RustPython · youknowone · Jan 17, 2026 · Jan 14, 2026 · Jan 17, 2026 · Jan 17, 2026
diff --git a/Lib/contextvars.py b/Lib/contextvars.py
@@ -1,4 +1,8 @@
+import _collections_abc
 from _contextvars import Context, ContextVar, Token, copy_context
 
 
 __all__ = ('Context', 'ContextVar', 'Token', 'copy_context')
+
+
+_collections_abc.Mapping.register(Context)
diff --git a/Lib/test/test_sys.py b/Lib/test/test_sys.py
@@ -889,10 +889,11 @@ def test_sys_flags(self):
                  "dont_write_bytecode", "no_user_site", "no_site",
                  "ignore_environment", "verbose", "bytes_warning", "quiet",
                  "hash_randomization", "isolated", "dev_mode", "utf8_mode",
-                 "warn_default_encoding", "safe_path", "int_max_str_digits")
+                 "warn_default_encoding", "safe_path", "int_max_str_digits",
+                 "thread_inherit_context")
         for attr in attrs:
             self.assertTrue(hasattr(sys.flags, attr), attr)
-            attr_type = bool if attr in ("dev_mode", "safe_path") else int
+            attr_type = bool if attr in ("dev_mode", "safe_path", "thread_inherit_context") else int
             self.assertEqual(type(getattr(sys.flags, attr)), attr_type, attr)
         self.assertTrue(repr(sys.flags))
         self.assertEqual(len(sys.flags), len(attrs))

diff --git a/Lib/threading.py b/Lib/threading.py
@@ -3,7 +3,7 @@
 import os as _os
 import sys as _sys
 import _thread
-import warnings
+import _contextvars
 
 from time import monotonic as _time
 from _weakrefset import WeakSet
@@ -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
@@ -129,6 +133,7 @@ def RLock(*args, **kwargs):
 
     """
     if args or kwargs:
+        import warnings
         warnings.warn(
             'Passing arguments to RLock is deprecated and will be removed in 3.15',
             DeprecationWarning,
@@ -160,7 +165,7 @@ def __repr__(self):
         except KeyError:
             pass
         return "<%s %s.%s object owner=%r count=%d at %s>" % (
-            "locked" if self._block.locked() else "unlocked",
+            "locked" if self.locked() else "unlocked",
             self.__class__.__module__,
             self.__class__.__qualname__,
             owner,
@@ -237,6 +242,10 @@ def release(self):
     def __exit__(self, t, v, tb):
         self.release()
 
+    def locked(self):
+        """Return whether this object is locked."""
+        return self._block.locked()
+
     # Internal methods used by condition variables
 
     def _acquire_restore(self, state):
@@ -282,9 +291,10 @@ def __init__(self, lock=None):
         if lock is None:
             lock = RLock()
         self._lock = lock
-        # Export the lock's acquire() and release() methods
+        # Export the lock's acquire(), release(), and locked() methods
         self.acquire = lock.acquire
         self.release = lock.release
+        self.locked = lock.locked
         # If the lock defines _release_save() and/or _acquire_restore(),
         # these override the default implementations (which just call
         # release() and acquire() on the lock).  Ditto for _is_owned().
@@ -868,7 +878,7 @@ class Thread:
     _initialized = False
 
     def __init__(self, group=None, target=None, name=None,
-                 args=(), kwargs=None, *, daemon=None):
+                 args=(), kwargs=None, *, daemon=None, context=None):
         """This constructor should always be called with keyword arguments. Arguments are:
 
         *group* should be None; reserved for future extension when a ThreadGroup
@@ -885,6 +895,14 @@ class is implemented.
         *kwargs* is a dictionary of keyword arguments for the target
         invocation. Defaults to {}.
 
