I have been trying to work out why my background worker is 'finishing' its work when there is still a lot for it to do. I am actually in the process of refactoring the code for this app, so it did work in the past, but now I am unable to figure out what has gone wrong.
Specifically, the app should open Outlook and then perform a few checks. However, the background worker exits straight after Outlook is opened for no apparent reason (as you will se below there is still plenty of processing to be done).
This appears to be happening early on in the Start() method, directly after calling Process.Start() on Outlook.exe.
The code runs in this order:
calling the background worker - this was the user's choice from a radio set
....
else if (radioButton5.Checked == true)
{
textBox1.Text = "Please wait while your session restarts";
pageControl1.SelectedIndex = 10;
backgroundReset.RunWorkerAsync();
}
The do-work method
public void backgroundReset_DoWork(object sender, DoWorkEventArgs e)
{
backgroundReset.WorkerSupportsCancellation = true;
Session.Reset();
}
the reset session method starts by killing the current session ...
public static void Reset()
{
KillSession();
System.Threading.Thread.Sleep(5000);
Start();
// THE BACKGROUNDWORKER EXITS BEFORE HERE!
if (IsLoggedIn() == false)
{
return;
}
else
{
// Make sure Lync is open before finishing the process ...
var j = 0;
GetSession(Init.servers);
j = 0;
var checker = false;
checker = ProcessHandler.CheckRunning("lync.exe");
while (checker == false)
{
if (j == 100)
{
break;
}
Thread.Sleep(500);
checker = ProcessHandler.CheckRunning("lync.exe");
j++;
}
}
}
As you can see from the comment, the backgroundworder is calling RunWorkerCompleted way before the Reset() method has finished executing.
Below are the other methods called (kill, logoff, start):
KillSession logs the session of and then makes sure it is logged off
private static void KillSession()
{
if (sessionId != null)
{
LogOff();
for (int i = 0; i < 150; i++)
{
if (IsLoggedIn() == true)
{
Thread.Sleep(500);
}
else
{
break;
}
}
}
}
LogOff sends a Cmd command to log off the current session
public static void LogOff()
{
string strCmdIn = "/C LOGOFF " + sessionId + " /SERVER:" + serverName;
Cmd.Exec(strCmdIn);
}
Start() Simply opens Outlook, causing a Citrix session to also start. The app is definitely launching Outlook, but after that it doesn't reach either of the for statements - the BackgroundWorker just exits.
public static void Start()
{
Process.Start(appDataCitrix + "Outlook.exe");
for (int i = 0; i < 15; i++)
{
if (IsLoggedIn2() == false)
{
Thread.Sleep(1000);
}
else
{
break;
}
}
if (IsLoggedIn2() == false)
{
Process.Start(appDataCitrix + "Outlook.exe");
for (int i = 0; i < 10; i++)
{
if (IsLoggedIn2() == false)
{
Thread.Sleep(1000);
}
else
{
break;
}
}
}
}
Does anyone have any idea what is going on here? It is driving me crazy!
Many thanks
Update
The RunWorkerCompleted Method:
As far as my understanding goes, this has no baring on when the process will finish.
public void backgroundReset_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
{
if (Session.IsLoggedIn())
{
btnFailFinish.Visible = true;
label10.Text = Session.serverName;
pageControl1.SelectedIndex = 3;
}
else
{
pageControl1.SelectedIndex = 10;
pictureBox2.Visible = false;
textBox1.Text = "Double-click Outlook on your desktop to launch a new session.";
textBox15.Text = "Once you have done this please click Finish.";
pictureBox9.Visible = true;
}
}
This is probably because of an exception being thrown from within the start method.
You may either add a try / catch block all around this method and handle the error from within the catch, or check in the RunWorkerCompleted method if an exception occurred :
private void RunWorkerCompleted (object sender, RunWorkerCompletedEventArgs e)
{
if (e.Error != null)
{
// handle your exception here
}
}
Related
I work on console version of link tester.
I start the function on multiple threads but I can't cancel them by key pressing.
