Improve multiprocessing stubs (#8202)

Co-authored-by: Shantanu <12621235+hauntsaninja@users.noreply.github.com>

stdlib/multiprocessing/__init__.pyi

@@ -1,18 +1,12 @@
 import sys
-from collections.abc import Callable, Iterable
-from logging import Logger
-from multiprocessing import connection, context, pool, reduction as reducer, synchronize
+from multiprocessing import context, reduction as reducer, synchronize
 from multiprocessing.context import (
     AuthenticationError as AuthenticationError,
-    BaseContext,
     BufferTooShort as BufferTooShort,
-    DefaultContext,
     Process as Process,
     ProcessError as ProcessError,
-    SpawnContext,
     TimeoutError as TimeoutError,
 )
-from multiprocessing.managers import SyncManager
 from multiprocessing.process import active_children as active_children, current_process as current_process
 
 # These are technically functions that return instances of these Queue classes.
@@ -20,15 +14,12 @@ from multiprocessing.process import active_children as active_children, current_
 # multiprocessing.queues or the aliases defined below. See #4266 for discussion.
 from multiprocessing.queues import JoinableQueue as JoinableQueue, Queue as Queue, SimpleQueue as SimpleQueue
 from multiprocessing.spawn import freeze_support as freeze_support
-from typing import Any, TypeVar, overload
-from typing_extensions import Literal, TypeAlias
+from typing import TypeVar
+from typing_extensions import TypeAlias
 
 if sys.version_info >= (3, 8):
     from multiprocessing.process import parent_process as parent_process
 
-if sys.platform != "win32":
-    from multiprocessing.context import ForkContext, ForkServerContext
-
 __all__ = [
     "Array",
     "AuthenticationError",
@@ -92,60 +83,29 @@ _LockType: TypeAlias = synchronize.Lock
 _RLockType: TypeAlias = synchronize.RLock
 _SemaphoreType: TypeAlias = synchronize.Semaphore
 
-# N.B. The functions below are generated at runtime by partially applying
-# multiprocessing.context.BaseContext's methods, so the two signatures should
-# be identical (modulo self).
-
-# Synchronization primitives
-_LockLike: TypeAlias = synchronize.Lock | synchronize.RLock
+# These functions (really bound methods)
+# are all autogenerated at runtime here: https://github.com/python/cpython/blob/600c65c094b0b48704d8ec2416930648052ba715/Lib/multiprocessing/__init__.py#L23
 RawValue = context._default_context.RawValue
 RawArray = context._default_context.RawArray
 Value = context._default_context.Value
 Array = context._default_context.Array
-
-def Barrier(parties: int, action: Callable[..., Any] | None = ..., timeout: float | None = ...) -> _BarrierType: ...
-def BoundedSemaphore(value: int = ...) -> _BoundedSemaphoreType: ...
-def Condition(lock: _LockLike | None = ...) -> _ConditionType: ...
-def Event() -> _EventType: ...
-def Lock() -> _LockType: ...
-def RLock() -> _RLockType: ...
-def Semaphore(value: int = ...) -> _SemaphoreType: ...
-def Pipe(duplex: bool = ...) -> tuple[connection.Connection, connection.Connection]: ...
-def Pool(
-    processes: int | None = ...,
-    initializer: Callable[..., Any] | None = ...,
-    initargs: Iterable[Any] = ...,
-    maxtasksperchild: int | None = ...,
-) -> pool.Pool: ...
-
-# ----- multiprocessing function stubs -----
-def allow_connection_pickling() -> None: ...
-def cpu_count() -> int: ...
-def get_logger() -> Logger: ...
-def log_to_stderr(level: str | int | None = ...) -> Logger: ...
-def Manager() -> SyncManager: ...
-def set_executable(executable: str) -> None: ...
-def set_forkserver_preload(module_names: list[str]) -> None: ...
-def get_all_start_methods() -> list[str]: ...
-def get_start_method(allow_none: bool = ...) -> str | None: ...
-def set_start_method(method: str, force: bool | None = ...) -> None: ...
-
-if sys.platform != "win32":
-    @overload
-    def get_context(method: None = ...) -> DefaultContext: ...
-    @overload
-    def get_context(method: Literal["spawn"]) -> SpawnContext: ...
-    @overload
-    def get_context(method: Literal["fork"]) -> ForkContext: ...
-    @overload
-    def get_context(method: Literal["forkserver"]) -> ForkServerContext: ...
-    @overload
-    def get_context(method: str) -> BaseContext: ...
-
-else:
-    @overload
-    def get_context(method: None = ...) -> DefaultContext: ...
-    @overload
-    def get_context(method: Literal["spawn"]) -> SpawnContext: ...
-    @overload
-    def get_context(method: str) -> BaseContext: ...
+Barrier = context._default_context.Barrier
+BoundedSemaphore = context._default_context.BoundedSemaphore
+Condition = context._default_context.Condition
+Event = context._default_context.Event
+Lock = context._default_context.Lock
+RLock = context._default_context.RLock
+Semaphore = context._default_context.Semaphore
+Pipe = context._default_context.Pipe
+Pool = context._default_context.Pool
+allow_connection_pickling = context._default_context.allow_connection_pickling
+cpu_count = context._default_context.cpu_count
+get_logger = context._default_context.get_logger
+log_to_stderr = context._default_context.log_to_stderr
+Manager = context._default_context.Manager
+set_executable = context._default_context.set_executable
+set_forkserver_preload = context._default_context.set_forkserver_preload
+get_all_start_methods = context._default_context.get_all_start_methods
+get_start_method = context._default_context.get_start_method
+set_start_method = context._default_context.set_start_method
+get_context = context._default_context.get_context

