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Recommendations for executing .NET HttpWebRequests in parallel in ASP.NET

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失恋的感觉
失恋的感觉 2021-01-13 04:37

I have an ASP.NET MVC web application that makes REST style web service calls to other servers. I have a scenario where I am making two HttpWebRequest calls to two separate

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  • 醉话见心
    醉话见心 (楼主)
    2021-01-13 04:50

    One of the answers to Multithreading WebRequests, a good and stable approach? : CSharp uses a ManualResetEvent event = new ManualResetEvent(), a reference counter equaling the number of in flight requests and Interlocked.Decrement to control the event.Set(). The main thread then waits by calling event.WaitOne().

    However, WaitHandles - Auto/ManualResetEvent and Mutex mentions that ManualResetEvent "can be significantly slower than using the various Monitor methods" like Wait, Pulse and PulseAll.

    I ended up basing my code off of this Noah Blumenthal blog post: Run generic tasks async (fluent-ly). I did make two changes: implement IDisposable and call .Close() on the ManualResetEvent and switch from using a lock() to Interlocked .Increment() and .Decrement().

    public class AsyncQueueManager : IDisposable {
    private readonly ManualResetEvent waitHandle = new ManualResetEvent(true);
    private int count = 0;

    public AsyncQueueManager Queue(Action action) {
        Interlocked.Increment(ref count);
        waitHandle.Reset();
        Action actionWrapper = CreateActionWrapper(action);
        WaitCallback waitCallback = new WaitCallback(actionWrapper);
        ThreadPool.QueueUserWorkItem(waitCallback);
        return this;
    }

    private Action CreateActionWrapper(Action action) {
        Action actionWrapper = (object state) =>
        {
            try {
                action(state);
            } catch (Exception ex) {
                // log
            } finally {
                if (Interlocked.Decrement(ref count) == 0) {
                    waitHandle.Set();
                }
            }
        };
        return actionWrapper;
    }

    public void Wait() {
        waitHandle.WaitOne();
    }
    public void Wait(TimeSpan timeout) {
        waitHandle.WaitOne(timeout);
    }

    public void Dispose() {
        waitHandle.Close();
    }
}

    
    
             
    
                                                        
    
            
            
    
              
                
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