Proof of concept multithreaded du -s command written in go.

make

bin/mdu DIRECTORY_ROOT

Perhaps surprisingly, this is not an IO-bound operation. Here's a non-scientific comparison with the bsd du command on a directory with ~450,000 files (run on a quadcore Macbook Pro):

$ time du -s .
137308480   .

real    0m24.239s
user    0m0.377s
sys 0m20.132s

$ time multithread_du/bin/mdu .
137308480   .

real    0m6.008s
user    0m2.559s
sys 0m27.026s