From a75cb90de2967688aac1b5b7abcddde831a6ba6f 2017-03-24 20:12:21
From: Leo Singer <leo.singer@ligo.org>
Date: 2017-03-24 20:12:21
Subject: [PATCH] Speed up shutdown by eliminating unnecessary sleeping

Eliminate an annoying split-second pause when closing a shell session
by reducing unnecessary sleeps while killing background scripts.
If there are no bacgkround scripts running, or if they shut down on
the first or second attempt, then we can eliminate some pauses.

---

diff --git a/IPython/core/magics/script.py b/IPython/core/magics/script.py
index b0532c5..2ed3112 100644
--- a/IPython/core/magics/script.py
+++ b/IPython/core/magics/script.py
@@ -245,6 +245,8 @@ class ScriptMagics(Magics):
 
     def kill_bg_processes(self):
         """Kill all BG processes which are still running."""
+        if not self.bg_processes:
+            return
         for p in self.bg_processes:
             if p.poll() is None:
                 try:
@@ -252,6 +254,9 @@ class ScriptMagics(Magics):
                 except:
                     pass
         time.sleep(0.1)
+        self._gc_bg_processes()
+        if not self.bg_processes:
+            return
         for p in self.bg_processes:
             if p.poll() is None:
                 try:
@@ -259,6 +264,9 @@ class ScriptMagics(Magics):
                 except:
                     pass
         time.sleep(0.1)
+        self._gc_bg_processes()
+        if not self.bg_processes:
+            return
         for p in self.bg_processes:
             if p.poll() is None:
                 try: