tornado 5 support (#1918)

 tornado 5 support by keeping track of the periodic callbacks

gunicorn/workers/gtornado.py

@@ -19,9 +19,13 @@
 from gunicorn import __version__ as gversion
 
 
-# `io_loop` arguments to many Tornado functions have been removed in Tornado 5.0
-# <http://www.tornadoweb.org/en/stable/releases/v5.0.0.html#backwards-compatibility-notes>
-IOLOOP_PARAMETER_REMOVED = tornado.version_info >= (5, 0, 0)
+# Tornado 5.0 updated its IOLoop, and the `io_loop` arguments to many
+# Tornado functions have been removed in Tornado 5.0. Also, they no
+# longer store PeriodCallbacks in ioloop._callbacks. Instead we store
+# them on our side, and use stop() on them when stopping the worker.
+# See https://www.tornadoweb.org/en/stable/releases/v5.0.0.html#backwards-compatibility-notes
+# for more details.
+TORNADO5 = tornado.version_info >= (5, 0, 0)
 
 
 class TornadoWorker(Worker):
@@ -66,8 +70,13 @@ def heartbeat(self):
                         pass
                 self.server_alive = False
             else:
-                if not self.ioloop._callbacks:
+                if TORNADO5:
+                    for callback in self.callbacks:
+                        callback.stop()
                     self.ioloop.stop()
+                else:
+                    if not self.ioloop._callbacks:
+                        self.ioloop.stop()
 
     def init_process(self):
         # IOLoop cannot survive a fork or be shared across processes
@@ -81,9 +90,13 @@ def run(self):
         self.ioloop = IOLoop.instance()
         self.alive = True
         self.server_alive = False
-        if IOLOOP_PARAMETER_REMOVED:
-            PeriodicCallback(self.watchdog, 1000).start()
-            PeriodicCallback(self.heartbeat, 1000).start()
+
+        if TORNADO5:
+            self.callbacks = []
+            self.callbacks.append(PeriodicCallback(self.watchdog, 1000))
+            self.callbacks.append(PeriodicCallback(self.heartbeat, 1000))
+            for callback in self.callbacks:
+                callback.start()
         else:
             PeriodicCallback(self.watchdog, 1000, io_loop=self.ioloop).start()
             PeriodicCallback(self.heartbeat, 1000, io_loop=self.ioloop).start()
@@ -127,13 +140,13 @@ def on_close(instance, server_conn):
             # options
             del _ssl_opt["do_handshake_on_connect"]
             del _ssl_opt["suppress_ragged_eofs"]
-            if IOLOOP_PARAMETER_REMOVED:
+            if TORNADO5:
                 server = server_class(app, ssl_options=_ssl_opt)
             else:
                 server = server_class(app, io_loop=self.ioloop,
                                       ssl_options=_ssl_opt)
         else:
-            if IOLOOP_PARAMETER_REMOVED:
+            if TORNADO5:
                 server = server_class(app)
             else:
                 server = server_class(app, io_loop=self.ioloop)