lots of futex_wait calls

[skunkwerk]

I've got a python program written for the django web framework that
starts about 100 threads.  When I start the server, it sometimes eats
up 100% of the CPU for a good minute or so... though none of the
threads are CPU-intensive

doing a strace on the program, i found lots of calls like this:

select(5, [4], [], [], {1, 0}) = 0 (Timeout)
futex(0x86a3ce0, FUTEX_WAIT, 0, NULL) = 0

i've read the man page for futex... but is this normal?

thanks