test.py

from tornado import gen, httpclient, ioloop, stack_context

io_loop = ioloop.IOLoop.instance()
client = httpclient.AsyncHTTPClient(io_loop=io_loop)

@gen.engine
def go_for_it():
    c = 0

    while True:
        r = yield gen.Task(fetch)

        c += 1

        if c == 1000:
            import pdb; pdb.set_trace()

        if c % 100 == 0:
            print '%s...' % c

@gen.engine
def fetch(callback):
    #response = yield gen.Task(client.fetch, 'http://localhost:5000/')
    yield gen.Task(io_loop.add_callback)
    callback(None)

io_loop.add_callback(go_for_it)
io_loop.start()