stdlib/multiprocessing/connection.pyi

@@ -58,4 +58,4 @@ def wait(
     object_list: Iterable[Connection | socket.socket | int], timeout: float | None = ...
 ) -> list[Connection | socket.socket | int]: ...
 def Client(address: _Address, family: str | None = ..., authkey: bytes | None = ...) -> Connection: ...
-def Pipe(duplex: bool = ...) -> tuple[Connection, Connection]: ...
+def Pipe(duplex: bool = ...) -> tuple[_ConnectionBase, _ConnectionBase]: ...

stdlib/multiprocessing/context.pyi

@@ -5,6 +5,8 @@ from collections.abc import Callable, Iterable, Sequence
 from ctypes import _CData
 from logging import Logger
 from multiprocessing import queues, synchronize
+from multiprocessing.connection import _ConnectionBase
+from multiprocessing.managers import SyncManager
 from multiprocessing.pool import Pool as _Pool
 from multiprocessing.process import BaseProcess
 from multiprocessing.sharedctypes import SynchronizedArray, SynchronizedBase
@@ -42,12 +44,10 @@ class BaseContext:
     @staticmethod
     def active_children() -> list[BaseProcess]: ...
     def cpu_count(self) -> int: ...
-    # TODO: change return to SyncManager once a stub exists in multiprocessing.managers
-    def Manager(self) -> Any: ...
-    # TODO: change return to Pipe once a stub exists in multiprocessing.connection
-    def Pipe(self, duplex: bool = ...) -> Any: ...
+    def Manager(self) -> SyncManager: ...
+    def Pipe(self, duplex: bool = ...) -> tuple[_ConnectionBase, _ConnectionBase]: ...
     def Barrier(
-        self, parties: int, action: Callable[..., Any] | None = ..., timeout: float | None = ...
+        self, parties: int, action: Callable[..., object] | None = ..., timeout: float | None = ...
     ) -> synchronize.Barrier: ...
     def BoundedSemaphore(self, value: int = ...) -> synchronize.BoundedSemaphore: ...
     def Condition(self, lock: _LockLike | None = ...) -> synchronize.Condition: ...
@@ -61,7 +61,7 @@ class BaseContext:
     def Pool(
         self,
         processes: int | None = ...,
-        initializer: Callable[..., Any] | None = ...,
+        initializer: Callable[..., object] | None = ...,
         initargs: Iterable[Any] = ...,
         maxtasksperchild: int | None = ...,
     ) -> _Pool: ...
@@ -120,7 +120,10 @@ class BaseContext:
         @overload
         def get_context(self, method: str) -> BaseContext: ...
 
-    def get_start_method(self, allow_none: bool = ...) -> str: ...
+    @overload
+    def get_start_method(self, allow_none: Literal[False] = ...) -> str: ...
+    @overload
+    def get_start_method(self, allow_none: bool) -> str | None: ...
     def set_start_method(self, method: str | None, force: bool = ...) -> None: ...
     @property
     def reducer(self) -> str: ...

stdlib/multiprocessing/dummy/__init__.pyi

@@ -3,6 +3,15 @@ import threading
 import weakref
 from collections.abc import Callable, Iterable, Mapping, Sequence
 from queue import Queue as Queue
+from threading import (
+    Barrier as Barrier,
+    BoundedSemaphore as BoundedSemaphore,
+    Condition as Condition,
+    Event as Event,
+    Lock as Lock,
+    RLock as RLock,
+    Semaphore as Semaphore,
+)
 from typing import Any
 from typing_extensions import Literal
 
