Windows Form hangs when running threads
- by Benjamin Ortuzar
JI have written a .NET C# Windows Form app in Visual Studio 2008 that uses a Semaphore to run multiple jobs as threads when the Start button is pressed.
It’s experiencing an issue where the Form goes into a comma after being run for 40 minutes or more. The log files indicate that the current jobs complete, it picks a new job from the list, and there it hangs.
I have noticed that the Windows Form becomes unresponsive when this happens. The form is running in its own thread.
This is a sample of the code I am using:
protected void ProcessJobsWithStatus (Status status)
{
int maxJobThreads = Convert.ToInt32(ConfigurationManager.AppSettings["MaxJobThreads"]);
Semaphore semaphore = new Semaphore(maxJobThreads, maxJobThreads); // Available=3; Capacity=3
int threadTimeOut = Convert.ToInt32(ConfigurationManager.AppSettings["ThreadSemaphoreWait"]);//in Seconds
//gets a list of jobs from a DB Query.
List<Job> jobList = jobQueue.GetJobsWithStatus(status);
//we need to create a list of threads to check if they all have stopped.
List<Thread> threadList = new List<Thread>();
if (jobList.Count > 0)
{
foreach (Job job in jobList)
{
logger.DebugFormat("Waiting green light for JobId: [{0}]", job.JobId.ToString());
if (!semaphore.WaitOne(threadTimeOut * 1000))
{
logger.ErrorFormat("Semaphore Timeout. A thread did NOT complete in time[{0} seconds]. JobId: [{1}] will start", threadTimeOut, job.JobId.ToString());
}
logger.DebugFormat("Acquired green light for JobId: [{0}]", job.JobId.ToString());
// Only N threads can get here at once
job.semaphore = semaphore;
ThreadStart threadStart = new ThreadStart(job.Process);
Thread thread = new Thread(threadStart);
thread.Name = job.JobId.ToString();
threadList.Add(thread);
thread.Start();
}
logger.Info("Waiting for all threads to complete");
//check that all threads have completed.
foreach (Thread thread in threadList)
{
logger.DebugFormat("About to join thread(jobId): {0}", thread.Name);
if (!thread.Join(threadTimeOut * 1000))
{
logger.ErrorFormat("Thread did NOT complete in time[{0} seconds]. JobId: [{1}]", threadTimeOut, thread.Name);
}
else {
logger.DebugFormat("Thread did complete in time. JobId: [{0}]", thread.Name);
}
}
}
logger.InfoFormat("Finished Processing Jobs in Queue with status [{0}]...", status);
}
//form methods
private void button1_Click(object sender, EventArgs e)
{
buttonStop.Enabled = true;
buttonStart.Enabled = false;
ThreadStart threadStart = new ThreadStart(DoWork);
workerThread = new Thread(threadStart);
serviceStarted = true;
workerThread.Start();
}
private void DoWork()
{
EmailAlert emailAlert = new EmailAlert ();
// start an endless loop; loop will abort only when "serviceStarted" flag = false
while (serviceStarted)
{
emailAlert.ProcessJobsWithStatus(0);
// yield
if (serviceStarted)
{
Thread.Sleep(new TimeSpan(0, 0, 1));
}
}
// time to end the thread
Thread.CurrentThread.Abort();
}
//job.process()
public void Process()
{
try
{
//sets the status, DateTimeStarted, and the processId
this.UpdateStatus(Status.InProgress);
//do something
logger.Debug("Updating Status to [Completed]");
//hits, status,DateFinished
this.UpdateStatus(Status.Completed);
}
catch (Exception e)
{
logger.Error("Exception: " + e.Message);
this.UpdateStatus(Status.Error);
}
finally {
logger.Debug("Relasing semaphore");
semaphore.Release();
}
I have tried to log what I can into a file to detect where the problem is happening, but so far I haven't been able to identify where this happens. Losing control of the Windows Form makes me think that this has nothing to do with processing the jobs. Any ideas?
