CODEWITHSUNDEEP
c#multithreadingdelegates
illegal-immigrant
illegal-immigrant

Reputation: 8254

c# Delegate.BeginInvoke() and thread ID

let's say we have some simple code like this :

private static void Main()
{
    Console.WriteLine("Main thread {0}\n", Thread.CurrentThread.ManagedThreadId);

    Action asyncCaller1 = () => LongPerfomingTask(5);
    Action asyncCaller2 = () => LongPerfomingTask(3);

    var asyncResult1 = asyncCaller1.BeginInvoke(null, null);
    var asyncResult2 = asyncCaller2.BeginInvoke(null, null);

    asyncResult1.AsyncWaitHandle.WaitOne();
    asyncResult2.AsyncWaitHandle.WaitOne();

    Console.WriteLine("Done");
}

private static void LongPerfomringTask(int seconds)
{
    Thread.Sleep(TimeSpan.FromSeconds(seconds));

    Console.WriteLine("Thread {0} finished execution", Thread.CurrentThread.ManagedThreadId);
}

Delegate.BeginInvoke() does not create a thread, It's executing code in a caller's thread when it is in idle state, right?So, why the output of this sample application is like this :

Main thread 1

Thread 4 finished execution
Thread 3 finished execution
Done

Upvotes: 1

Views: 7726

Answers (2)

GregC
GregC

Reputation: 8007

@taras.roshko: Here's a resource to boost your understanding of ThreadPool: Chapter on Threading

Upvotes: 0

Jon Skeet
Jon Skeet

Reputation: 1503449

No, Delegate.BeginInvoke uses the thread pool. Always. There's no concept of "executing in the caller's thread when it's idle" unless you're thinking of adding tasks to a UI message queue... were you getting confused with Control.BeginInvoke / Dispatcher.BeginInvoke?

In this case you've got a console app - there's no message pumping going on to start with.

Upvotes: 6

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