fix(internal): ignore non-standard modules [backport #7732 to 1.20] (#8469)

Backport of #7732 to 1.20

When mapping imported modules to their origin, we handle non-standard
objects to ensure that we do not raise an exception if we find a module
that either has no origin, or that cannot be referenced weakly. We
expect these cases to be of no importance to the tracking process, as
these modules are unlikely to provide useful information via the Python
runtime.

Fixes #7730.

## Checklist

- [x] Change(s) are motivated and described in the PR description.
- [x] Testing strategy is described if automated tests are not included
in the PR.
- [x] Risk is outlined (performance impact, potential for breakage,
maintainability, etc).
- [x] Change is maintainable (easy to change, telemetry, documentation).
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`changelog/no-changelog`.
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corp docs](https://github.com/DataDog/documentation/)).
- [x] Backport labels are set (if
[applicable](https://ddtrace.readthedocs.io/en/latest/contributing.html#backporting))

## Reviewer Checklist

- [x] Title is accurate.
- [x] No unnecessary changes are introduced.
- [x] Description motivates each change.
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[API](https://ddtrace.readthedocs.io/en/stable/versioning.html#interfaces)
changes unless absolutely necessary.
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implications of this PR as reported in the benchmarks PR comment.
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Author: P403n1x87

ddtrace/internal/module.py

@@ -250,16 +250,35 @@ def __init__(self):
     @property
     def _origin_map(self):
         # type: () -> wvdict[str, ModuleType]
+        def modules_with_origin(modules):
+            result = wvdict()
+
+            for m in modules:
+                module_origin = origin(m)
+                if module_origin is None:
+                    continue
+
+                try:
+                    result[str(module_origin)] = m
+                except TypeError:
+                    # This can happen if the module is a special object that
+                    # does not allow for weak references. Quite likely this is
+                    # an object created by a native extension. We make the
+                    # assumption that this module does not contain valuable
+                    # information that can be used at the Python runtime level.
+                    pass
+
+            return result
+
         if self._om is None:
             try:
-                self._om = wvdict({origin(module): module for module in sys.modules.values()})
+                self._om = modules_with_origin(sys.modules.values())
             except RuntimeError:
                 # The state of sys.modules might have been mutated by another
                 # thread. We try to build the full mapping at the next occasion.
                 # For now we take the more expensive route of building a list of
                 # the current values, which might be incomplete.
-                return wvdict({origin(module): module for module in list(sys.modules.values())})
-
+                return modules_with_origin(list(sys.modules.values()))
         return self._om
 
     def _add_to_meta_path(self):

releasenotes/notes/fix-ignore-non-standard-modules-318862ee5c68be0f.yaml

@@ -0,0 +1,5 @@
+---
+fixes:
+  - |
+    dynamic instrumentation: Fix an issue that caused the instrumented
+    application to fail to start if a non-standard module was imported.

tests/internal/test_module.py

@@ -400,3 +400,17 @@ def lazy_import(name):
         lazy.__spec__
     except AttributeError:
         pass
+
+
+@pytest.mark.subprocess(ddtrace_run=True)
+def test_module_watchdog_weakref():
+    """Check that we can ignore entries in sys.modules that cannot be weakref'ed."""
+    import sys
+
+    sys.modules["bogus"] = str.__init__  # Cannot create weak ref to method_descriptor
+
+    from ddtrace.internal.module import ModuleWatchdog
+
+    instance = ModuleWatchdog._instance
+    instance._om = None
+    assert ModuleWatchdog._instance._origin_map