CODEWITHSUNDEEP
c#multithreading
Ben Clarke
Ben Clarke

Reputation: 1061

Does threading in c# carry to other methods?

Issue

I am streaming my camera out and want it to run on a separate thread as my UI is freezing. If I start a Thread on the first method call, does the methods inside that method go into the new thread or the old thread?

This is my setup at the moment.

Code

When the user clicks 'Start Stream':

Thread thread = new Thread(new ThreadStart(StartNewStream));
thread.Name = "streammm";
thread.Start();

This calls 'StartNewStream' method which calls other methods:

cam.OnSampleAvailable += (s, e) =>
{
    lock (BusyLock)
      rtspRecord.PushVideo(e.Sample);
};

win.OnSamplesAvailable += (s, e) =>
{
    lock (BusyLock)
       rtspRecord.PushAudio(e.Samples);
};

Do the methods PushVideo and PushAudio get called in the UI thread or the newly created thread?

If I go into the PushVideo method and put the code:

Thread TR = Thread.CurrentThread;
string _name = TR.name;

The name is now null?

Anyone help on what I am doing wrong?

Upvotes: 1

Views: 58

Answers (2)

Thomas Hilbert
Thomas Hilbert

Reputation: 3629

Whichever thread invokes the OnSampleAvailable event or delegate will also execute its handlers. It does not matter which thread assigns the handlers.

You must understand what your code actually does:

cam.OnSampleAvailable += (s, e) =>
{
    lock (BusyLock)
        rtspRecord.PushVideo(e.Sample);
};

This does not call anything at first. It only assigns an anonymous method (s, e) => { ... } as a handler to the event cam.OnSampleAvailable.

The handler is not called here. The assignment completes and as the end of your StartNewStream method is reached, your new thread ends. Then, much later, there may be samples available on your cam. Whichever thread is responsible (we do not know) will invoke the cam.OnSampleAvailable event, and the handler (the anonymous method (s, e) => { ... } you assigned earlier) will be executed by that unknown thread.

Upvotes: 3

Scott Chamberlain
Scott Chamberlain

Reputation: 127563

It depends on the implementation of cam and win. Likey either those two events are running on their own thread pool thread or they may run on the UI thread if they are written in a way that knows how to capture the OperationContext

Upvotes: 0

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