Minor improvements to the parallel computing stuff.

* Made various user messages better.
* Added a longer (4s) paused before ipcluster exits.

IPython/kernel/clientconnector.py

@@ -275,19 +275,26 b' class AsyncClientConnector(object):'
 
         d = self._try_to_connect(furl_file, delay, max_tries, attempt=0)
         d.addCallback(_wrap_remote_reference)
+        d.addErrback(self._handle_error, furl_file)
         return d
 
+    def _handle_error(self, f, furl_file):
+        raise ClientConnectorError('Could not connect to the controller '
+            'using the FURL file. This usually means that i) the controller '
+            'was not started or ii) a firewall was blocking the client from '
+            'connecting to the controller: %s' % furl_file)
+
     @inlineCallbacks
     def _try_to_connect(self, furl_or_file, delay, max_tries, attempt):
         """Try to connect to the controller with retry logic."""
         if attempt < max_tries:
-            log.msg("Connecting to controller [%r]: %s" % \
-                (attempt, furl_or_file))
+            log.msg("Connecting [%r]" % attempt)
             try:
                 self.furl = find_furl(furl_or_file)
                 # Uncomment this to see the FURL being tried.
                 # log.msg("FURL: %s" % self.furl)
                 rr = yield self.get_reference(self.furl)
+                log.msg("Connected: %s" % furl_or_file)
             except:
                 if attempt==max_tries-1:
                     # This will propagate the exception all the way to the top

IPython/kernel/ipclusterapp.py

@@ -243,7 +243,7 b' class IPClusterApp(ApplicationWithClusterDir):'
                 full_path = os.path.join(path, f)
                 if os.path.isdir(full_path) and f.startswith('cluster_'):
                     profile = full_path.split('_')[-1]
-                    start_cmd = '"ipcluster start -n 4 -p %s"' % profile
+                    start_cmd = 'ipcluster start -p %s -n 4' % profile
                     print start_cmd + " ==> " + full_path
 
     def pre_construct(self):
@@ -362,7 +362,7 b' class IPClusterApp(ApplicationWithClusterDir):'
             d= self.stop_engines()
             d2 = self.stop_controller()
             # Wait a few seconds to let things shut down.
-            reactor.callLater(3.0, reactor.stop)
+            reactor.callLater(4.0, reactor.stop)
 
     def sigint_handler(self, signum, frame):
         self.stop_launchers()

IPython/kernel/multiengine.py

@@ -262,9 +262,8 b' class MultiEngine(ControllerAdapterBase):'
         elif targets == 'all':
             eList = self.engines.values()
             if len(eList) == 0:
-                msg = """There are no engines registered.
-                     Check the logs in ~/.ipython/log if you think there should have been."""
-                raise error.NoEnginesRegistered(msg)
+                raise error.NoEnginesRegistered("There are no engines registered. "
+                    "Check the logs if you think there should have been.")
             else:
                 return eList
         else: