gh-96471: Add multiprocessing queue shutdown

Doc/library/multiprocessing.rst

@@ -845,7 +845,8 @@ For an example of the usage of queues for interprocess communication see
       free slot was available within that time.  Otherwise (*block* is
       ``False``), put an item on the queue if a free slot is immediately
       available, else raise the :exc:`queue.Full` exception (*timeout* is
-      ignored in that case).
+      ignored in that case).  Raises :exc:`ShutDown` if the queue has been shut
+      down.
 
       .. versionchanged:: 3.8
          If the queue is closed, :exc:`ValueError` is raised instead of
@@ -863,7 +864,9 @@ For an example of the usage of queues for interprocess communication see
       it blocks at most *timeout* seconds and raises the :exc:`queue.Empty`
       exception if no item was available within that time.  Otherwise (block is
       ``False``), return an item if one is immediately available, else raise the
-      :exc:`queue.Empty` exception (*timeout* is ignored in that case).
+      :exc:`queue.Empty` exception (*timeout* is ignored in that case).  Raises
+      :exc:`queue.ShutDown` if the queue has been shut down and is empty, or if
+      the queue has been shut down immediately.
 
       .. versionchanged:: 3.8
          If the queue is closed, :exc:`ValueError` is raised instead of
@@ -873,6 +876,19 @@ For an example of the usage of queues for interprocess communication see
 
       Equivalent to ``get(False)``.
 
+   .. method:: shutdown(immediate=False)
+
+      Shut-down the queue, making queue gets and puts raise
+      :exc:`queue.ShutDown`.
+
+      By default, gets will only raise once the queue is empty.  Set
+      *immediate* to true to make gets raise immediately instead.
+
+      All blocked callers of put() will be unblocked, and also get()
+      and join() if *immediate* is true.
+
+      .. versionadded:: 3.13
+
    :class:`multiprocessing.Queue` has a few additional methods not found in
    :class:`queue.Queue`.  These methods are usually unnecessary for most
    code:
@@ -962,6 +978,8 @@ For an example of the usage of queues for interprocess communication see
       Raises a :exc:`ValueError` if called more times than there were items
       placed in the queue.
 
+      Raises :exc:`queue.ShutDown` if the queue has been shut down immediately.
+
 
    .. method:: join()
 
@@ -973,6 +991,8 @@ For an example of the usage of queues for interprocess communication see
       it is complete.  When the count of unfinished tasks drops to zero,
       :meth:`~queue.Queue.join` unblocks.
 
+      Raises :exc:`queue.ShutDown` if the queue has been shut down immediately.
+
 
