8dspaces · September 11, 2016 03:54 · Dec 8, 2014 · Dec 8, 2014 · Dec 7, 2014
diff --git a/async_flask.py b/async_flask.py
@@ -12,8 +12,7 @@
 # need to patch sockets to make requests async
 monkey.patch_all()
 
-# TODO experiment with different chunk sizes
-CHUNK_SIZE = 1024  # bytes
+CHUNK_SIZE = 1024*1024  # bytes
 
 app = Flask(__name__)  # pylint: disable=invalid-name
 app.debug = True

diff --git a/async_flask.py b/async_flask.py
@@ -34,6 +34,7 @@ def seattle(requests_counter=[0]):  # pylint: disable=dangerous-default-value
 
     def generator():
         "streaming generator logging the end of request processing"
+        yield ''  # to make greenlet switch
         for data in rsp.iter_content(CHUNK_SIZE):
             yield data
         app.logger.debug('finished %d', request_num)

diff --git a/async_flask.py b/async_flask.py
@@ -0,0 +1,53 @@
+"""Asynchronous requests in Flask with gevent"""
+
+from time import time
+
+from flask import Flask, Response
+
+from gevent.pywsgi import WSGIServer
+from gevent import monkey
+
+import requests
+
+# need to patch sockets to make requests async
+monkey.patch_all()
+
+# TODO experiment with different chunk sizes
+CHUNK_SIZE = 1024  # bytes
+
+app = Flask(__name__)  # pylint: disable=invalid-name
+app.debug = True
+
+
+@app.route('/Seattle.jpg')
+def seattle(requests_counter=[0]):  # pylint: disable=dangerous-default-value
+    """Asynchronous non-blocking streaming of relatively large (14.5MB) JPG
+    of Seattle from wikimedia commons.
+    """
+    requests_counter[0] += 1
+    request_num = requests_counter[0]
+    url = 'http://upload.wikimedia.org/wikipedia/commons/3/39/Seattle_3.jpg'
+
+    app.logger.debug('started %d', request_num)
+
+    rsp = requests.get(url, stream=True)
+
+    def generator():
+        "streaming generator logging the end of request processing"
+        for data in rsp.iter_content(CHUNK_SIZE):
+            yield data
+        app.logger.debug('finished %d', request_num)
+
+    return Response(generator(), mimetype='image/jpeg')
+
+
+def main():
+    "Start gevent WSGI server"
+    # use gevent WSGI server instead of the Flask
+    http = WSGIServer(('', 5000), app.wsgi_app)
+    # TODO gracefully handle shutdown
+    http.serve_forever()
+
+
+if __name__ == '__main__':
+    main()