections.Generic;
+using System.Linq;
using System.Threading;
namespace Apache.NMS.ActiveMQ.Threads
@@ -185,21 +186,28 @@
private bool Iterate()
{
- lock(mutex)
- {
- foreach(CompositeTask task in this.tasks)
- {
- if(task.IsPending)
- {
- task.Iterate();
+ Task pendingTask = null;
- // Always return true here so that we can check the next
- // task in the list to see if its done.
- return true;
- }
- }
+ lock (mutex)
+ {
+ foreach (CompositeTask task in this.tasks)
+ {
+ if (task.IsPending)
+ {
+ pendingTask = task;
+ break;
+ }
+ }
+ }
+
+ if (pendingTask != null)
+ {
+ pendingTask.Iterate();
+ // Always return true here so that we can check the next
+ // task in the list to see if its done.
+ return true;
}
-
+
return false;
}
}
diff --git a/src/test/csharp/Threads/CompositeTaskRunnerTest.cs b/src/test/csharp/Threads/CompositeTaskRunnerTest.cs
index 133ac43..1f42934 100644
--- a/src/test/csharp/Threads/CompositeTaskRunnerTest.cs
+++ b/src/test/csharp/Threads/CompositeTaskRunnerTest.cs
@@ -15,6 +15,7 @@
* limitations under the License.
*/
+using System;
using System.Threading;
using Apache.NMS.ActiveMQ.Threads;
using NUnit.Framework;
@@ -24,7 +25,6 @@
[TestFixture]
public class CompositeTaskRunnerTest
{
-
class CountingTask : CompositeTask
{
private int count;
@@ -90,5 +90,59 @@
runner.RemoveTask(task1);
runner.RemoveTask(task2);
}
+
+ [Test]
+ public void CompositeTaskRunnerDoesntHoldLockWhileCallingIterate()
+ {
+ object lockObj = new object();
+
+ // Start a task running that takes a shared lock during it's iterate.
+ CompositeTaskRunner runner = new CompositeTaskRunner();
+ runner.AddTask(new LockingTask(lockObj));
+
+ // Start a separate thread that holds that same lock whilst manipulating the CompositeTaskRunner (See InactivityMonitor for real example).
+ AutoResetEvent resetEvent = new AutoResetEvent(false);
+
+ ThreadPool.QueueUserWorkItem(_ =>
+ {
+ for (int i = 0; i < 10000; i++)
+ {
+ lock (lockObj)
+ {
+ var countingTask = new CountingTask("task1", 100);
+ runner.AddTask(countingTask);
+ runner.RemoveTask(countingTask);
+ }
+ }
+
+ resetEvent.Set();
+ });
+
+ // Wait for the second thread to finish 10000 attempts.
+ Assert.That(resetEvent.WaitOne(TimeSpan.FromSeconds(10)), "The secondary lock user didn't finish 10000 iterations in less than 10 seconds. Probably dead locked!");
+ runner.Shutdown();
+ }
+
+ private class LockingTask : CompositeTask
+ {
+ private readonly object _lockObj;
+
+ public LockingTask(object lockObj)
+ {
+ _lockObj = lockObj;
+ IsPending = true;
+ }
+
+ public bool Iterate()
+ {
+ lock (_lockObj)
+ {
+ Thread.Sleep(10);
+ }
+ return true;
+ }
+
+ public bool IsPending { get; private set; }
+ }
}
-}
+}
\ No newline at end of file
