"Matplotlib support failed" when importing matplotlib subpackages (PY-29260)

Sometimes activation function can be called, when matplotlib module isn't fully imported. Do not remove activation function until the module is imported properly.

python/helpers/pydev/_pydev_bundle/pydev_import_hook.py

@@ -1,4 +1,3 @@
-
 import sys
 import traceback
 from types import ModuleType
@@ -16,19 +15,23 @@ class ImportHookManager(ModuleType):
     def do_import(self, name, *args, **kwargs):
         activate_func = None
         if name in self._modules_to_patch:
-            activate_func = self._modules_to_patch.pop(name)
+            activate_func = self._modules_to_patch[name]
 
         module = self._system_import(name, *args, **kwargs)
         try:
             if activate_func:
-                activate_func() #call activate function
+                succeeded = activate_func()
+                if succeeded and name in self._modules_to_patch:
+                    # Remove if only it was executed correctly
+                    self._modules_to_patch.pop(name)
         except:
             sys.stderr.write("Matplotlib support failed\n")
             traceback.print_exc()
         return module
 
+
 if sys.version_info[0] >= 3:
-    import builtins # py3
+    import builtins  # py3
 else:
     import __builtin__ as builtins
 

python/helpers/pydev/pydev_ipython/matplotlibtools.py

@@ -90,6 +90,9 @@ def activate_matplotlib(enable_gui_function):
     enable_gui_function - Function which enables gui, should be run in the main thread.
     """
     matplotlib = sys.modules['matplotlib']
+    if not hasattr(matplotlib, 'rcParams'):
+        # matplotlib module wasn't fully imported, try later
+        return False
     gui, backend = find_gui_and_backend()
     is_interactive = is_interactive_backend(backend)
     if is_interactive:
@@ -103,6 +106,7 @@ def activate_matplotlib(enable_gui_function):
         matplotlib.interactive(False)
     patch_use(enable_gui_function)
     patch_is_interactive()
+    return True
 
 
 def flag_calls(func):
@@ -139,6 +143,7 @@ def activate_pylab():
     # We need to detect at runtime whether show() is called by the user.
     # For this, we wrap it into a decorator which adds a 'called' flag.
     pylab.draw_if_interactive = flag_calls(pylab.draw_if_interactive)
+    return True
 
 
 def activate_pyplot():
@@ -147,3 +152,4 @@ def activate_pyplot():
     # We need to detect at runtime whether show() is called by the user.
     # For this, we wrap it into a decorator which adds a 'called' flag.
     pyplot.draw_if_interactive = flag_calls(pyplot.draw_if_interactive)
+    return True