RustPython · youknowone · Dec 30, 2025 · Dec 30, 2025 · Dec 30, 2025 · Dec 30, 2025
diff --git a/Lib/multiprocessing/connection.py b/Lib/multiprocessing/connection.py
@@ -74,7 +74,7 @@ def arbitrary_address(family):
     if family == 'AF_INET':
         return ('localhost', 0)
     elif family == 'AF_UNIX':
-        return tempfile.mktemp(prefix='listener-', dir=util.get_temp_dir())
+        return tempfile.mktemp(prefix='sock-', dir=util.get_temp_dir())
     elif family == 'AF_PIPE':
         return tempfile.mktemp(prefix=r'\\.\pipe\pyc-%d-%d-' %
                                (os.getpid(), next(_mmap_counter)), dir="")

diff --git a/Lib/multiprocessing/resource_tracker.py b/Lib/multiprocessing/resource_tracker.py
@@ -15,11 +15,15 @@
 # this resource tracker process, "killall python" would probably leave unlinked
 # resources.
 
+import base64
 import os
 import signal
 import sys
 import threading
 import warnings
+from collections import deque
+
+import json
 
 from . import spawn
 from . import util
@@ -66,6 +70,14 @@ def __init__(self):
         self._fd = None
         self._pid = None
         self._exitcode = None
+        self._reentrant_messages = deque()
+
+        # True to use colon-separated lines, rather than JSON lines,
+        # for internal communication. (Mainly for testing).
+        # Filenames not supported by the simple format will always be sent
+        # using JSON.
+        # The reader should understand all formats.
+        self._use_simple_format = True
 
     def _reentrant_call_error(self):
         # gh-109629: this happens if an explicit call to the ResourceTracker
@@ -102,7 +114,7 @@ def _stop_locked(
         # This shouldn't happen (it might when called by a finalizer)
         # so we check for it anyway.
         if self._lock._recursion_count() > 1:
-            return self._reentrant_call_error()
+            raise self._reentrant_call_error()
         if self._fd is None:
             # not running
             return
@@ -113,7 +125,12 @@ def _stop_locked(
         close(self._fd)
         self._fd = None
 
-        _, status = waitpid(self._pid, 0)
+        try:
+            _, status = waitpid(self._pid, 0)
+        except ChildProcessError:
+            self._pid = None
+            self._exitcode = None
+            return
 
         self._pid = None
 
@@ -132,76 +149,119 @@ def ensure_running(self):
 
         This can be run from any process.  Usually a child process will use
         the resource created by its parent.'''
+        return self._ensure_running_and_write()
+
+    def _teardown_dead_process(self):
+        os.close(self._fd)
+
+        # Clean-up to avoid dangling processes.
+        try:
+            # _pid can be None if this process is a child from another
+            # python process, which has started the resource_tracker.
+            if self._pid is not None:
+                os.waitpid(self._pid, 0)
+        except ChildProcessError:
+            # The resource_tracker has already been terminated.
+            pass
+        self._fd = None
+        self._pid = None
+        self._exitcode = None
+
+        warnings.warn('resource_tracker: process died unexpectedly, '
+                      'relaunching.  Some resources might leak.')
+
+    def _launch(self):
+        fds_to_pass = []
+        try:
+            fds_to_pass.append(sys.stderr.fileno())
+        except Exception:
+            pass
+        r, w = os.pipe()
+        try:
+            fds_to_pass.append(r)
+            # process will out live us, so no need to wait on pid
+            exe = spawn.get_executable()
+            args = [
+                exe,
+                *util._args_from_interpreter_flags(),
+                '-c',
+                f'from multiprocessing.resource_tracker import main;main({r})',
+            ]
+            # bpo-33613: Register a signal mask that will block the signals.
+            # This signal mask will be inherited by the child that is going
+            # to be spawned and will protect the child from a race condition
+            # that can make the child die before it registers signal handlers
+            # for SIGINT and SIGTERM. The mask is unregistered after spawning
+            # the child.
+            prev_sigmask = None
+            try:
+                if _HAVE_SIGMASK:
+                    prev_sigmask = signal.pthread_sigmask(signal.SIG_BLOCK, _IGNORED_SIGNALS)
+                pid = util.spawnv_passfds(exe, args, fds_to_pass)
+            finally:
+                if prev_sigmask is not None:
+                    signal.pthread_sigmask(signal.SIG_SETMASK, prev_sigmask)
+        except:
+            os.close(w)
+            raise
+        else:
+            self._fd = w
+            self._pid = pid
+        finally:
+            os.close(r)
+
+    def _make_probe_message(self):
+        """Return a probe message."""
+        if self._use_simple_format:
+            return b'PROBE:0:noop\n'
+        return (
+            json.dumps(
+                {"cmd": "PROBE", "rtype": "noop"},
+                ensure_ascii=True,
+                separators=(",", ":"),
+            )
+            + "\n"
+        ).encode("ascii")
+
+    def _ensure_running_and_write(self, msg=None):
         with self._lock:
             if self._lock._recursion_count() > 1:
                 # The code below is certainly not reentrant-safe, so bail out
-                return self._reentrant_call_error()
+                if msg is None:
+                    raise self._reentrant_call_error()
+                return self._reentrant_messages.append(msg)
+
             if self._fd is not None:
                 # resource tracker was launched before, is it still running?
-                if self._check_alive():
-                    # => still alive
-                    return
-                # => dead, launch it again
-                os.close(self._fd)
-
-                # Clean-up to avoid dangling processes.
+                if msg is None:
+                    to_send = self._make_probe_message()
+                else:
+                    to_send = msg
                 try:
-                    # _pid can be None if this process is a child from another
-                    # python process, which has started the resource_tracker.
-                    if self._pid is not None:
-                        os.waitpid(self._pid, 0)
-                except ChildProcessError:
-                    # The resource_tracker has already been terminated.
-                    pass
-                self._fd = None
-                self._pid = None
-                self._exitcode = None
+                    self._write(to_send)
+                except OSError:
+                    self._teardown_dead_process()
+                    self._launch()
 