Have an idea how I can do that ?
try
{
Thread[] tr = new Thread[Variables.Threads];
int i = 0;
while (i < Variables.Threads && Variables.running)
{
tr[i] = new Thread(new ThreadStart(Program.Runner));
i++;
}
//Start each thread
foreach (Thread x in tr)
{
x.Start();
}
//Console.ReadKey();
Task.Factory.StartNew(() =>
{
while (Colorful.Console.ReadKey().Key != ConsoleKey.Escape);
Variables.running = false;
foreach (Thread x in tr)
{
x.Abort();
}
Program.Menu();
});
}
catch (Exception)
{
}
EDIT : When my threads are a near of end, all of my app don't move after
The console is a not a good environment to start learning multitasking, much less multithreading. My advise to learning Multitasking - and especially Multithreading - is the BackgroundWorker in a WindowsForms applciation. The event queue does the main thing of keeping your application alive, without blocking I/O. And while the BackgroundWorker is horribly dated and should be removed from production code, it is pretty good training wheels.
Also your current code is swallowing exceptions, including fatal ones. This is a cardinal sin of exception handling. Do not do that.
At the end of the day, you can only do cancelation checking and progress reporting between distinct lines of code. In this BGW example, I had the advantage that I had to write all the loops anyway - so deep cancelation checking and progress reporting was in the cards. But if you use "somebody elses code", chances are high you have to wait for one function call to return before you can report and check.
#region Primenumbers
private void btnPrimStart_Click(object sender, EventArgs e)
{
if (!bgwPrim.IsBusy)
{
//Prepare ProgressBar and Textbox
int temp = (int)nudPrim.Value;
pgbPrim.Maximum = temp;
tbPrim.Text = "";
//Start processing
bgwPrim.RunWorkerAsync(temp);
}
}
private void btnPrimCancel_Click(object sender, EventArgs e)
{
if (bgwPrim.IsBusy)
{
bgwPrim.CancelAsync();
}
}
private void bgwPrim_DoWork(object sender, DoWorkEventArgs e)
{
int highestToCheck = (int)e.Argument;
//Get a reference to the BackgroundWorker running this code
//for Progress Updates and Cancelation checking
BackgroundWorker thisWorker = (BackgroundWorker)sender;
//Create the list that stores the results and is returned by DoWork
List<int> Primes = new List<int>();
//Check all uneven numbers between 1 and whatever the user choose as upper limit
for(int PrimeCandidate=1; PrimeCandidate < highestToCheck; PrimeCandidate+=2)
{
//Report progress
thisWorker.ReportProgress(PrimeCandidate);
bool isNoPrime = false;
//Check if the Cancelation was requested during the last loop
if (thisWorker.CancellationPending)
{
//Tell the Backgroundworker you are canceling and exit the for-loop
e.Cancel = true;
break;
}
//Determin if this is a Prime Number
for (int j = 3; j < PrimeCandidate && !isNoPrime; j += 2)
{
if (PrimeCandidate % j == 0)
isNoPrime = true;
}
if (!isNoPrime)
Primes.Add(PrimeCandidate);
}
//Tell the progress bar you are finished
thisWorker.ReportProgress(highestToCheck);
//Save Return Value
e.Result = Primes.ToArray();
}
private void bgwPrim_ProgressChanged(object sender, ProgressChangedEventArgs e)
{
pgbPrim.Value = e.ProgressPercentage;
}
private void bgwPrim_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
{
pgbPrim.Value = pgbPrim.Maximum;
this.Refresh();
if (!e.Cancelled && e.Error == null)
{
//Show the Result
int[] Primes = (int[])e.Result;
StringBuilder sbOutput = new StringBuilder();
foreach (int Prim in Primes)
{
sbOutput.Append(Prim.ToString() + Environment.NewLine);
}
tbPrim.Text = sbOutput.ToString();
}
else
{
tbPrim.Text = "Operation canceled by user or Exception";
}
}
#endregion
However in your case, Multithreading seems unesseary. Multitasking without Threads would propably be better. Threads only help if you got a CPU bound task. And "checking links" sounds like a Network bound task. Threads have some extra headaches that you are better off avoiding.
