gh-59705: Add _thread.set_name() function

Lib/test/test_threading.py

@@ -2103,6 +2103,61 @@ def test__all__(self):
         support.check__all__(self, threading, ('threading', '_thread'),
                              extra=extra, not_exported=not_exported)
 
+    def test_set_name(self):
+        try:
+            get_name = _thread._get_name
+            _thread.set_name
+        except AttributeError:
+            self.skipTest("need thread._get_name() and thread.set_name()")
+
+        def work():
+            nonlocal work_name
+            work_name = get_name()
+
+        # name not too long to fit into Linux 15 bytes limit
+        name = "CustomName"
+        tests = [(name, name)]
+
+        # Test non-ASCII short name
+        name = "namé€"
+        try:
+            os.fsencode(name)
+        except UnicodeEncodeError:
+            # name cannot be encoded to the filesystem encoding
+            pass
+        else:
+            tests.append((name, name))
+
+        if sys.platform == "linux":
+            # On Linux, set_name() truncates the name to 15 bytes.
+
+            # Test ASCII name
+            name = "x" * 100
+            tests.append((name, name[:15]))
+
+            # Test non-ASCII name
+            name = "x" * 14 + "é€"
+            try:
+                encoded = os.fsencode(name)
+            except UnicodeEncodeError:
+                # name cannot be encoded to the filesystem encoding
+                pass
+            else:
+                expected = os.fsdecode(encoded[:15])
+                tests.append((name, expected))
+        else:
+            # Test long name
+            name = "x" * 100
+            tests.append((name, name))
+
+        for name, expected in tests:
+            with self.subTest(name=name, expected=expected):
+                work_name = None
+                thread = threading.Thread(target=work, name=name)
+                thread.start()
+                thread.join()
+                self.assertEqual(work_name, expected)
+
 
 class InterruptMainTests(unittest.TestCase):
     def check_interrupt_main_with_signal_handler(self, signum):

Lib/threading.py

@@ -48,6 +48,10 @@
     __all__.append('get_native_id')
 except AttributeError:
     _HAVE_THREAD_NATIVE_ID = False
+try:
+    _set_name = _thread.set_name
+except AttributeError:
+    _set_name = None
 ThreadError = _thread.error
 try:
     _CRLock = _thread.RLock
@@ -1027,6 +1031,8 @@ def _bootstrap_inner(self):
             self._set_ident()
             if _HAVE_THREAD_NATIVE_ID:
                 self._set_native_id()
+            if _set_name is not None and self._name:
+                _set_name(self._name)
             self._started.set()
             with _active_limbo_lock:
                 _active[self._ident] = self

Misc/NEWS.d/next/Library/2024-11-27-17-04-38.gh-issue-59705.sAGyvs.rst

@@ -0,0 +1,2 @@
+On Linux, :class:`threading.Thread` now sets the thread name to the
+operating system. Patch by Victor Stinner.

Modules/_threadmodule.c

@@ -17,6 +17,8 @@
 #  include <signal.h>             // SIGINT
 #endif
 
+#include "clinic/_threadmodule.c.h"
+
 // ThreadError is just an alias to PyExc_RuntimeError
 #define ThreadError PyExc_RuntimeError
 
@@ -44,6 +46,13 @@ get_thread_state(PyObject *module)
     return (thread_module_state *)state;
 }
 
+
+/*[clinic input]
+module _thread
+[clinic start generated code]*/
+/*[clinic end generated code: output=da39a3ee5e6b4b0d input=be8dbe5cc4b16df7]*/
+
+
 // _ThreadHandle type
 
 // Handles state transitions according to the following diagram:
@@ -2354,6 +2363,74 @@ PyDoc_STRVAR(thread__get_main_thread_ident_doc,
 Internal only. Return a non-zero integer that uniquely identifies the main thread\n\
 of the main interpreter.");
 
