add ft support for func annotation read

Author: xuantengh

Lib/test/test_free_threading/test_func_annotations.py

@@ -0,0 +1,31 @@
+import concurrent.futures
+import unittest
+from threading import Thread, Barrier
+from unittest import TestCase
+
+from test.support import threading_helper, Py_GIL_DISABLED
+
+threading_helper.requires_working_threading(module=True)
+
+
+def get_func_annotate(f, b):
+    b.wait()
+    return f.__annotation__
+
+
+@unittest.skipUnless(Py_GIL_DISABLED, "Enable only in FT build")
+class TestFTFuncAnnotations(TestCase):
+    def test_concurrent_read(self):
+        def f(x: int) -> int:
+            return x + 1
+
+        num_threads = 8
+        b = Barrier(num_threads)
+        threads = []
+
+        with concurrent.futures.ThreadPoolExecutor(max_workers=num_threads) as executor:
+            futures = {executor.submit(get_func_annotate, f, b): i for i in range(num_threads)}
+            for fut in concurrent.futures.as_completed(futures):
+                annotate = fut.result()
+                self.assertIsNotNone(annotate)
+                self.assertEqual(annotate, {'x': int, 'return': int})

Objects/funcobject.c

@@ -2,11 +2,12 @@
 /* Function object implementation */
 
 #include "Python.h"
-#include "pycore_dict.h"          // _Py_INCREF_DICT()
-#include "pycore_long.h"          // _PyLong_GetOne()
-#include "pycore_modsupport.h"    // _PyArg_NoKeywords()
-#include "pycore_object.h"        // _PyObject_GC_UNTRACK()
-#include "pycore_pyerrors.h"      // _PyErr_Occurred()
+#include "pycore_dict.h"                // _Py_INCREF_DICT()
+#include "pycore_long.h"                // _PyLong_GetOne()
+#include "pycore_modsupport.h"          // _PyArg_NoKeywords()
+#include "pycore_object.h"              // _PyObject_GC_UNTRACK()
+#include "pycore_pyerrors.h"            // _PyErr_Occurred()
+#include "pycore_critical_section.h"    // Py_BEGIN_CRITICAL_SECTION()
 
 
 static const char *
@@ -863,13 +864,16 @@ static PyObject *
 func_get_annotations(PyObject *self, void *Py_UNUSED(ignored))
 {
     PyFunctionObject *op = _PyFunction_CAST(self);
+    PyObject *d;
+    Py_BEGIN_CRITICAL_SECTION(self);
     if (op->func_annotations == NULL &&
         (op->func_annotate == NULL || !PyCallable_Check(op->func_annotate))) {
         op->func_annotations = PyDict_New();
         if (op->func_annotations == NULL)
             return NULL;
     }
-    PyObject *d = func_get_annotation_dict(op);
+    d = func_get_annotation_dict(op);
+    Py_END_CRITICAL_SECTION();
     return Py_XNewRef(d);
 }
 
@@ -887,8 +891,10 @@ func_set_annotations(PyObject *self, PyObject *value, void *Py_UNUSED(ignored))
             "__annotations__ must be set to a dict object");
         return -1;
     }
+    Py_BEGIN_CRITICAL_SECTION(self);
     Py_XSETREF(op->func_annotations, Py_XNewRef(value));
     Py_CLEAR(op->func_annotate);
+    Py_END_CRITICAL_SECTION();
     return 0;
 }