Develop Reference

How to always running a control and all its child on a separate thread?

I have written an application which does lots of calculation on huge floating point numbers that makes the UI not responsive at all most of the time.
I am thinking of adding a status bar to this application and show some info about cpu load, used memory and a progress bar. Consider adding labels and progress bar to the statusbar as childs, how can I run this status bar on a separate thread which can be reliable to be responsive as much as possible?
I can already use progress bars and system diagnosting stuff normally. What I am looking for is your ideas and tips, possibly with some codes!
Update
I want the status bar shows real time cpu and memory details. How to workaround this?

You've got this the wrong way round. You should run all the UI in the same thread, and run the long calculation in a background worker. Trying to run UI in different threads within the same app just leads to pain.

Best thing is to just do a google search on BackgroundWorker. Here is one particular result on how to use it.
http://midnightprogrammer.net/post/Using-Background-Worker-in-C.aspx

Progress reporting to parent UI thread

apologies if I don't explain this clearly, but I'm writing an app which is causing me some problems with threading.
I have a UI which starts a System.Timers.Timer. Each time this timer elapses it triggers a workflow which opens a progress screen. To prevent another workflow starting before the last one has finished it locks an object on the main form.
This progress screen starts and reports the progress of, some file copying using FileCopyEX.
The problem I'm having is that the progress screen does not display until after the work flow has been completed.
Hopefully this will make it clearer:
Main Form
|
Timer Elapses
|
WorkFlow Starts
|
Progress Screen opens (errors which occur go back to the previous)
|
File copying occurs (progress reported back to progress screen)
If no errors, returns to main screen before next tick.
Until now I've only implemented very simple threading, so I'm not sure how best to implement this. I've tried starting the workflow on a BackGroundWorker to seperate it from the UI thread but it behaves the same.
Thanks

I suggest that you read about the BackgroundWorker. This has hooks for reporting progress.
Remember that system timers invoke its event handler on a non-UI thread. Whenever, you do something with the UI you must be on the UI thread.

Without the code I can only guess at the cause, but the likely reason is that the Progress window needs the UI to be pumping messages to appear - i.e. the UI thread needs to be running.
If the UI thread is busy running your workflow, then it won't get around to processing the displaying of your window until after that. You need to separate your flow so that the progress window is on your UI thread and the workflow is on a background thread.
Hope that makes sense!

progress bar in separate window

(WPF) We have been asked to build a little window that pops up when the app is busy (instead of or in addition to a wait cursor). We put a textblock in the window, and a ProgressBar with IsIndeterminate = true.
We call show on the little window, and then start up our long-running process, calling Close on the little window when we are through. However, during the long-running process, the ProgressBar does not show any activity, and the little window shows (Not Responding) in its title.
Is this even possible? A better idea?

You need to look into using another thread (or multiple threads) to do the heavy processing that could take longer than 100ms (100ms and above can cause this 'hanging' appearence before 'Not Responding' appears.)
You could create a new thread using a BackgroundWorker
object and subscribe to the OnProgressChanged event to indicate a progress bar update. This does not however get around the problem of accessing the main (UI) threads Progress Bar. You would have to check if an Invoke is required and then invoke a piece of code responsible for updating the Progress Bar.
Here is a StackOverflow question that shows a nice Extension Method in the accepted answer for invoking a method call on a control:
Invoking
Hopefully that helps!!

The problem is most likely that whatever is causing the app to be "busy" is being run in the main thread of the app. So, the app stops responding, including responding to layout and painting requests from the OS. So, when the app is "busy", it's too busy to paint the new window.
The solution is to move as much "heavy lifting" as possible into background threads, so the main thread and thus the UI remain responsive.

How to show progress status for a long-time-consuming function?

I have a windows form simply like this: 1) a button when clicked will perform an operation taking a long time to complete, 2) a label showing how much percentage of the progress is going on.
In the long operation I mentioned, I write the code to update the Text property of the label but it doesn't work!
Please help me to show the progress status correctly.

You can take a look at the BackgroundWorker class (see the MSDN overview). It allows you to run some long-running operation in background and report progress updates (percentage) and completion from the background task to the user interface. Note that you'll need to calculate the progress percentage yourself.
However, the BackgroundWorker class takes care of other tricky aspects, such as sending your progress reports to the main GUI thread (where you can safely update the user interface).

Your going to want to create a worker thread that performs the task and occasionally reports its update to the form thread. If you do all of your work in the UI thread, your UI will be locked and won't update the progress/label correctly.
Before you start the worker thread, calculate the total number of steps you believe the process will take. Start the worker thread. After each unit of work, you Invoke an update method on the UI thread to increment the process.
You'll want to look at the BackgroundWorker class.
If your application will have several of these, I recommend creating a process interface (e.g. IProgressProcess). This interface will contain methods for executing a process and reporting updates. You will create all of your process classes by implementing from this interface. Write a control that contains a progress bar and accepts an IProgressProcess through a constructor or property. It can then use your custom process to execute and move along the progress bar. Then you can have your custom progress control send events when the process is complete or canceled.

This usually happens if you try to update the UI on the same thread where the operation is occurring. There are a couple of different ways that you could accomplish this.
You can update the UI with the BeginInvoke method.
You can use a BackgroundWorker component.

