cherry-pick from @minrk work on sharing context by default

jupyter@4cdbf54

jupyter_client/multikernelmanager.py

@@ -76,6 +76,11 @@ def _create_kernel_manager_factory(self):
  kernel_manager_ctor = import_item(self.kernel_manager_class)
 
  def create_kernel_manager(*args, **kwargs):
+ if self.shared_context:
+ if self.context.closed:
+ # recreate context if closed
+ self.context = self._context_default()
+ kwargs.setdefault("context", self.context)
  km = kernel_manager_ctor(*args, **kwargs)
 
  if km.cache_ports:
@@ -104,10 +109,28 @@ def _find_available_port(self, ip):
 
  return port
 
+ shared_context = Bool(
+ True,
+ config=True,
+ help="Share a single zmq.Context to talk to all my kernels",
+ )
+
+ _created_context = Bool(False)
+
  context = Instance('zmq.Context')
+
+ @default("context")
  def _context_default(self):
+ self._created_context = True
  return zmq.Context()
 
+ def __del__(self):
+ if self._created_context and self.context and not self.context.closed:
+ if self.log:
+ self.log.debug("Destroying zmq context for %s", self)
+ self.context.destroy()
+ super().__del__()
+
  connection_dir = Unicode('')
 
  _kernels = Dict()