 Miscellaneous
 ~~~~~~~~~~~~~

Lib/multiprocessing/queues.py

@@ -18,7 +18,7 @@
 import weakref
 import errno
 
-from queue import Empty, Full
+from queue import Empty, Full, ShutDown
 
 import _multiprocessing
 
@@ -28,6 +28,10 @@
 
 from .util import debug, info, Finalize, register_after_fork, is_exiting
 
+_queue_alive = 0
+_queue_shutdown = 1
+_queue_shutdown_immediate = 2
+
 #
 # Queue type using a pipe, buffer and thread
 #
@@ -50,18 +54,21 @@ def __init__(self, maxsize=0, *, ctx):
         # For use by concurrent.futures
         self._ignore_epipe = False
         self._reset()
+        self._shutdown_state = ctx.Value('i', _queue_alive)
 
         if sys.platform != 'win32':
             register_after_fork(self, Queue._after_fork)
 
     def __getstate__(self):
         context.assert_spawning(self)
         return (self._ignore_epipe, self._maxsize, self._reader, self._writer,
-                self._rlock, self._wlock, self._sem, self._opid)
+                self._rlock, self._wlock, self._sem, self._opid,
+                self._shutdown_state)
 
     def __setstate__(self, state):
         (self._ignore_epipe, self._maxsize, self._reader, self._writer,
-         self._rlock, self._wlock, self._sem, self._opid) = state
+         self._rlock, self._wlock, self._sem, self._opid,
+         self._shutdown_state) = state
         self._reset()
 
     def _after_fork(self):
@@ -83,10 +90,29 @@ def _reset(self, after_fork=False):
         self._recv_bytes = self._reader.recv_bytes
         self._poll = self._reader.poll
 
+    def _is_alive(self):
+        return self._shutdown_state.value == _queue_alive
+
+    def _is_shutdown(self):
+        return self._shutdown_state.value == _queue_shutdown
+
+    def _is_shutdown_immediate(self):
+        return self._shutdown_state.value == _queue_shutdown_immediate
+
+    def _set_shutdown(self):
+        self._shutdown_state.value = _queue_shutdown
+
+    def _set_shutdown_immediate(self):
+        self._shutdown_state.value = _queue_shutdown_immediate
+
     def put(self, obj, block=True, timeout=None):
         if self._closed:
             raise ValueError(f"Queue {self!r} is closed")
+        if not self._is_alive():
+            raise ShutDown
         if not self._sem.acquire(block, timeout):
+            if not self._is_alive():
+                raise ShutDown
             raise Full
 
         with self._notempty:
@@ -100,24 +126,41 @@ def get(self, block=True, timeout=None):
             raise ValueError(f"Queue {self!r} is closed")
         if block and timeout is None:
             with self._rlock:
+                # checks shutdown state
+                if (self._is_shutdown_immediate()
+                    or (self._is_shutdown() and self.empty())):
+                    raise ShutDown
                 res = self._recv_bytes()
             self._sem.release()
         else:
             if block:
                 deadline = time.monotonic() + timeout
             if not self._rlock.acquire(block, timeout):
+                if (self._is_shutdown_immediate()
+                    or (self._is_shutdown() and self.empty())):
+                    raise ShutDown
                 raise Empty
             try:
                 if block:
                     timeout = deadline - time.monotonic()
                     if not self._poll(timeout):
+                        if not self._is_alive():
+                            raise ShutDown
                         raise Empty
                 elif not self._poll():
+                    if not self._is_alive():
+                        raise ShutDown
                     raise Empty
+
+                # here queue is not empty
+                if self._is_shutdown_immediate():
+                    raise ShutDown
+                # here shutdown state queue is alive or shutdown
                 res = self._recv_bytes()
                 self._sem.release()
             finally:
                 self._rlock.release()
+
         # unserialize the data after having released the lock
         return _ForkingPickler.loads(res)
 
@@ -137,6 +180,19 @@ def get_nowait(self):
     def put_nowait(self, obj):
         return self.put(obj, False)
 
+    def shutdown(self, immediate=False):
+        if self._closed:
+            raise ValueError(f"Queue {self!r} is closed")
+        with self._shutdown_state.get_lock():
+            if self._is_shutdown_immediate():
+                return
+            if immediate:
+                self._set_shutdown_immediate()
+                with self._notempty:
+                    self._notempty.notify_all()
+            else:
+                self._set_shutdown()
+
     def close(self):
         self._closed = True
         close = self._close
@@ -310,7 +366,11 @@ def __setstate__(self, state):
     def put(self, obj, block=True, timeout=None):
         if self._closed:
             raise ValueError(f"Queue {self!r} is closed")
+        if not self._is_alive():
+            raise ShutDown
         if not self._sem.acquire(block, timeout):
+            if not self._is_alive():
+                raise ShutDown
             raise Full
 
         with self._notempty, self._cond:
@@ -322,15 +382,28 @@ def put(self, obj, block=True, timeout=None):
 
     def task_done(self):
         with self._cond:
+            if self._is_shutdown_immediate():
+                raise ShutDown
             if not self._unfinished_tasks.acquire(False):
                 raise ValueError('task_done() called too many times')
             if self._unfinished_tasks._semlock._is_zero():
                 self._cond.notify_all()
 
     def join(self):
         with self._cond:
+            if self._is_shutdown_immediate():
+                raise ShutDown
             if not self._unfinished_tasks._semlock._is_zero():
                 self._cond.wait()
+                if self._is_shutdown_immediate():
+                    raise ShutDown
+
+    def shutdown(self, immediate=False):
+        with self._cond:
+            is_alive = self._is_alive()
+            super().shutdown(immediate)
+            if is_alive:
+                self._cond.notify_all()
 
 #
 # Simplified Queue type -- really just a locked pipe