My requirement is to insert item in a queue and process it but the items should be added first and after a while they should be processed (as some other things needs to be set before processing the items. Here is the coding I have done so far.
#region Variables Declarations
private Thread threadTask = null;
ConcurrentQueue<string> concurrentQueue = new ConcurrentQueue<string>();
string currentSeqNo;
string previousSeqNo = "-1";
#endregion
private void test1_Load(object sender, EventArgs e)
{
AddItems();
if (threadTask == null)
{
threadTask = new Thread(Kick);
Thread.Sleep(5000);
threadTask.Start();
}
}
private void AddItems()
{
for (Int64 i = 100000; i < 300000; i++)
{
concurrentQueue.Enqueue(i.ToString());
this.Invoke(new MethodInvoker(delegate()
{
label1.Text = i.ToString();
label1.Update();
}));
}
}
private void Kick()
{
while (true)
{
int recordCountNew = concurrentQueue.Count();
if (recordCountNew != 0)
{
RemoveItems();
}
}
}
private void RemoveItems()
{
string item;
while (concurrentQueue.TryDequeue(out item))
{
this.Invoke(new MethodInvoker(delegate()
{
label2.Text = item;
label2.Update();
}));
currentSeqNo = item; // second time does not start wil 100000
if (previousSeqNo != "-1")
{
if (long.Parse(currentSeqNo) != long.Parse(previousSeqNo) + 1)
{
Reconnect();
}
else
{
//Process item
previousSeqNo = currentSeqNo;
}
}
else
{
//Process item
previousSeqNo = currentSeqNo;
}
}
}
private void Reconnect()
{
currentSeqNo = "";
previousSeqNo = "-1";
string someItem;
while (concurrentQueue.Count > 0)
{
concurrentQueue.TryDequeue(out someItem);
}
this.Invoke(new MethodInvoker(delegate()
{
label1.Text = "";
label2.Text = "";
label1.Update();
label2.Update();
}));
AddItems();
if (threadTask == null)
{
threadTask = new Thread(Kick);
threadTask.Start();
}
}
private void button1_Click_1(object sender, EventArgs e)
{
Reconnect();
}
To reproduce the issue: Run the app and in the middle click on the button. Now the queue should again be started from 100000 but it shows the number somewhere greater than 100000.
Please advise how do I release all the resources to make a fresh start after clicking a button. Though I am setting them to default and also clearing the queue but it still shows the old values in currentSeqNo when 'RemoveItems' method is called.
What you see is a race condition between the Kick thread and the button click handler. When you press the button you execute Reconnect() in it you clean the queue and then call the AddItems() function. But all this time the Kick function tries to Dequeue and so you end up each time with an arbitrary amount of items in it. What you should do is to synchronize between these functions or prevent the Kick from executing while you are adding items.
Couple of comments:
1) You Kick() method have an infinite loop, that too without sleep. Every thread started will keep on running as you didn't have a scope for thread to come out.
You can have a member variable like bKeepRunning with default value as true. Set that variable to false in beginning of Reconnect() function. Something like:
private void Kick()
{
while (bKeepRunning)
{
int recordCountNew = concurrentQueue.Count();
if (recordCountNew != 0)
{
RemoveItems();
}
}
}
Why do you have Thread.Sleep(5000); in test1_Load()? I dont think that is needed.
I made small change in your code, something like:
private void AddItems()
{
for (Int64 i = 100000; i < 300000; i++)
{
concurrentQueue.Enqueue(i.ToString());
this.Invoke(new MethodInvoker(delegate()
{
label1.Text = i.ToString();
label1.Update();
}));
if (i < 100004)
Thread.Sleep(1000);
}
}
private void Kick()
{
while (bKeepRunning)
{
int recordCountNew = concurrentQueue.Count();
if (recordCountNew != 0)
{
RemoveItems();
}
}
}
private void Reconnect()
{
currentSeqNo = "";
previousSeqNo = "-1";
bKeepRunning = false;
threadTask = null;
string someItem;
while (concurrentQueue.Count > 0)
{
concurrentQueue.TryDequeue(out someItem);
}
this.Invoke(new MethodInvoker(delegate()
{
label1.Text = "";
label2.Text = "";
label1.Update();
label2.Update();
}));
Thread.Sleep(2000);
AddItems();
bKeepRunning = true;
if (threadTask == null)
{
threadTask = new Thread(Kick);
threadTask.Start();
}
}
It helped me to see that value is starting from 100000. You can try the same at your end.
