restore tornado 1.x compat
More tornado 2x
no longer call tornado's set_nonblocking function tested against an existing service that still works okay.
it's been removed
keep open file descriptors to the paths that zygote itself needs open
rewrite signal handling code in zygote
Make AFUnixSender send immediately if possible
Pass io_loop instance as **kwargs for get_application
handle initialization errors better
Invoke pre-fork initialization function.