tests/tornado: enhance test_concurrent_requests

This tries to enhance test_concurrent_requests by waiting until all responses
have completed. There's still a default timeout set by tornado testing
framework (5 seconds) that can be exceeded, but that should be more solid in
practice than the previous 0.5 seconds delay that was used.

We also make sure threads worked fine by joining them rather than setting them
as daemons.

This also makes sure we use `tornado.gen.sleep` function when available.

Fixes #914

Author: jd

tests/contrib/tornado/test_safety.py

@@ -17,29 +17,35 @@ class TestAsyncConcurrency(TornadoTestCase):
     """
     @gen_test
     def test_concurrent_requests(self):
+        REQUESTS_NUMBER = 25
+        responses = []
+
         # the application must handle concurrent calls
         def make_requests():
             # use a blocking HTTP client (we're in another thread)
             http_client = httpclient.HTTPClient()
             url = self.get_url('/nested/')
             response = http_client.fetch(url)
+            responses.append(response)
             assert 200 == response.code
             assert 'OK' == response.body.decode('utf-8')
             # freeing file descriptors
             http_client.close()
 
         # blocking call executed in different threads
-        threads = [threading.Thread(target=make_requests) for _ in range(25)]
+        threads = [threading.Thread(target=make_requests) for _ in range(REQUESTS_NUMBER)]
         for t in threads:
-            t.daemon = True
             t.start()
 
-        # wait for the execution; assuming this time as a timeout
-        yield web.compat.sleep(0.5)
+        while len(responses) < REQUESTS_NUMBER:
+            yield web.compat.sleep(0.001)
+
+        for t in threads:
+            t.join()
 
         # the trace is created
         traces = self.tracer.writer.pop_traces()
-        assert 25 == len(traces)
+        assert REQUESTS_NUMBER == len(traces)
         assert 2 == len(traces[0])
 
 

tests/contrib/tornado/web/compat.py

@@ -1,4 +1,5 @@
 from tornado.concurrent import Future
+import tornado.gen
 from tornado.ioloop import IOLoop
 
 
@@ -24,12 +25,16 @@ def __init__(self, *args, **kwargs):
             super(ThreadPoolExecutor, self).__init__()
 
 
-def sleep(duration):
-    """
-    Compatibility helper that return a Future() that can be yielded.
-    This is used because Tornado 4.0 doesn't have a ``gen.sleep()``
-    function, that we require to test the ``TracerStackContext``.
-    """
-    f = Future()
-    IOLoop.current().call_later(duration, lambda: f.set_result(None))
-    return f
+if hasattr(tornado.gen, 'sleep'):
+    sleep = tornado.gen.sleep
+else:
+    # Tornado <= 4.0
+    def sleep(duration):
+        """
+        Compatibility helper that return a Future() that can be yielded.
+        This is used because Tornado 4.0 doesn't have a ``gen.sleep()``
+        function, that we require to test the ``TracerStackContext``.
+        """
+        f = Future()
+        IOLoop.current().call_later(duration, lambda: f.set_result(None))
+        return f