What's the best way to pass data between concurrent threads in .NET?

.net, concurrency, multithreading

Solution

If the pieces of data are independant then treat the pieces of data as work items to be processed by a pool of threads. Use the thread pool and `QueueUserWorkItem` to post the data to the thread(s). You should get better scalability using a pool of symmetric threads and limiting the amount of synchronisation that has to occur between the producer and consumer(s).

For example (from MSDN):

    TaskInfo ti = new TaskInfo("This report displays the number {0}.", 42);

    // Queue the task and data.
    if (ThreadPool.QueueUserWorkItem(new WaitCallback(ThreadProc), ti)) {    
        Console.WriteLine("Main thread does some work, then sleeps.");

        // If you comment out the Sleep, the main thread exits before
        // the ThreadPool task has a chance to run.  ThreadPool uses 
        // background threads, which do not keep the application 
        // running.  (This is a simple example of a race condition.)
        Thread.Sleep(1000);

        Console.WriteLine("Main thread exits.");
    }
    else {
        Console.WriteLine("Unable to queue ThreadPool request."); 
    }


// The thread procedure performs the independent task, in this case
// formatting and printing a very simple report.
//
static void ThreadProc(Object stateInfo) {
    TaskInfo ti = (TaskInfo) stateInfo;
    Console.WriteLine(ti.Boilerplate, ti.Value); 
}

Problem

I have two threads, one needs to poll a bunch of separate static resources looking for updates. The other one needs to get the data and store it in the database. How can thread 1 tell thread 2 that there is something to process?

Original source