+
+#ifdef HAVE_PTHREAD_GETNAME_NP
+/*[clinic input]
+_thread._get_name
+
+Get the name of the current thread.
+[clinic start generated code]*/
+
+static PyObject *
+_thread__get_name_impl(PyObject *module)
+/*[clinic end generated code: output=20026e7ee3da3dd7 input=35cec676833d04c8]*/
+{
+    char name[17];
+    size_t size = Py_ARRAY_LENGTH(name) - 1;
+    pthread_t thread = pthread_self();
+    int rc = pthread_getname_np(thread, name, size);
+    if (rc) {
+        errno = rc;
+        return PyErr_SetFromErrno(PyExc_OSError);
+    }
+
+    name[size] = 0;
+    return PyUnicode_DecodeFSDefault(name);
+}
+#endif  // HAVE_PTHREAD_GETNAME_NP
+
+
+#ifdef HAVE_PTHREAD_SETNAME_NP
+/*[clinic input]
+_thread.set_name
+
+    name as name_obj: object(converter="PyUnicode_FSConverter")
+
+Set the name of the current thread.
+[clinic start generated code]*/
+
+static PyObject *
+_thread_set_name_impl(PyObject *module, PyObject *name_obj)
+/*[clinic end generated code: output=402b0c68e0c0daed input=a0459bd64f771808]*/
+{
+    const char *name = PyBytes_AS_STRING(name_obj);
+#ifdef __APPLE__
+    int rc = pthread_setname_np(name);
+#else
+
+#if defined(__linux__)
+    // Truncate to 16 bytes including the NUL byte
+    char buffer[16];
+    size_t len = strlen(name);
+    if (len > 15) {
+        memcpy(buffer, name, 15);
+        buffer[15] = 0;
+        name = buffer;
+    }
+#endif
+
+    pthread_t thread = pthread_self();
+    int rc = pthread_setname_np(thread, name);
+#endif
+    if (rc) {
+        errno = rc;
+        return PyErr_SetFromErrno(PyExc_OSError);
+    }
+    Py_RETURN_NONE;
+}
+#endif  // HAVE_PTHREAD_SETNAME_NP
+
+
 static PyMethodDef thread_methods[] = {
     {"start_new_thread",        (PyCFunction)thread_PyThread_start_new_thread,
      METH_VARARGS, start_new_thread_doc},
@@ -2393,6 +2470,8 @@ static PyMethodDef thread_methods[] = {
      METH_O, thread__make_thread_handle_doc},
     {"_get_main_thread_ident", thread__get_main_thread_ident,
      METH_NOARGS, thread__get_main_thread_ident_doc},
+    _THREAD_SET_NAME_METHODDEF
+    _THREAD__GET_NAME_METHODDEF
     {NULL,                      NULL}           /* sentinel */
 };
 

configure.ac

@@ -5105,8 +5105,10 @@ AC_CHECK_FUNCS([ \
   mknod mknodat mktime mmap mremap nice openat opendir pathconf pause pipe \
   pipe2 plock poll posix_fadvise posix_fallocate posix_openpt posix_spawn posix_spawnp \
   posix_spawn_file_actions_addclosefrom_np \
-  pread preadv preadv2 process_vm_readv pthread_cond_timedwait_relative_np pthread_condattr_setclock pthread_init \
-  pthread_kill ptsname ptsname_r pwrite pwritev pwritev2 readlink readlinkat readv realpath renameat \
+  pread preadv preadv2 process_vm_readv \
+  pthread_cond_timedwait_relative_np pthread_condattr_setclock pthread_init \
+  pthread_kill pthread_getname_np pthread_setname_np \
+  ptsname ptsname_r pwrite pwritev pwritev2 readlink readlinkat readv realpath renameat \
   rtpSpawn sched_get_priority_max sched_rr_get_interval sched_setaffinity \
   sched_setparam sched_setscheduler sem_clockwait sem_getvalue sem_open \
   sem_timedwait sem_unlink sendfile setegid seteuid setgid sethostname \

pyconfig.h.in

@@ -981,6 +981,9 @@
 /* Define to 1 if you have the `pthread_getcpuclockid' function. */
 #undef HAVE_PTHREAD_GETCPUCLOCKID
 
+/* Define to 1 if you have the `pthread_getname_np' function. */
+#undef HAVE_PTHREAD_GETNAME_NP
+
 /* Define to 1 if you have the <pthread.h> header file. */
 #undef HAVE_PTHREAD_H
 
@@ -990,6 +993,9 @@
 /* Define to 1 if you have the `pthread_kill' function. */
 #undef HAVE_PTHREAD_KILL
 
+/* Define to 1 if you have the `pthread_setname_np' function. */
+#undef HAVE_PTHREAD_SETNAME_NP
+
 /* Define to 1 if you have the `pthread_sigmask' function. */
 #undef HAVE_PTHREAD_SIGMASK