Is there a better way to wait for queued threads?

Is there a better way to wait for queued threads before execute another process?

Currently I'm doing:

this.workerLocker = new object(); // Global variable
this.RunningWorkers = arrayStrings.Length; // Global variable

// Initiate process

foreach (string someString in arrayStrings)
{
     ThreadPool.QueueUserWorkItem(this.DoSomething, someString);
     Thread.Sleep(100);
}

// Waiting execution for all queued threads
lock (this.workerLocker)  // Global variable (object)
{
     while (this.RunningWorkers > 0)
     {
          Monitor.Wait(this.workerLocker);
     }
}

// Do anything else    
Console.WriteLine("END");

// Method DoSomething() definition
public void DoSomething(object data)
{
    // Do a slow process...
    .
    .
    .

    lock (this.workerLocker)
    {
        this.RunningWorkers--;
        Monitor.Pulse(this.workerLocker);
    }
}

c# multithreading queue

Edit Report

You likely want to take a look at AutoResetEvent and ManualResetEvent.

These are meant for exactly this situation (waiting for a ThreadPool thread to finish, prior to doing "something").

You'd do something like this:

static void Main(string[] args)
{
    List<ManualResetEvent> resetEvents = new List<ManualResetEvent>();
    foreach (var x in Enumerable.Range(1, WORKER_COUNT))
    {
        ManualResetEvent resetEvent = new ManualResetEvent();
        ThreadPool.QueueUserWorkItem(DoSomething, resetEvent);
        resetEvents.Add(resetEvent);
    }

    // wait for all ManualResetEvents
    WaitHandle.WaitAll(resetEvents.ToArray()); // You probably want to use an array instead of a List, a list was just easier for the example :-)
}

public static void DoSomething(object data)
{
    ManualResetEvent resetEvent = data as ManualResetEvent;

    // Do something

    resetEvent.Set();
}

Edit: Forgot to mention you can wait for a single thread, any thread and so forth as well. Also depending on your situation, AutoResetEvent can simplify things a bit, since it (as the name implies) can signal events automatically :-)

answered 2009-06-25T20:50:21.627

Is there a better way to wait for queued threads?

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