HTTP/RPC tracing library for Tornado
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Tornado Tracing

This library instruments HTTP calls in a Tornado application and provides visualizations to find where your app is spending its time and identify opportunities for parallelism. It uses the Appstats module from the Google App Engine SDK.

Tornado Tracing is licensed under the Apache License, Version 2.0 (


You will need:


In most cases, you can simply use/subclass RecordingRequestHandler and AsyncHTTPClient from tornado_tracing.recording instead of the corresponding Tornado classes. These classes do nothing special unless the --enable_appstats flag is passed.

At startup, you must call tornado_tracing.config.setup_memcache() to tell the system where your memcache server is running. You can also use tornado_tracing.config.set_options() to set certain other options, such as KEY_PREFIX if multiple applications are sharing a memcache server and you want to keep the data separate.

Finally, add tornado_tracing.config.get_urlspec() to your Application's list of handlers. This is where the trace output will be visible. Note that the UI does not have to be served from the same process where the data is generated, as long as they're all using the same memcache.