fix comments and move thread name reset in test

Author: jadonduff

Lib/test/test_threading.py

@@ -2281,9 +2281,6 @@ def test__all__(self):
     @unittest.skipUnless(hasattr(_thread, 'set_name'), "missing _thread.set_name")
     @unittest.skipUnless(hasattr(_thread, '_get_name'), "missing _thread._get_name")
     def test_set_name(self):
-        # Ensure main thread name is restored after test
-        self.addCleanup(_thread.set_name, _thread._get_name())
-
         # set_name() limit in bytes
         truncate = getattr(_thread, "_NAME_MAXLEN", None)
         limit = truncate or 100
@@ -2359,6 +2356,9 @@ def work():
                 if '\0' in expected:
                     expected = expected.split('\0', 1)[0]
 
+            # Ensure main thread name is restored after test
+            self.addCleanup(_thread.set_name, _thread._get_name())
+
             with self.subTest(name=name, expected=expected, thread="main"):
                 _thread.set_name(name)
                 self.assertEqual(_thread._get_name(), expected)

Modules/_threadmodule.c

@@ -2523,8 +2523,8 @@ _thread__get_name_impl(PyObject *module)
     }
 
 #ifdef __sun
-    // Decode Solaris/Illumos (e.g. OpenIndiana) thread names as ASCII
-    // since OpenIndiana only supports ASCII names.
+    // gh-138004: Decode Solaris/Illumos (e.g. OpenIndiana) thread names
+    //  from ASCII, since OpenIndiana only supports ASCII names.
     return PyUnicode_DecodeASCII(name, strlen(name), "surrogateescape");
 #else
     return PyUnicode_DecodeFSDefault(name);
@@ -2563,7 +2563,7 @@ _thread_set_name_impl(PyObject *module, PyObject *name_obj)
 {
 #ifndef MS_WINDOWS
 #ifdef __sun
-    // Encode Solaris/Illumos thread names as ASCII
+    // gh-138004: Encode Solaris/Illumos thread names to ASCII,
     // since OpenIndiana does not support non-ASCII names.
     const char *encoding = "ascii";
 #else