stop looking for proxy settings

docs/quickstart.rst

@@ -51,6 +51,10 @@ The :py:class:`HttpLocust <locust.core.HttpLocust>` class inherits from the
 :py:class:`Locust <locust.core.Locust>` class, and it adds a client attribute which is an instance of
 :py:class:`HttpSession <locust.clients.HttpSession>` that can be used to make HTTP requests.
 
+By default, we stop looking for proxy settings to improve performance. If you really want the test requests
+go through a HTTP proxy, you can inherit from the :py:class:`HttpLocust <locust.core.HttpLocust>` class and
+set the trust_env field to True. For further details, refer to the documentation of requests.
+
 Another way we could declare tasks, which is usually more convenient, is to use the
 ``@task`` decorator. The following code is equivalent to the above:
 

locust/core.py

@@ -187,13 +187,22 @@ class HttpLocust(Locust):
     Instance of HttpSession that is created upon instantiation of Locust. 
     The client support cookies, and therefore keeps the session between HTTP requests.
     """
+
+    trust_env = False
+    """
+    Look for proxy settings will slow down the default http client.
+    It's the default behavior of the requests library.
+    We don't need this feature most of the time, so disable it by default.
+    """
 
     def __init__(self):
         super(HttpLocust, self).__init__()
         if self.host is None:
             raise LocustError("You must specify the base host. Either in the host attribute in the Locust class, or on the command line using the --host option.")
-
-        self.client = HttpSession(base_url=self.host)
+
+        session = HttpSession(base_url=self.host)
+        session.trust_env = self.trust_env
+        self.client = session
 
 
 class TaskSetMeta(type):

locust/test/testcases.py

@@ -80,6 +80,7 @@ def no_content_length():
     r = send_file(BytesIO("This response does not have content-length in the header".encode('utf-8')),
                   add_etags=False,
                   mimetype='text/plain')
+    r.headers.remove("Content-Length")
     return r
 
 @app.errorhandler(404)