C backgroundworker completed error code

post for how to communicate between your BackgroundWorker and your main thread. Basically, you have to use a event that you set at the end of DoWork to signal that DoWork has completed. Stack Exchange network consists of 174 Q& A communities including Stack Overflow, the largest, most trusted online community for developers to learn, share their knowledge, and build their careers. I have this piece of code that uses a backgroundworker. The code does work but I have two questions: 1) There appears to be a disconnect between the percentage boxes that appear and actual data. I don' t use VB but I think you just need the standard VB. NET syntax for adding an event handler, which according to Google is; AddHandler event, AddressOf eventhandler So the code you need should be; AddHandler backgroundworker. DoWork, AddressOf DoWork. I wanted to fiddle around with the BackgroundWorker and Task classes, to see how I would implement a given task with these two techniques. So I created a new WinForms project, and implemented a si. has made the BackgroundWorker object available to us to simplify threading. This object is designed to simply run a function on a different thread and then call an event on your UI thread when it' s complete.

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  • Video:Completed backgroundworker error

    Code error completed

    The following code example demonstrates the basics of the BackgroundWorker class for executing a time- consuming operation asynchronously. The following illustration shows an example of the output. This code example is part of a larger example provided for the BackgroundWorker class. / / This event handler deals with the results of the / / background operation. void backgroundWorker1_ RunWorkerCompleted( Object^ / * sender* /, RunWorkerCompletedEventArgs^ e ) { / / First, handle the case where an exception was thrown. If the backgroundWorker Task is cancelled by the Application, then e. Cancelled is set to true and the block of code in it executed, The cancellation of Task is Sent from the DoWork Event to the RunWorkerCompleted Event. You can use the Result property to store any results from the DoWork and access it from Completed event. But if the background worker process got cancelled or an exception raised, the result won' t be accessible. BackgroundWorker myWorker = new BackgroundWorker( ) ; This works identically in both WinForms and WPF. Once you have a background worker to play with, you can begin making it work for you by assigning events to its handlers, and then calling its run method. The following code example demonstrates the use of the ReportProgress method to report the progress of an asynchronous operation to the user. You can start the BackgroundWorker again by calling RunWorkerAsync so long as the previous asynchronous operation has completed.

    It is not necessary to dispose it and create a new instance. Most likely, the BackgroundWorker is busy because the code in the DoWork event handler is still executing from a previous call to RunWorkerAsync. and when all operations have completed, put the focus on the modal progress form and have the user be able to click an OK button to then close the progress form and return control to the main app. I have a small app that I am working with to create LDIF files from text files. I have a pictureBox that has an animated GIF that will appear on the form when the LDIF are being created. Code Review Stack Exchange is a question and answer site for peer programmer code reviews. the status if the background process has completed successfully and. You saved me much time. This smells of magic, and I really wish. NET would throw a more on- the- nose exception ( " Result property may not be accessed when an exception was thrown by BackgroundWorker DoWork" ), rather than trying to do the right thing and just confusing matters. / / This event handler is where the actual, / / potentially time- consuming work is done.

    void backgroundWorker1_ DoWork( Object^ sender, DoWorkEventArgs^ e ) { / / Get the BackgroundWorker that raised this event. BackgroundWorker. This was introduced in. 0 The BackgroundWorker class provides a built- in wrapper for a worker thread. Communication between the main thread and the worker thread is asyncronous. Louis, I really appreciate the help. However, when I attempt to place a lock statement within the background worker it still errors out. Contrary to your statement, when the backgroundworker. RunWorkerAsync is called, it sees that backgroundworker. IsBusy = true and erros. In almost every real- world scenario, we also want to be notified when the background operation has completed. Also, most of the time, we want our “ handle the completion” code to run on the original context ( e. , a UI context so we could update the UI).

    The " Completed" event means that the DoWork code is done processing instead of " done doing something". I think TerryBozzio has a good suggestion. Call ReportProgress to fire the ProgressChanged event the first time counter = = 199. BackgroundWorker is a class in System. ComponentModel that allows you to run an operation on a separate, dedicated thread. Time- consuming operations like downloads and database transactions can cause your user interface ( UI) to seem as though it has stopped responding while they are running. RunWorkerCompleted + =. is not being invoked by you but by the BackgroundWorker. You' re only assigning the work for it to go do when it determines it is the appropriate time to do so. This site uses cookies for analytics, personalized content and ads. By continuing to browse this site, you agree to this use. A BackgroundWorker component executes code in a separate dedicated secondary thread.

    In this article, I will demonstrate how to use the BackgroundWorker component to execute a time consuming process while main thread is still available to the user interface. Any code that should run at the end of any BackgroundWorker should start at line # 39 ( in this example), leaving the last line as the IsInProgress reset call. EDIT Since the worker in this example is available at the ViewModel level, we can ( and should) eliminate the IsInProgress boolean altogether and simply refer to worker’ s IsBusy property. Here is the code exactly as I use it ( and it works 100% of the time). This is from an applicaiton that uses 2 background workers, one to open a binary data file, one to do a bunch of computing on some data. I' m only including the BackgroundWorkerLoad method and the key part to. Run code is shorter and simpler with less “ ceremony code”. Round 2: Errors - how to handle exceptions from the background thread code. Run code uses the more natural and less error- prone try/ catch blocks, and has less error- prone exception propagation. You can forego the background workers in favor of Tasks either via Task. Run or just async functions. They can be run independently, all at once or sequentially. The following example takes a collection of tasks and invokes them one after the other. Multi- threading with the BackgroundWorker By default, each time your application executes a piece of code, this code is run on the same thread as the application itself.

    This means that while this code is running, nothing else happens inside of your application, including the updating of your UI. Post your question and get tips & solutions from a community of 423, 426 IT Pros & Developers. It' s quick & easy. This content, along with any associated source code and files, is licensed under The Code Project Open License ( CPOL). Check before proceeding if the task in BackgroundWorker has completed. The preferred solution for this kind of problem is to use async- await. It might seem like black magic at first, but once you get the hang of it, it can be extremely powerful, and elegant. the above code works fine. But, the process in button1 was too heavy, i implemented Background worker and changed the button1_ click code to backgroundworker1_ Dowork event. The author posts the MSDN article verbatim " BackgroundWorker catches the exception and passes it into the RunWorkerCompleted event handler" and goes a step further to explain how wrapping code within DoWork( ) within a Try/ Catch block will cause the exception to be handled and therefore not unhandled and sent inside RunWorkerCompletedEventArgs.