Revert "Changes necessary to get async kernel startup working"

This reverts commit 5103959.
Plan is to introduce parallel start_kernel_async methods on
KernelManager and MultiKernelManager for now.

Author: kevin-bates

jupyter_client/manager.py

@@ -13,7 +13,7 @@
 import time
 
 import zmq
-from tornado import gen
+
 from ipython_genutils.importstring import import_item
 from .localinterfaces import is_local_ip, local_ips
 from traitlets import (
@@ -205,7 +205,6 @@ def _close_control_socket(self):
         self._control_socket.close()
         self._control_socket = None
 
-    @gen.coroutine
     def start_kernel(self, **kw):
         """Starts a kernel on this host in a separate process.
 
@@ -247,7 +246,8 @@ def start_kernel(self, **kw):
 
         # launch the kernel subprocess
         self.log.debug("Starting kernel: %s", kernel_cmd)
-        self.kernel = yield gen.maybe_future(self._launch_kernel(kernel_cmd, env=env, **kw))
+        self.kernel = self._launch_kernel(kernel_cmd, env=env,
+                                    **kw)
         self.start_restarter()
         self._connect_control_socket()
 
@@ -324,7 +324,6 @@ def shutdown_kernel(self, now=False, restart=False):
 
         self.cleanup(connection_file=not restart)
 
-    @gen.coroutine
     def restart_kernel(self, now=False, newports=False, **kw):
         """Restarts a kernel with the arguments that were used to launch it.
 
@@ -362,7 +361,7 @@ def restart_kernel(self, now=False, newports=False, **kw):
 
             # Start new kernel.
             self._launch_args.update(kw)
-            yield gen.maybe_future(self.start_kernel(**self._launch_args))
+            self.start_kernel(**self._launch_args)
 
     @property
     def has_kernel(self):

jupyter_client/multikernelmanager.py

@@ -7,9 +7,9 @@
 
 import os
 import uuid
+
 import zmq
 
-from tornado import gen
 from traitlets.config.configurable import LoggingConfigurable
 from ipython_genutils.importstring import import_item
 from traitlets import (
@@ -82,7 +82,6 @@ def __len__(self):
     def __contains__(self, kernel_id):
         return kernel_id in self._kernels
 
-    @gen.coroutine
     def start_kernel(self, kernel_name=None, **kwargs):
         """Start a new kernel.
 
@@ -108,9 +107,9 @@ def start_kernel(self, kernel_name=None, **kwargs):
                     parent=self, log=self.log, kernel_name=kernel_name,
                     **constructor_kwargs
         )
-        yield gen.maybe_future(km.start_kernel(**kwargs))
+        km.start_kernel(**kwargs)
         self._kernels[kernel_id] = km
-        raise gen.Return(kernel_id)
+        return kernel_id
 
     @kernel_method
     def shutdown_kernel(self, kernel_id, now=False, restart=False):
@@ -187,25 +186,15 @@ def signal_kernel(self, kernel_id, signum):
         """
         self.log.info("Signaled Kernel %s with %s" % (kernel_id, signum))
 
-    @gen.coroutine
+    @kernel_method
     def restart_kernel(self, kernel_id, now=False):
         """Restart a kernel by its uuid, keeping the same ports.
 
         Parameters
         ==========
         kernel_id : uuid
-            The id of the kernel to restart.
-
-        now : bool, optional
-            If True, the kernel is forcefully restarted *immediately*, without
-            having a chance to do any cleanup action.  Otherwise the kernel is
-            given 1s to clean up before a forceful restart is issued.
-
-            In all cases the kernel is restarted, the only difference is whether
-            it is given a chance to perform a clean shutdown or not.
+            The id of the kernel to interrupt.
         """
-        km = self.get_kernel(kernel_id)
-        yield gen.maybe_future(km.restart_kernel(now))
         self.log.info("Kernel restarted: %s" % kernel_id)
 
     @kernel_method