Thanks all for your reply. The main reason that I liked to use sockets was the drop of performance on Windows when using open3 to schedule a lot of processes (whith each having a pipe reader thread on stdout and stderr). The scheduler seems to hang on either launching new processes, or on the threaded-pipe-reader.

The advantage of using sockets is that I can use select (also on Windows. select on pipes is not possible, and I did not like to work with Win32 WaitForMultipleObjects). I'm about finished with a prototype (not using open3 anymore), which seems to look promising (actually, I was able to get about 100% load on my dual six-core HT system).