I use

        auto pipes = pipeProcess( cmd, Redirect.stdout | Redirect.stderr );

to redirect stdout of the newly created subprocess via pipes to a file. The redirect itself happens in a newly created thread (because I need to wait for the subprocess to finish to take the exact elapsed time) doing basically:

        pipes.stdout.byChunk( 1024 * 1024 ).copy( cof.lockingTextWriter() );

This happens to use much of my CPU time (~25%). I wonder if there is no faster way to do this.
I use this method because I want to be platform independent.

Thomas

I found out that the redirect was not responsible for the CPU time, it was some other code part which was responsible for it and totally unrelated to the redirect.

I also saw that a redirect in my case is much simpler by using spawnProcess:

auto logFile = File("errors.log", "w");
auto pid = spawnProcess(["dmd", "myprog.d"],
                        std.stdio.stdin,
                        std.stdio.stdout,
                        logFile);