High CPU load using WCF streaming

Question

I've been doing a lot of research on this issue but unfortunately I wasn't able to find a solution. My problem is that I am experiencing a quite high CPU load even on powerful machines when using WCF (NetTcpBinding, Streamed) - to be more specific, my i5 860 has a load of 20-40 percent when handling 20 client threads. When it comes to deploying a real service (and not a testing project) and there's around 50 real clients sending small data packages every second (around 20kb per transfer) the CPU load is already at 80-90 percent. In the end there should be 200+ clients but I can't imagine how this should work with such CPU loads...

For testing purposes I have set up a small project with just a simple client and server based on WCF streamed transfer using NetTcpBinding. There's already a lot of 'desperation code' in it, because I have tried to make it work... for my testing I used a 200MB file that's being sent to the WCF service 20 times.

Here's the contract:

[ServiceContract(Namespace = "WCFStreamTest.WCFService")]
public interface IStreamContract
{
    [OperationContract(Name = "ReceiveStream")]
    StreamMessage ReceiveStream(StreamMessage msg);

    [OperationContract(Name = "SendStream")]
    StreamMessage SendStream(StreamMessage msg);
}

The StreamMessage class used in here is just a MessageContract containing a string header and a Stream object.

The server code looks as follows:

[ServiceBehavior(IncludeExceptionDetailInFaults = false, InstanceContextMode = InstanceContextMode.PerCall, ConcurrencyMode = ConcurrencyMode.Multiple, UseSynchronizationContext = true, MaxItemsInObjectGraph = int.MaxValue)]
public class StreamService : IStreamContract
{
    public StreamMessage ReceiveStream(StreamMessage msg)
    {
        if (File.Exists(msg.Parameters))
            return new StreamMessage() { Parameters = msg.Parameters, DataStream = new System.IO.FileStream(msg.Parameters, System.IO.FileMode.Open, System.IO.FileAccess.Read) };

        return new StreamMessage();
    }

    public StreamMessage SendStream(StreamMessage msg)
    {
        if (msg.Parameters.Trim().Length > 0)
        {
            int bufferSize = 8096 * 4;
            byte[] buffer = new byte[bufferSize];
            int bytes = 0;

            while ((bytes = msg.DataStream.Read(buffer, 0, bufferSize)) > 0)
            {
                byte b = buffer[0];
                b = (byte)(b + 1);
            }
        }

        return new StreamMessage();
    }
}

The test project just uses the SendStream method for testing - and that method just reads the data stream and does nothing else.

At this point I think I'll just save your time reading and don't post the full code in here. Maybe a download link to the demo project will be sufficient? (To make it work there is one line in the client's Program.cs that's object to be changed: FileInfo fi = new FileInfo(@"<<<>>>");)

WCFStreamTest Project

I'd be really happy about any idea on how to lower CPU usage... thanks in advance for any help and tips...

Hi, how you managed to resolve your issue, also experiencing the same thing? — Donald N. Mafa

Abhinav Abhinav · Accepted Answer · 2014-02-04T06:52:30

Can you try to make the thread sleep in while loop, and see how it goes.

while ((bytes = msg.DataStream.Read(buffer, 0, bufferSize)) > 0)
{
    byte b = buffer[0];
    b = (byte)(b + 1);
    Thread.Sleep(100);
}

If it is a video streaming service you might have to tweak the sleep interval.

High CPU load using WCF streaming

1 Answers