Scatter/gather on sockets?

[Roy Smith]

Peter Hansen <peter at engcorp.com> wrote:
> B. Don't bother trying, because even if the MTU is large enough there is 
> absolutely no guarantee that the packet will stay intact all the way 
> through the network anyway (even if you use sendall() instead of send()).

This is true, but I'm generating the message being sent in very small 
chunks (often as small as 4 bytes at a time), and typically need to flush a 
packet out onto the network after a few dozen bytes.  Maybe at most a few 
hundred.  I don't know of any networks with MTU's smaller than that.  
Measurements show a 10-fold improvement in protocol throughput with large 
packets vs. small ones.  The only question is what's the most efficient way 
in Python to generate the large packets.

> So fixing your design not to require this appears to be the only viable 
> solution.

My design is not broken.  I'm writing code to drive a pre-existing binary 
communications protocol.  It is what it is.  The functionality I seek 
exists at the Unix system call level (writev, sendmsg), but doesn't appear 
to be exposed in the Python socket API.