The reason that you don't see any change, is that the change causes a message to redraw the label, but the main thread is busy working so it doesn't respond to the message.
The simplest solution would be to just call the Application.DoEvents after updating the label. That works as a quick fix for your immediate problem, but it still will leave the application unresponsive in any other way.
The good solution would to start the operation in a separate thread. That way your main thread is free to handle messages while the operation is running. However working in a separate thread means a litte more work when communicating with the UI. If you want to update controls, you have to use the Invoke method to start a method that runs in the main thread so that it has access to the controls. Alternatively you can just update a variable in the thread, and have a timer control that periodically checks for changes in the variable and updates the label accordingly.

C# Winforms How to update toolStrip in function

I'm building a UI for a program, and I can't figure out why my progress bar won't become visible after the convert button is clicked.
private void convertButton_Click(object sender, EventArgs e)
{
toolStripProgressBar.Visible = true;
...
toolStripProgressBar.Visible = false;
}
I ran into a similar problem with tkinter in Python, and I had to call a function to update the idle tasks. Is there a way to do this with windows forms without using threads?
Edit: On a side note, this is a progress bar in a toolStrip that also contains a label that gets updated with status bar text. Is there any way to get the label on the left side and the progress bar on the other instead of right next to each other on the left?

Well, there is a way to do this without using threads (Application.DoEvents) but I strongly recommend against you using it. Re-entrancy is nasty, and you really don't want the UI thread tied up at all.
Use BackgroundWorker instead - it's easy, and it's pretty much designed for progress bars. It takes the hassle out of using a separate thread and reporting progress back to the UI thread. No need for Control.Invoke etc - it takes care of that for you.
There are lots of tutorials for BackgroundWorker - it shouldn't take you too long to get going with it.

Per the question you asked for the way to do this WITHOUT threads, that is to do it with Application.DoEvents();. (Just add that call right after setting the progress bar as visible.)
Now I do agree with Jon Skeet though that BackgroundWorker is a better way of doing this, but it does use a separate thread.

You need to execute your process in a thread separate from the UI thread, and then have it periodically report back to the UI thread with it's progress. If your convert operation is working inside the UI thread, it will simply go unresponsive until the operation is complete.

The progress bar can only become visible when it is allowed to paint which occurs during the processing of messages. Message processing cannot normally happen while you are in the middle of an event handler. If you want the progress bar to show up you will have to set the visiblitity to true, start a background thread to complete the work and return from the handler.

I'm guessing the problem is that the "..." in your code is a long-running process. UI updates are not instantaneous, but must run through the message queue in windows and then be painted to the screen. The queue is pumped and painting takes place in the same thread as your events.
As a result, any long-running tasks need to be moved to a different thread. More than that, your line line of code needs to called after that thread terminates. Otherwise you set the progress bar and then immediately turn it off again.
One way to do that is with a BackgroundWorker control.

Here go two links trying to explain you how things work:
(1) (2)
Now, I will try to explain it as shortly as I can. Most of what happens inside a windows forms application happens in a single thread, usually the same thread Main() runs in. If you open Program.cs, you will see that Main() has a line that looks like the following:
Application.Run(new Form1());
If you debug the application at any moment and examine the call stack, you will see it will trace back to that Run method. This means that a Windows Forms application is in fact a continuous run of the Run method. So, what is Run doing? Run is eating a message queue through which Windows sends messages to it. Run then dispatches those messages to the correct controls, which themselves do things like add text which corresponds to the key being pressed, redraw themselves, etc. Notice that all this happens during and endless loop running alongside a single thread, so weather you are typing or simply moving the window around, loads of those messages are being passed onto the application, which in turn is processing them and reacting accordingly, all in that single thread. Controls can also send messages to themselves through the queue and even you can place messages in the pump via Control.BeginInvoke. One of the things those controls do is to raise events according to what happens. So, if you click a button, the code you've written to handle that click will ultimately and indirectly be run by the Application.Run method.
Now, what is happening with your code is that even though you are changing the visible status of your progress bar to visible and then updating its Value, you are then changing its visibility to false, all in the same method. This means that only after you leave the method, will Application.Run() be able to continue iterating and consuming the message queue, effectively asking the progress bar to update its display. When that happens, you've already left the progress bar's visibility to false, the last thing you did before exiting the method. DoEvents() is a quick and dirty workaround to your problem as it reads the messages in the queue and processes them. I don't really feel comfortable using it as it can bring reentrancy problems.
Using threads is a good solution, but I would recommend using a ThreadPool thread instead of a custom thread in this kind of situation, as I tend to use custom threads only in cases where I have a limited number of long lived threads and I need to control their life cycles. The easiest and most practical way to use threads is to use the BackgroundWorker component, even though I would recommend going through the pains of understanding how to do Windows Forms multithreading with delegates if you want to really understand what is going on.

My solution is to call refresh on the status strip.
I believe this causes the UI thread to repaint the status strip.
toolStripStatusBar1.PerformStep();
statusStrip1.Refresh();
This is for .NET 4.0. Even though this question is old it was the first I found on googling this issue.