@@ -28,13 +37,6 @@ __all__ = [
 ]
 
 JoinableQueue = Queue
-Barrier = threading.Barrier
-BoundedSemaphore = threading.BoundedSemaphore
-Condition = threading.Condition
-Event = threading.Event
-Lock = threading.Lock
-RLock = threading.RLock
-Semaphore = threading.Semaphore
 
 class DummyProcess(threading.Thread):
     _children: weakref.WeakKeyDictionary[Any, Any]
@@ -46,7 +48,7 @@ class DummyProcess(threading.Thread):
     def __init__(
         self,
         group: Any = ...,
-        target: Callable[..., Any] | None = ...,
+        target: Callable[..., object] | None = ...,
         name: str | None = ...,
         args: Iterable[Any] = ...,
         kwargs: Mapping[str, Any] = ...,
@@ -67,8 +69,10 @@ class Value:
 
 def Array(typecode: Any, sequence: Sequence[Any], lock: Any = ...) -> array.array[Any]: ...
 def Manager() -> Any: ...
-def Pool(processes: int | None = ..., initializer: Callable[..., Any] | None = ..., initargs: Iterable[Any] = ...) -> Any: ...
+def Pool(processes: int | None = ..., initializer: Callable[..., object] | None = ..., initargs: Iterable[Any] = ...) -> Any: ...
 def active_children() -> list[Any]: ...
-def current_process() -> threading.Thread: ...
+
+current_process = threading.current_thread
+
 def freeze_support() -> None: ...
 def shutdown() -> None: ...

stdlib/multiprocessing/managers.pyi

@@ -148,7 +148,7 @@ class BaseManager:
 
     def get_server(self) -> Server: ...
     def connect(self) -> None: ...
-    def start(self, initializer: Callable[..., Any] | None = ..., initargs: Iterable[Any] = ...) -> None: ...
+    def start(self, initializer: Callable[..., object] | None = ..., initargs: Iterable[Any] = ...) -> None: ...
     def shutdown(self) -> None: ...  # only available after start() was called
     def join(self, timeout: float | None = ...) -> None: ...  # undocumented
     @property
@@ -157,7 +157,7 @@ class BaseManager:
     def register(
         cls,
         typeid: str,
-        callable: Callable[..., Any] | None = ...,
+        callable: Callable[..., object] | None = ...,
         proxytype: Any = ...,
         exposed: Sequence[str] | None = ...,
         method_to_typeid: Mapping[str, str] | None = ...,

stdlib/multiprocessing/pool.pyi

@@ -72,7 +72,7 @@ class Pool:
     def __init__(
         self,
         processes: int | None = ...,
-        initializer: Callable[..., None] | None = ...,
+        initializer: Callable[..., object] | None = ...,
         initargs: Iterable[Any] = ...,
         maxtasksperchild: int | None = ...,
         context: Any | None = ...,
@@ -118,7 +118,7 @@ class Pool:
 
 class ThreadPool(Pool):
     def __init__(
-        self, processes: int | None = ..., initializer: Callable[..., Any] | None = ..., initargs: Iterable[Any] = ...
+        self, processes: int | None = ..., initializer: Callable[..., object] | None = ..., initargs: Iterable[Any] = ...
     ) -> None: ...
 
 # undocumented

stdlib/multiprocessing/process.pyi

@@ -15,7 +15,7 @@ class BaseProcess:
     def __init__(
         self,
         group: None = ...,
-        target: Callable[..., Any] | None = ...,
+        target: Callable[..., object] | None = ...,
         name: str | None = ...,
         args: Iterable[Any] = ...,
         kwargs: Mapping[str, Any] = ...,

stdlib/multiprocessing/synchronize.pyi

@@ -4,7 +4,6 @@ from collections.abc import Callable
 from contextlib import AbstractContextManager
 from multiprocessing.context import BaseContext
 from types import TracebackType
-from typing import Any
 from typing_extensions import TypeAlias
 
 __all__ = ["Lock", "RLock", "Semaphore", "BoundedSemaphore", "Condition", "Event"]
@@ -13,7 +12,7 @@ _LockLike: TypeAlias = Lock | RLock
 
 class Barrier(threading.Barrier):
     def __init__(
-        self, parties: int, action: Callable[..., Any] | None = ..., timeout: float | None = ..., *ctx: BaseContext
+        self, parties: int, action: Callable[[], object] | None = ..., timeout: float | None = ..., *ctx: BaseContext
     ) -> None: ...
 
 class BoundedSemaphore(Semaphore):