fix: cleanup_loaded_modules: dont clean up modules that have not finished loading [backport 3.16] (#14840) (#14906)

Author: juanjux

ddtrace/bootstrap/sitecustomize.py

@@ -45,6 +45,20 @@
 def cleanup_loaded_modules():
     def drop(module_name):
         # type: (str) -> None
+        module = sys.modules.get(module_name)
+        # Don't delete modules that are currently being imported (they might be None or incomplete)
+        # or that don't exist. This can happen when pytest's assertion rewriter is importing modules
+        # that themselves import ddtrace.auto, which triggers this cleanup during the import process.
+        if module is None:
+            return
+        # Skip modules that don't have a __spec__ attribute yet (still being imported)
+        if not hasattr(module, "__spec__"):
+            return
+        # Check if the module is currently being initialized
+        # During import, __spec__._initializing is True
+        spec = getattr(module, "__spec__", None)
+        if spec is not None and getattr(spec, "_initializing", False):
+            return
         del sys.modules[module_name]
 
     MODULES_REQUIRING_CLEANUP = ("gevent",)

releasenotes/notes/pytest-ddtrace-auto-e6c09074a4b0af3d.yaml

@@ -0,0 +1,4 @@
+---
+fixes:
+  - |
+    Fix some modules being unloaded too soon when using pytest + ddtrace + gevent.