+        *context* is the contextvars.Context value to use for the thread.
+        The default value is None, which means to check
+        sys.flags.thread_inherit_context.  If that flag is true, use a copy
+        of the context of the caller.  If false, use an empty context.  To
+        explicitly start with an empty context, pass a new instance of
+        contextvars.Context().  To explicitly start with a copy of the current
+        context, pass the value from contextvars.copy_context().
+
         If a subclass overrides the constructor, it must make sure to invoke
         the base class constructor (Thread.__init__()) before doing anything
         else to the thread.
@@ -914,10 +932,11 @@ class is implemented.
             self._daemonic = daemon
         else:
             self._daemonic = current_thread().daemon
+        self._context = context
         self._ident = None
         if _HAVE_THREAD_NATIVE_ID:
             self._native_id = None
-        self._handle = _ThreadHandle()
+        self._os_thread_handle = _ThreadHandle()
         self._started = Event()
         self._initialized = True
         # Copy of sys.stderr used by self._invoke_excepthook()
@@ -932,7 +951,7 @@ def _after_fork(self, new_ident=None):
         if new_ident is not None:
             # This thread is alive.
             self._ident = new_ident
-            assert self._handle.ident == new_ident
+            assert self._os_thread_handle.ident == new_ident
             if _HAVE_THREAD_NATIVE_ID:
                 self._set_native_id()
         else:
@@ -945,7 +964,7 @@ def __repr__(self):
         status = "initial"
         if self._started.is_set():
             status = "started"
-        if self._handle.is_done():
+        if self._os_thread_handle.is_done():
             status = "stopped"
         if self._daemonic:
             status += " daemon"
@@ -971,9 +990,19 @@ def start(self):
 
         with _active_limbo_lock:
             _limbo[self] = self
+
+        if self._context is None:
+            # No context provided
+            if _sys.flags.thread_inherit_context:
+                # start with a copy of the context of the caller
+                self._context = _contextvars.copy_context()
+            else:
+                # start with an empty context
+                self._context = _contextvars.Context()
+
         try:
             # Start joinable thread
-            _start_joinable_thread(self._bootstrap, handle=self._handle,
+            _start_joinable_thread(self._bootstrap, handle=self._os_thread_handle,
                                    daemon=self.daemon)
         except Exception:
             with _active_limbo_lock:
@@ -1025,11 +1054,20 @@ def _set_ident(self):
         def _set_native_id(self):
             self._native_id = get_native_id()
 
+    def _set_os_name(self):
+        if _set_name is None or not self._name:
+            return
+        try:
+            _set_name(self._name)
+        except OSError:
+            pass
+
     def _bootstrap_inner(self):
         try:
             self._set_ident()
             if _HAVE_THREAD_NATIVE_ID:
                 self._set_native_id()
+            self._set_os_name()
             self._started.set()
             with _active_limbo_lock:
                 _active[self._ident] = self
@@ -1041,7 +1079,7 @@ def _bootstrap_inner(self):
                 _sys.setprofile(_profile_hook)
 
             try:
-                self.run()
+                self._context.run(self.run)
             except:
                 self._invoke_excepthook(self)
         finally:
@@ -1092,7 +1130,7 @@ def join(self, timeout=None):
         if timeout is not None:
             timeout = max(timeout, 0)
 
-        self._handle.join(timeout)
+        self._os_thread_handle.join(timeout)
 
     @property
     def name(self):
@@ -1109,6 +1147,8 @@ def name(self):
     def name(self, name):
         assert self._initialized, "Thread.__init__() not called"
         self._name = str(name)
+        if get_ident() == self._ident:
+            self._set_os_name()
 
     @property
     def ident(self):
@@ -1143,7 +1183,7 @@ def is_alive(self):
 
         """
         assert self._initialized, "Thread.__init__() not called"
-        return self._started.is_set() and not self._handle.is_done()
+        return self._started.is_set() and not self._os_thread_handle.is_done()
 
     @property
     def daemon(self):
@@ -1354,7 +1394,7 @@ def __init__(self):
         Thread.__init__(self, name="MainThread", daemon=False)
         self._started.set()
         self._ident = _get_main_thread_ident()
-        self._handle = _make_thread_handle(self._ident)
+        self._os_thread_handle = _make_thread_handle(self._ident)
         if _HAVE_THREAD_NATIVE_ID:
             self._set_native_id()
         with _active_limbo_lock:
@@ -1402,15 +1442,15 @@ def __init__(self):
                         daemon=_daemon_threads_allowed())
         self._started.set()
         self._set_ident()
-        self._handle = _make_thread_handle(self._ident)
+        self._os_thread_handle = _make_thread_handle(self._ident)
         if _HAVE_THREAD_NATIVE_ID:
             self._set_native_id()
         with _active_limbo_lock:
             _active[self._ident] = self
         _DeleteDummyThreadOnDel(self)
 
     def is_alive(self):
-        if not self._handle.is_done() and self._started.is_set():
+        if not self._os_thread_handle.is_done() and self._started.is_set():
             return True
         raise RuntimeError("thread is not alive")
 
