Sleep in async application, without blocking event loop

Question

I have a problem with one my async tests: tornado seems not to be up and running (I get 599s), even though it is started as a fixture. I would like to verify that it is indeed running, by doing the following:

1. Start the test
2. Before the requests are actually sent to tornado, I would like my code to "sleep" for a long time so that I can manually check with the browser that tornado is indeed running.

How can I tell python to sleep without blocking the async loop? If I do time.sleep, the whole process (and thus the loop) is not responsive for the duration of the sleep.

Answer 1

Both of your questions are answered in Tornado's FAQ:

http://www.tornadoweb.org/en/latest/faq.html

Use yield gen.sleep(1) to wait 1 second while letting other tasks run on the event loop, or use IOLoop.current().add_timeout(1, callback) to run a callback one second later.

Don't use your browser to verify that your application handles multiple requests concurrently: the browser itself may not allow concurrent requests. Use curl instead.