C# Socket BeginReceive / EndReceive capturing multiple messages

Question

Problem:

When I do something like this:

for (int i = 0; i < 100; i++)
{
    SendMessage( sometSocket, i.ToString());
    Thread.Sleep(250); // works          


        

Answer 1

This is expected behaviour. A TCP socket represents a linear stream of bytes, not a sequence of well-delimited “packets”. You must not assume that the data you receive is chunked the same way it was when it was sent.

Notice that this has two consequences:

1. Two messages may get merged into a single callback call. (You noticed this one.)
2. A single message may get split up (at any point) into two separate callback calls.

Your code must be written to handle both of these cases, otherwise it has a bug.