Avoid zombie processes in case of using LocalProcessSpawner

jupyterhub/proxy.py

@@ -722,6 +722,7 @@ class ConfigurableHTTPProxy(Proxy):
         def _check_process():
             status = self.proxy_process.poll()
             if status is not None:
+                with self.proxy_process:
                     e = RuntimeError("Proxy failed to start with exit code %i" % status)
                     raise e from None
 

jupyterhub/spawner.py

@@ -1542,6 +1542,9 @@ class LocalProcessSpawner(Spawner):
         if self.proc is not None:
             status = self.proc.poll()
             if status is not None:
+                # handle SIGCHILD to avoid zombie processes
+                # and also close stdout/stderr file descriptors
+                with self.proc:
                     # clear state if the process is done
                     self.clear_state()
             return status