We have a service running on Tornado, it is written asynchronously. I suspect that somewhere in the code there is a blocking call that hurts performance.
Is there a way in Tornado to find this code section / function call? 
Or can I find code that holds the IOLoop longer than X ms?
Thanks
Alex
In Python 3+ and Tornado 5+, set the environment variable PYTHONASYNCIODEBUG=1. In older versions of either Tornado or Python, call IOLoop.current().set_blocking_log_threshold(0.5).
Either way, this will cause a message to be logged whenever a call blocks for more than half a second.
How can I find a blocking call inside Tornado webserver?