Issue #21905: Avoid RuntimeError in pickle.whichmodule() when sys.modules is mutated while iterating.
Patch by Olivier Grisel.
diff --git a/Lib/pickle.py b/Lib/pickle.py
index 3fc2596..663773f 100644
--- a/Lib/pickle.py
+++ b/Lib/pickle.py
@@ -280,7 +280,9 @@
module_name = getattr(obj, '__module__', None)
if module_name is not None:
return module_name
- for module_name, module in sys.modules.items():
+ # Protect the iteration by using a list copy of sys.modules against dynamic
+ # modules that trigger imports of other modules upon calls to getattr.
+ for module_name, module in list(sys.modules.items()):
if module_name == '__main__' or module is None:
continue
try:
diff --git a/Misc/ACKS b/Misc/ACKS
index c91d643..3095047 100644
--- a/Misc/ACKS
+++ b/Misc/ACKS
@@ -494,6 +494,7 @@
Grant Griffin
Andrea Griffini
Duncan Grisby
+Olivier Grisel
Fabian Groffen
Eric Groo
Dag Gruneau
diff --git a/Misc/NEWS b/Misc/NEWS
index 9915e4e..6112a00 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -22,6 +22,9 @@
Library
-------
+- Issue #21905: Avoid RuntimeError in pickle.whichmodule() when sys.modules
+ is mutated while iterating. Patch by Olivier Grisel.
+
- Issue #22219: The zipfile module CLI now adds entries for directories
(including empty directories) in ZIP file.