fix(tracing): keep numpy loaded during module cleanup

ddtrace/bootstrap/cloning.py

@@ -76,6 +76,7 @@ def drop(module_name: str) -> None:
             "attr",
             "google",
             "google.protobuf",  # the upb backend in >= 4.21 does not like being unloaded
+            "numpy",  # its C extension cannot be re-initialized in >= 2.4 (numpy/numpy#29030)
             "wrapt",
             "bytecode",  # needed by before-fork hooks
             "pathlib",  # used in singledispatch

releasenotes/notes/fix-keep-numpy-loaded-545940f0c2b806e7.yaml

@@ -0,0 +1,6 @@
+---
+fixes:
+  - |
+    tracing: This fix resolves an ``ImportError: cannot load module more than once per process``
+    that could occur when ``numpy`` (2.4 or later) was imported both before and after
+    ``ddtrace.auto``.

tests/internal/test_auto.py

@@ -129,6 +129,27 @@ class B(A):
     assert b
 
 
+@pytest.mark.subprocess(env=dict(DD_UNLOAD_MODULES_FROM_SITECUSTOMIZE="true"))
+def test_numpy_not_unloaded():
+    import sys
+
+    import ddtrace  # noqa: F401
+
+    # numpy >= 2.4 refuses to re-initialize its C extension, so if cleanup drops
+    # it and user code re-imports, the second import raises ImportError. Keep it
+    # loaded across the cleanup. Regression test for issue #18276.
+    have_numpy = True
+    try:
+        import numpy  # noqa: F401
+    except ImportError:
+        have_numpy = False
+
+    import ddtrace.auto  # noqa: F401
+
+    if have_numpy:
+        assert "numpy" in sys.modules
+
+
 @pytest.mark.subprocess(env=dict(DD_UNLOAD_MODULES_FROM_SITECUSTOMIZE="true"))
 def test_yaml_not_unloaded():
     # Regression test for APMS-20000. The module cleanup used to drop and force a