test_threading main name fixed, minor changes, news

Author: jadonduff

Lib/test/test_threading.py

@@ -2281,6 +2281,9 @@ 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

Misc/NEWS.d/next/Core_and_Builtins/2025-08-21-06-31-42.gh-issue-138004.FH2Hre.rst

@@ -1 +1 @@
-_thread.set_name() now retries with an ASCII fallback if pthread_setname_np() rejects UTF-8 names on some POSIX-compliant platforms.
+On Solaris/Illumos platforms, thread names are now encoded as ASCII to avoid errors on systems (e.g. OpenIndiana) that don't support non-ASCII names.

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 with "replace" to avoid decoding errors.
-    return PyUnicode_DecodeASCII(name, strlen(name), "replace");
+    // Decode Solaris/Illumos (e.g. OpenIndiana) thread names as ASCII since OpenIndiana only supports ASCII names.
+    return PyUnicode_DecodeASCII(name, strlen(name), "surrogateescape");
 #else
     return PyUnicode_DecodeFSDefault(name);
 #endif
@@ -2562,7 +2562,7 @@ _thread_set_name_impl(PyObject *module, PyObject *name_obj)
 {
 #ifndef MS_WINDOWS
 #ifdef __sun
-    // Decode Solaris/Illumos (e.g. OpenIndiana) thread names as ASCII to avoid decoding errors.
+    // Encode Solaris/Illumos thread names as ASCII since OpenIndiana does not support non-ASCII names
     const char *encoding = "ascii";
 #else
     // Encode the thread name to the filesystem encoding using the "replace"