Fail on start if any child threads can't start.

CHANGES.rst

@@ -11,6 +11,7 @@ develop
   `python_platform_implementation` environment marker.
 * Moved repository to https://github.com/django-ddp/django-ddp (new
   Github organisation).
+* Fail on start if any child threads can't start (eg: port in use).
 * Add missing versions and dates to the change log, and note on Semantic 
   Versioning.
 * Back to universal wheels, thanks to PEP-0496 environment markers.

dddp/main.py

@@ -207,7 +207,12 @@ class DDPLauncher(object):
         self.print('=> Started PostgresGreenlet.')
         for server in self.servers:
             thread = gevent.spawn(server.serve_forever)
+            gevent.sleep()  # yield to thread in case it can't start
             self.threads.append(thread)
+            if thread.dead:
+                # thread died, stop everything and re-raise the exception.
+                self.stop()
+                thread.get()
             if isinstance(server, geventwebsocket.WebSocketServer):
                 self.print(
                     '=> App running at: %s://%s:%d/' % (