I'm currently programming a client application and I'm wondering whether I should use the Socket class' ReceiveAsync or BeginReceive method. I have been using the latter so far, however, I found that it seems to stress the CPU quite a bit. Here is what my receive loop basically looks like:
private void socket_ReceiveCallback(IAsyncResult result_)
{
// does nothing else at the moment
socket.EndReceive(result_);
byte[] buffer = (byte[])result_.AsyncState;
// receive new packet
byte[] newBuffer = new byte[1024];
socket.BeginReceive(newBuffer, 0, newBuffer.Length, SocketFlags.None,
socket_ReceiveFallback, newBuffer);
}
Now I've been wondering if I am doing something wrong here, since other applications that communicate hardly stress the CPU at all. And also I'm wondering if I would be better off with using SocketAsyncEventArgs and ReceiveAsync.
So here are my questions:
Why is my loop stressing the CPU so much?
Should I use SocketAsyncEventArgs and ReceiveAsync instead of BeginReceive?
Best Answer
I have been benchmarking synchronous vs. asynchronous socket on on a localhost loopback connection. My results were that the asynchronous version was about 30% slower. That was surprising to me considering that async IO is all the rage now. It didn't matter how many threads I used. I could use 128 threads and still synchronous IO was faster.
The reason for that is, I believe, that async IO requires more allocations and more kernel mode transitions.
So you could just switch to synchronous IO, if you don't expect hundreds of simultaneous connections.