@@ -1524,7 +1564,7 @@ def _shutdown():
     # dubious, but some code does it. We can't wait for it to be marked as done
     # normally - that won't happen until the interpreter is nearly dead. So
     # mark it done here.
-    if _main_thread._handle.is_done() and _is_main_interpreter():
+    if _main_thread._os_thread_handle.is_done() and _is_main_interpreter():
         # _shutdown() was already called
         return
 
@@ -1537,7 +1577,7 @@ def _shutdown():
         atexit_call()
 
     if _is_main_interpreter():
-        _main_thread._handle._set_done()
+        _main_thread._os_thread_handle._set_done()
 
     # Wait for all non-daemon threads to exit.
     _thread_shutdown()

diff --git a/crates/vm/src/stdlib/sys.rs b/crates/vm/src/stdlib/sys.rs
@@ -1301,6 +1301,8 @@ mod sys {
         safe_path: bool,
         /// -X warn_default_encoding, PYTHONWARNDEFAULTENCODING
         warn_default_encoding: u8,
+        /// -X thread_inherit_context, whether new threads inherit context from parent
+        thread_inherit_context: bool,
     }
 
     impl FlagsData {
@@ -1324,6 +1326,7 @@ mod sys {
                 int_max_str_digits: settings.int_max_str_digits,
                 safe_path: settings.safe_path,
                 warn_default_encoding: settings.warn_default_encoding as u8,
+                thread_inherit_context: settings.thread_inherit_context,
             }
         }
     }

diff --git a/crates/vm/src/vm/setting.rs b/crates/vm/src/vm/setting.rs
@@ -88,6 +88,9 @@ pub struct Settings {
     /// -X warn_default_encoding, PYTHONWARNDEFAULTENCODING
     pub warn_default_encoding: bool,
 
+    /// -X thread_inherit_context, whether new threads inherit context from parent
+    pub thread_inherit_context: bool,
+
     /// -i
     pub inspect: bool,
 
@@ -190,6 +193,7 @@ impl Default for Settings {
             isolated: false,
             dev_mode: false,
             warn_default_encoding: false,
+            thread_inherit_context: false,
             warnoptions: vec![],
             path_list: vec![],
             argv: vec![],

diff --git a/src/settings.rs b/src/settings.rs
@@ -285,6 +285,20 @@ pub fn parse_opts() -> Result<(Settings, RunMode), lexopt::Error> {
                     }
                 };
             }
+            "thread_inherit_context" => {
+                settings.thread_inherit_context = match value {
+                    Some("1") => true,
+                    Some("0") => false,
+                    _ => {
+                        error!(
+                            "Fatal Python error: config_init_thread_inherit_context: \
+                             -X thread_inherit_context=n: n is missing or invalid\n\
+                             Python runtime state: preinitialized"
+                        );
+                        std::process::exit(1);
+                    }
+                };
+            }
             _ => {}
         }
         (name, value.map(str::to_owned))
@@ -297,6 +311,20 @@ pub fn parse_opts() -> Result<(Settings, RunMode), lexopt::Error> {
     if env_bool("PYTHONNODEBUGRANGES") {
         settings.code_debug_ranges = false;
     }
+    if let Some(val) = get_env("PYTHON_THREAD_INHERIT_CONTEXT") {
+        settings.thread_inherit_context = match val.to_str() {
+            Some("1") => true,
+            Some("0") => false,
+            _ => {
+                error!(
+                    "Fatal Python error: config_init_thread_inherit_context: \
+                     PYTHON_THREAD_INHERIT_CONTEXT=N: N is missing or invalid\n\
+                     Python runtime state: preinitialized"
+                );
+                std::process::exit(1);
+            }
+        };
+    }
 
     // Parse PYTHONIOENCODING=encoding[:errors]
     if let Some(val) = get_env("PYTHONIOENCODING")