matplotlib
diff --git a/‎lib/matplotlib/pyplot.py
Copy file name to clipboardExpand all lines: lib/matplotlib/pyplot.py
+15-5Lines changed: 15 additions & 5 deletions b/‎lib/matplotlib/pyplot.py
Copy file name to clipboardExpand all lines: lib/matplotlib/pyplot.py
+15-5Lines changed: 15 additions & 5 deletions
@@ -332,11 +332,21 @@ def draw_if_interactive():
 
 
 def _warn_if_gui_out_of_main_thread():
-    # This compares native thread ids because even if python-level Thread
-    # objects match, the underlying OS thread (which is what really matters)
-    # may be different on Python implementations with green threads.
-    if (_get_required_interactive_framework(_get_backend_mod()) and
-            threading.get_native_id() != threading.main_thread().native_id):
+    warn = False
+    if _get_required_interactive_framework(_get_backend_mod()):
+        if hasattr(threading, 'get_native_id'):
+            # This compares native thread ids because even if Python-level
+            # Thread objects match, the underlying OS thread (which is what
+            # really matters) may be different on Python implementations with
+            # green threads.
+            if threading.get_native_id() != threading.main_thread().native_id:
+                warn = True
+        else:
+            # Fall back to Python-level Thread if native IDs are unavailable,
+            # mainly for PyPy.
+            if threading.current_thread() is not threading.main_thread():
+                warn = True
+    if warn:
         _api.warn_external(
             "Starting a Matplotlib GUI outside of the main thread will likely "
             "fail.")