-                warnings.warn('resource_tracker: process died unexpectedly, '
-                              'relaunching.  Some resources might leak.')
+                msg = None  # message was sent in probe
+            else:
+                self._launch()
 
-            fds_to_pass = []
-            try:
-                fds_to_pass.append(sys.stderr.fileno())
-            except Exception:
-                pass
-            cmd = 'from multiprocessing.resource_tracker import main;main(%d)'
-            r, w = os.pipe()
+        while True:
             try:
-                fds_to_pass.append(r)
-                # process will out live us, so no need to wait on pid
-                exe = spawn.get_executable()
-                args = [exe] + util._args_from_interpreter_flags()
-                args += ['-c', cmd % r]
-                # bpo-33613: Register a signal mask that will block the signals.
-                # This signal mask will be inherited by the child that is going
-                # to be spawned and will protect the child from a race condition
-                # that can make the child die before it registers signal handlers
-                # for SIGINT and SIGTERM. The mask is unregistered after spawning
-                # the child.
-                prev_sigmask = None
-                try:
-                    if _HAVE_SIGMASK:
-                        prev_sigmask = signal.pthread_sigmask(signal.SIG_BLOCK, _IGNORED_SIGNALS)
-                    pid = util.spawnv_passfds(exe, args, fds_to_pass)
-                finally:
-                    if prev_sigmask is not None:
-                        signal.pthread_sigmask(signal.SIG_SETMASK, prev_sigmask)
-            except:
-                os.close(w)
-                raise
-            else:
-                self._fd = w
-                self._pid = pid
-            finally:
-                os.close(r)
+                reentrant_msg = self._reentrant_messages.popleft()
+            except IndexError:
+                break
+            self._write(reentrant_msg)
+        if msg is not None:
+            self._write(msg)
 
     def _check_alive(self):
         '''Check that the pipe has not been closed by sending a probe.'''
         try:
             # We cannot use send here as it calls ensure_running, creating
             # a cycle.
-            os.write(self._fd, b'PROBE:0:noop\n')
+            os.write(self._fd, self._make_probe_message())
         except OSError:
             return False
         else:
@@ -215,27 +275,42 @@ def unregister(self, name, rtype):
         '''Unregister name of resource with resource tracker.'''
         self._send('UNREGISTER', name, rtype)
 
