[2.12] Use a "fork" multiprocessing context

diff --git a/lib/bb/__init__.py b/lib/bb/__init__.py
index 566835573..605355e1a 100644
--- a/lib/bb/__init__.py
+++ b/lib/bb/__init__.py
@@ -37,6 +37,34 @@  class BBHandledException(Exception):
 import os
 import logging
 from collections import namedtuple
+import multiprocessing as mp
+
+# Python 3.14 changes the default multiprocessing context from "fork" to
+# "forkserver". However, bitbake heavily relies on "fork" behavior to
+# efficiently pass data to the child processes. Places that need this should do:
+#   from bb import multiprocessing
+# in place of
+#   import multiprocessing
+
+class MultiprocessingContext(object):
+    """
+    Multiprocessing proxy object that uses the "fork" context for a property if
+    available, otherwise goes to the main multiprocessing module. This allows
+    it to be a drop-in replacement for the multiprocessing module, but use the
+    fork context
+    """
+    def __init__(self):
+        super().__setattr__("_ctx", mp.get_context("fork"))
+
+    def __getattr__(self, name):
+        if hasattr(self._ctx, name):
+            return getattr(self._ctx, name)
+        return getattr(mp, name)
+
+    def __setattr__(self, name, value):
+        raise AttributeError(f"Unable to set attribute {name}")
+
+multiprocessing = MultiprocessingContext()
 
 
 class NullHandler(logging.Handler):
diff --git a/lib/bb/asyncrpc/serv.py b/lib/bb/asyncrpc/serv.py
index 667217c5c..acdcaf08e 100644
--- a/lib/bb/asyncrpc/serv.py
+++ b/lib/bb/asyncrpc/serv.py
@@ -11,7 +11,7 @@  import os
 import signal
 import socket
 import sys
-import multiprocessing
+from bb import multiprocessing
 import logging
 from .connection import StreamConnection, WebsocketConnection
 from .exceptions import ClientError, ServerError, ConnectionClosedError, InvokeError
diff --git a/lib/bb/cooker.py b/lib/bb/cooker.py
index 1810bcc60..36659cee2 100644
--- a/lib/bb/cooker.py
+++ b/lib/bb/cooker.py
@@ -12,7 +12,7 @@  import enum
 import sys, os, glob, os.path, re, time
 import itertools
 import logging
-import multiprocessing
+from bb import multiprocessing
 import threading
 from io import StringIO, UnsupportedOperation
 from contextlib import closing
diff --git a/lib/bb/server/process.py b/lib/bb/server/process.py
index 4b35be62c..f74b3f1bf 100644
--- a/lib/bb/server/process.py
+++ b/lib/bb/server/process.py
@@ -13,7 +13,7 @@ 
 import bb
 import bb.event
 import logging
-import multiprocessing
+from bb import multiprocessing
 import threading
 import array
 import os
diff --git a/lib/bb/tests/support/httpserver.py b/lib/bb/tests/support/httpserver.py
index 78f766005..03327e923 100644
--- a/lib/bb/tests/support/httpserver.py
+++ b/lib/bb/tests/support/httpserver.py
@@ -3,7 +3,7 @@ 
 #
 
 import http.server
-import multiprocessing
+from bb import multiprocessing
 import os
 import traceback
 import signal
@@ -43,7 +43,7 @@  class HTTPService(object):
         self.process = multiprocessing.Process(target=self.server.server_start, args=[self.root_dir, self.logger])
 
         # The signal handler from testimage.bbclass can cause deadlocks here
-        # if the HTTPServer is terminated before it can restore the standard 
+        # if the HTTPServer is terminated before it can restore the standard
         #signal behaviour
         orig = signal.getsignal(signal.SIGTERM)
         signal.signal(signal.SIGTERM, signal.SIG_DFL)
diff --git a/lib/bb/utils.py b/lib/bb/utils.py
index 083242268..694e79f55 100644
--- a/lib/bb/utils.py
+++ b/lib/bb/utils.py
@@ -12,7 +12,7 @@  import sys
 import errno
 import logging
 import locale
-import multiprocessing
+from bb import multiprocessing
 import importlib
 import importlib.machinery
 import importlib.util
@@ -1198,8 +1198,6 @@  def process_profilelog(fn, pout = None):
 #
 def multiprocessingpool(*args, **kwargs):
 
-    import multiprocessing.pool
-    #import multiprocessing.util
     #multiprocessing.util.log_to_stderr(10)
     # Deal with a multiprocessing bug where signals to the processes would be delayed until the work
     # completes. Putting in a timeout means the signals (like SIGINT/SIGTERM) get processed.
diff --git a/lib/hashserv/tests.py b/lib/hashserv/tests.py
index da3f8e088..124d8aa00 100644
--- a/lib/hashserv/tests.py
+++ b/lib/hashserv/tests.py
@@ -10,7 +10,7 @@  from .server import DEFAULT_ANON_PERMS, ALL_PERMISSIONS
 from bb.asyncrpc import InvokeError
 import hashlib
 import logging
-import multiprocessing
+from bb import multiprocessing
 import os
 import sys
 import tempfile