773-sigill-introspection

https://github.com/benoitc/gunicorn/issues/773

This feature is intended to help analyse the state of gunicorn processes in a given point of time. This can come handy when dealing with performance issues.

A new signal handler for SIGILL would be introduced which triggers the status dump. When the signal is received workers dump their current requests with stack traces to the /tmp dir. If the signal is sent to the master it will broadcast it to its workers.
Berkerpeksag, I do understand your concern regarding making greenlet a required dependency and I agree that this is a real issue. I'll try to move the logic that writes out the thread information from base to its subclasses and then only async would depend on greenlet. What do you think?