-    def _send(self, cmd, name, rtype):
-        try:
-            self.ensure_running()
-        except ReentrantCallError:
-            # The code below might or might not work, depending on whether
-            # the resource tracker was already running and still alive.
-            # Better warn the user.
-            # (XXX is warnings.warn itself reentrant-safe? :-)
-            warnings.warn(
-                f"ResourceTracker called reentrantly for resource cleanup, "
-                f"which is unsupported. "
-                f"The {rtype} object {name!r} might leak.")
-        msg = '{0}:{1}:{2}\n'.format(cmd, name, rtype).encode('ascii')
-        if len(msg) > 512:
-            # posix guarantees that writes to a pipe of less than PIPE_BUF
-            # bytes are atomic, and that PIPE_BUF >= 512
-            raise ValueError('msg too long')
+    def _write(self, msg):
         nbytes = os.write(self._fd, msg)
-        assert nbytes == len(msg), "nbytes {0:n} but len(msg) {1:n}".format(
-            nbytes, len(msg))
+        assert nbytes == len(msg), f"{nbytes=} != {len(msg)=}"
 
+    def _send(self, cmd, name, rtype):
+        if self._use_simple_format and '\n' not in name:
+            msg = f"{cmd}:{name}:{rtype}\n".encode("ascii")
+            if len(msg) > 512:
+                # posix guarantees that writes to a pipe of less than PIPE_BUF
+                # bytes are atomic, and that PIPE_BUF >= 512
+                raise ValueError('msg too long')
+            self._ensure_running_and_write(msg)
+            return
+
+        # POSIX guarantees that writes to a pipe of less than PIPE_BUF (512 on Linux)
+        # bytes are atomic. Therefore, we want the message to be shorter than 512 bytes.
+        # POSIX shm_open() and sem_open() require the name, including its leading slash,
+        # to be at most NAME_MAX bytes (255 on Linux)
+        # With json.dump(..., ensure_ascii=True) every non-ASCII byte becomes a 6-char
+        # escape like \uDC80.
+        # As we want the overall message to be kept atomic and therefore smaller than 512,
+        # we encode encode the raw name bytes with URL-safe Base64 - so a 255 long name
+        # will not exceed 340 bytes.
+        b = name.encode('utf-8', 'surrogateescape')
+        if len(b) > 255:
+            raise ValueError('shared memory name too long (max 255 bytes)')
+        b64 = base64.urlsafe_b64encode(b).decode('ascii')
+
+        payload = {"cmd": cmd, "rtype": rtype, "base64_name": b64}
+        msg = (json.dumps(payload, ensure_ascii=True, separators=(",", ":")) + "\n").encode("ascii")
+
+        # The entire JSON message is guaranteed < PIPE_BUF (512 bytes) by construction.
+        assert len(msg) <= 512, f"internal error: message too long ({len(msg)} bytes)"
+        assert msg.startswith(b'{')
+
+        self._ensure_running_and_write(msg)
 
 _resource_tracker = ResourceTracker()
 ensure_running = _resource_tracker.ensure_running
@@ -244,6 +319,30 @@ def _send(self, cmd, name, rtype):
 getfd = _resource_tracker.getfd
 
 
+def _decode_message(line):
+    if line.startswith(b'{'):
+        try:
+            obj = json.loads(line.decode('ascii'))
+        except Exception as e:
+            raise ValueError("malformed resource_tracker message: %r" % (line,)) from e
+
+        cmd = obj["cmd"]
+        rtype = obj["rtype"]
+        b64  = obj.get("base64_name", "")
+
+        if not isinstance(cmd, str) or not isinstance(rtype, str) or not isinstance(b64, str):
+            raise ValueError("malformed resource_tracker fields: %r" % (obj,))
+
+        try:
+            name = base64.urlsafe_b64decode(b64).decode('utf-8', 'surrogateescape')
+        except ValueError as e:
+            raise ValueError("malformed resource_tracker base64_name: %r" % (b64,)) from e
+    else:
+        cmd, rest = line.strip().decode('ascii').split(':', maxsplit=1)
+        name, rtype = rest.rsplit(':', maxsplit=1)
+    return cmd, rtype, name
+
+
 def main(fd):
     '''Run resource tracker.'''
     # protect the process from ^C and "killall python" etc
@@ -266,7 +365,7 @@ def main(fd):
         with open(fd, 'rb') as f:
             for line in f:
                 try:
-                    cmd, name, rtype = line.strip().decode('ascii').split(':')
+                    cmd, rtype, name = _decode_message(line)
                     cleanup_func = _CLEANUP_FUNCS.get(rtype, None)
                     if cleanup_func is None:
                         raise ValueError(