debuging multi thread application problem

I have a windows application which have much intraction with the webservices. so I use backgroundworkers to make connection with webservices. I mostly handle DoWork and RunWorkerCompleted events to get the data in one and set in the other. and application is in debuging step now.

Just assume that the user loose the connection to internet when a backgroundworker is trying to connect to the server. I can catch the error but It's not enough. I also want to prevent RunWorderCompleted event if the worker could not get the right data from the internet. but I don't know how! throwing exceptions from worker's thread to the current thread seems imposible (tried it unsuccessfully) canceling the worker will not prevent RunworkerCompleted event to run. I am sure that every one who have experience to make such a program would use multi threads but I dont know how to handle the errors like this...

thank you in advance

regards

When you throw (or don't catch) and exception in the DoWork event it gets saved and will rethrow in the RunWorkerCompleted event, as a System.Reflection.TargetInvocationException when you try to get the result. The original exception is stored in the InnerException property. This is the ideal way of doing what you want because it gets the exception back to the GUI thread and you can then reliably inform the user of the problem via the GUI.

For example:

Which can be caught in the completed event handler:

...note the use of the InnerException.

oops! I have tried your code but the program stops in throwing line without catching in the RunWorkerCompleted event

throw new System.Net.WebException();

ashk1860 wrote:

thank you for your helpful reply. so I should ask one other question(don't mark as answer yet to don't loose attention). I am trying to throw all the exeptions to the main method and handle them there. but when the error occur the program will stop in thow line instead of going to the main. note that I manage to have try and catch in all of my blocks and throw all of them except main method but it don't go there. this was the reason that I thought it might be the threading problem

I check the app.config I didn't have that line. then I checked with and without it. nothing changed. how can I set the debugger to don't breake on exceptions when they are thrown it's strang because when I check throwing in my application, they just don't thrown when they are in DoWorker event.

it is just like what it should be! it don't work when it is in the other thead not with special exception. I mean I check it with trying to divide by zero in doWorder and in the main thread. it will thow in current thread and breaks in DoWorker event! totally different behavior with the same exception

With no Common Language Runtime Exceptions checked in the Exceptions dialog and no legacyUnhandledExceptionPolicy element in app.config, I cannot reproduce what you describe. Catching TargetInvocationException in the Completed event handler always catches any exception thrown in the DoWork handler, be it a divide by zero or a WebException. You have something like this for your Completed event handler :

here is one of my testing couple of events:

Weird! I use VS 2005