Deadlock in InternalUploadFile

[katsela]

I went through SftpClient briefly and I noticed that the reset event is only set when s.StatusCode == StatusCodes.Ok

_sftpSession.RequestWrite(handle, offset, buffer, 0, bytesRead, null, s =>
                        {
                            if (s.StatusCode == StatusCodes.Ok)
                            {
                                Interlocked.Decrement(ref expectedResponses);
                                responseReceivedWaitHandle.Set();

                                //  Call callback to report number of bytes written
                                if (uploadCallback != null)
                                {
                                    //  Execute callback on different thread
                                    ThreadAbstraction.ExecuteThread(() => uploadCallback(writtenBytes));
                                }
                            }
                        });

which means that
once loop reaches

//  Wait for expectedResponses to change 
_sftpSession.WaitOnHandle(responseReceivedWaitHandle, _operationTimeout);

and status code for all write requests != StatusCodes.Ok the loop will hang

This is not just observation I've seen it happen many times, this results in thread starvation for the host application eventually.