Note: I have stopped thread and restarted after clicking on button. Hence i dont see any flaw in your code as such. It just runs fast so that you are not able to realize start values.
You should make UI thread and threadTask thread sync, just use ManualResetEventSlim Signal Construct to, like this:
static ManualResetEventSlim guard = new ManualResetEventSlim(true);
private void button1_Click_1(object sender, EventArgs e)
{
guard.Reset();
Reconnect();
guard.Set();
}
private void RemoveItems()
{
string item;
while (concurrentQueue.TryDequeue(out item))
{
guard.Wait();
//......
}
}
see:
ManualResetEventSlim Class
Perhaps I am over thinking this but I have a number of threads doing a rather lengthy process and I want to be able to cleanly abort them if necessary. This is primarily because I don't want to start new threads until the old ones are finished. Is there a way to tell via Event or other method that a thread is fully aborted? Or should I not worry about this? Currently I have code in my abort method as follows:
private void AbortProcessing()
{
if (!Processing) return;
StopFlag = true;
for (int x = 0; x < MaxThreads; x++)
{
try
{
BW[x].CancelAsync();
}
catch { }
//Processing = false;
}
bool aborted = false;
while (!aborted)
{
aborted = true;
for (int x = 0; x < MaxThreads; x++)
{
if (BW[x].IsBusy) aborted = false;
}
Thread.Sleep(100);
}
}
The IsBusy is always true, forever, after signalling abort so this doesn't work. Any suggestions?
try this:Simple Sample for this
Thread o;
private void button1_Click(object sender, EventArgs e)
{
ThreadStart starter = ThreaadFunction;
starter += () => {
//this is this event you want to do any thing after a threaad finished the job
};
o = new Thread(starter) {IsBackground =true };
o.Start();
}
public void ThreaadFunction()
{
Thread.Sleep(1000);
// what you do in thread
}
}
I am implementing a preemptive, exclusive function in a multithreaded environment, where if a cancel request occurs even when the function is not running, when the function does run, it knows about this cancel request and does not run. I came across various different ways to do this in C# using ManualResetEvent and the like(something like the answer to this question Synchronizing a Timers.Timer elapsed method when stopping), however I was wondering if something as simple as what I am doing in the code below would suffice. Are there any inadvertent bugs that I am introducing here?
bool cancel = false;
bool running = false;
object Lock = new object();
void PremptiveExclusiveFunction() {
lock(Lock) {
if(running)
return;
running = true;
}
for(int i=0; i < numIter; i++) {
lock(Lock) {
if(cancel) {
cancel = false;
running = false;
return;
}
}
// iteration code
}
lock(Lock) {
running = false;
}
}
void Stop() {
lock(Lock) {
cancel = true;
}
}
As far as I know, this seems to handle my 3 requirements:
1. ability to preempt
2. exclusivity in time, where this only copy of this function can be running
3. a cancel request not being lost because Stop is called before PreemptiveExclusiveFunction
I'd be grateful if more experienced minds could point out if I am indeed missing something.
Entire function body can be locked to eliminate the running boolean:
object #lock = new object();
volatile bool cancel = false;
void Function () {
if (!Monitor.TryEnter(#lock))
return;
try {
for (var i = 0; i < 100; i++) {
if (cancel) {
cancel = false;
return;
}
// code
}
} finally {
Monitor.Exit(#lock);
}
}
void Stop () {
cancel = true;
}
+ Notice the volatile keyword:
http://msdn.microsoft.com/en-us/library/vstudio/x13ttww7(v=vs.100).aspx
I'm trying to let a program post a bunch of text. The user enters text, the amount of messages and how fast these must be delivered. While the program is busy, the button text needs to be "Stop" instead of "Start". When you press the button to force it to stop after you've initially launched it, the text changes back to "Start", but this doesn't happen when the program stops after the given amount of messages are delivered, even though the code is in place and doesn't generate an error.
