"Action" if IOLoop blocked more than n seconds

[rschildmeijer]

facebook/tornado detects (with pythons signal module) if the ioloop is blocked more than n seconds. Its possible to supply a callback (action) that is called if the ioloop is blocked for more than n seconds. (hint set_blocking_signal_threshold & set_blocking_log_threshold log_stack in ioloop.py, https://github.com/facebook/tornado/blob/master/tornado/ioloop.py)