WCF NetTcpBinding Buffered vs Streamed performance problems

Question

I wrote a WCF service that should transform any size of files, using the Streamed TransferMode in NetTcpBinding, and System.IO.Stream object.

When running performance test, i found significant performance problem. Then I decided to test it with Buffered TransferMode and saw that performance is two times faster!

Because my service should transfer big files, i just can't stay in Buffered TransferMode because of memory management overhead on big files at the server and client side together.

Why is Streamed TransferMode slower than the Buffered TransferMode? What can i do to make Stremed performance better?

Answer 1

How big are the chunks you are streaming? You might experiment with varying chunk sizes, and varying strategies.
Also, consider using Asynch IO to fill the buffers to be transferred, or after transfer.

What I mean is, if your streaming algorithm is serial, like so:

1. Fill a chunk
2. send the chunk
3. get confirmation
4. more chunks?  Go to step 1

...then you have a lot of unnecessary delay. If you can fill chunks and send chunks in parallel, then you'll be able to reduce waiting. Async IO is one way to do that. You would have two parallel workstreams happening. Conceptually, it might look like this:

Filling Chunks                              Sending Chunks
  1. call BeginRead                           1. get next chunk
  2. wait for callback                        2. send it
  3. more to read? yes -> go to step 1        3. await confirmation
  4. done                                     4. more? go to step 1

But using Async IO, these could actually be driven by the same thread.

Keep this in mind:

Did you read MS's article on the topic of large data streaming in WCF?