I have a feeling that this is because of the text not updating for some reason. I've tried to flush it with Invalidate() and Update(), but this isn't working. How to fix this?
Here is the code:
private void button1_Click(object sender, EventArgs e)
{
if (button1.Text == "Start")
{
isEvil = true;
button1.Text = "Stop";
Thread t = new Thread(StartTyping);
t.Start(textBox1.Text);
}
else
{
isEvil = false;
button1.Text = "Start";
}
}
private void StartTyping(object obj)
{
string message = obj.ToString();
int amount = (int)numericUpDown2.Value;
Thread.Sleep(3000);
for (int i = 0; i < amount; i++)
{
if (isEvil == false)
{
//////This does NOT work
//button1.Text = "Start";
//button1.Invalidate();
//button1.Update();
//button1.Refresh();
//Application.DoEvents();
break;
}
SendKeys.SendWait(message + "{ENTER}");
int j = (int)numericUpDown1.Value * 10;
Thread.Sleep(j);
}
}
You have four answers telling you to update UI stuff from the UI thread, but none of them address the logic flow problem with your code.
The reason why it doesn't happen is because it only happens in the for-loop when isEvil is false. When does isEvil get set to false? Only when you click "Stop", and nowhere else.
If you want the button to go back to "Start" after the thread finishes, without clicking "Stop", then you need to add code after the loop to do that, independent of the value of isEvil: (piggybacking off of VoidMain's answer)
private void StartTyping(object obj)
{
string message = obj.ToString();
int amount = (int)numericUpDown2.Value;
Thread.Sleep(3000);
for (int i = 0; i < amount; i++)
{
if (isEvil == false)
{
if (button1.InvokeRequired)
{
button1.BeginInvoke( new Action(() => { button1.Text = "Start"; }) );
}
else
{
button1.Text = "Start";
}
break;
}
SendKeys.SendWait(message + "{ENTER}");
int j = (int)numericUpDown1.Value * 10;
Thread.Sleep(j);
}
if (button1.InvokeRequired)
{
button1.BeginInvoke( new Action(() => { button1.Text = "Start"; }) );
}
else
{
button1.Text = "Start";
}
}
Now you have duplicated code, so you might want to split it off into a separate method.
You need to be on the UI thread to update the UI.
Try something called the SynchronizationContext. There are plenty of examples when you google it.
If you're in WPF or Silverlight, you could use the Dispatcher. Again, lots of examples if you search those keywords in google or StackOverflow.
You must update your controls from the UI thread. This is how you would do it for winforms.
for (int i = 0; i < amount; i++)
{
if (isEvil == false)
{
button1.Invoke(new Action(() => button1.Text = "Start"));
break;
}
SendKeys.SendWait(message + "{ENTER}");
int j = (int)numericUpDown1.Value * 10;
Thread.Sleep(j);
}
This will block till button1 get's its text updated. If you don't want it to block, replace Invoke with BeginInvoke
Your best bet is to use a BackgroundWorker. It's a bit too wieldy to add a concise example here but there's a decent tutorial from O'Reilly
Something like this (not tested) should work:
private void StartTyping(object obj)
{
string message = obj.ToString();
int amount = (int)numericUpDown2.Value;
Thread.Sleep(3000);
for (int i = 0; i < amount; i++)
{
if (isEvil == false)
{
if(button1.InvokeRequired)
{
button1.BeginInvoke( new Action(() => { button1.Text = "Start"; }) );
}
else
{
button1.Text = "Start";
}
break;
}
SendKeys.SendWait(message + "{ENTER}");
int j = (int)numericUpDown1.Value * 10;
Thread.Sleep(j);
}
}