python
@@ -6126,7 +6126,8 @@ class ThreadsMixin(BaseMixin):
 # Functions used to create test cases from the base ones in this module
 #
 
-def install_tests_in_module_dict(remote_globs, start_method):
+def install_tests_in_module_dict(remote_globs, start_method,
+                                 only_type=None, exclude_types=False):
     __module__ = remote_globs['__name__']
     local_globs = globals()
     ALL_TYPES = {'processes', 'threads', 'manager'}
@@ -6139,6 +6140,10 @@ def install_tests_in_module_dict(remote_globs, start_method):
                 continue
             assert set(base.ALLOWED_TYPES) <= ALL_TYPES, base.ALLOWED_TYPES
             for type_ in base.ALLOWED_TYPES:
+                if only_type and type_ != only_type:
+                    continue
+                if exclude_types:
+                    continue
                 newname = 'With' + type_.capitalize() + name[1:]
                 Mixin = local_globs[type_.capitalize() + 'Mixin']
                 class Temp(base, Mixin, unittest.TestCase):
@@ -6149,6 +6154,9 @@ class Temp(base, Mixin, unittest.TestCase):
                 Temp.__module__ = __module__
                 remote_globs[newname] = Temp
         elif issubclass(base, unittest.TestCase):
+            if only_type:
+                continue
+
             class Temp(base, object):
                 pass
             Temp.__name__ = Temp.__qualname__ = name

diff --git a/Lib/test/libregrtest/runtest.py b/Lib/test/libregrtest/runtest.py
@@ -150,6 +150,9 @@ def __str__(self) -> str:
 
 SPLITTESTDIRS = {
     "test_asyncio",
+    "test_multiprocessing_fork",
+    "test_multiprocessing_forkserver",
+    "test_multiprocessing_spawn",
 }
 
 # Storage of uncollectable objects

@@ -1,7 +1,6 @@
-import unittest
-import test._test_multiprocessing
-
+import os.path
 import sys
+import unittest
 from test import support
 
 if support.PGO:
@@ -13,7 +12,5 @@
 if sys.platform == 'darwin':
     raise unittest.SkipTest("test may crash on macOS (bpo-33725)")
 
-test._test_multiprocessing.install_tests_in_module_dict(globals(), 'fork')
-
-if __name__ == '__main__':
-    unittest.main()
+def load_tests(*args):
+    return support.load_package_tests(os.path.dirname(__file__), *args)
@@ -0,0 +1,7 @@
+import unittest
+from test._test_multiprocessing import install_tests_in_module_dict
+
+install_tests_in_module_dict(globals(), 'fork', only_type="manager")
+
+if __name__ == '__main__':
+    unittest.main()
@@ -0,0 +1,7 @@
+import unittest
+from test._test_multiprocessing import install_tests_in_module_dict
+
+install_tests_in_module_dict(globals(), 'fork', exclude_types=True)
+
+if __name__ == '__main__':
+    unittest.main()
@@ -0,0 +1,7 @@
+import unittest
+from test._test_multiprocessing import install_tests_in_module_dict
+
+install_tests_in_module_dict(globals(), 'fork', only_type="processes")
+
+if __name__ == '__main__':
+    unittest.main()
@@ -0,0 +1,7 @@
+import unittest
+from test._test_multiprocessing import install_tests_in_module_dict
+
+install_tests_in_module_dict(globals(), 'fork', only_type="threads")
+
+if __name__ == '__main__':
+    unittest.main()
@@ -1,7 +1,6 @@
-import unittest
-import test._test_multiprocessing
-
+import os.path
 import sys
+import unittest
 from test import support
 
 if support.PGO:
@@ -10,7 +9,5 @@
 if sys.platform == "win32":
     raise unittest.SkipTest("forkserver is not available on Windows")
 
-test._test_multiprocessing.install_tests_in_module_dict(globals(), 'forkserver')
-
-if __name__ == '__main__':
-    unittest.main()
+def load_tests(*args):
+    return support.load_package_tests(os.path.dirname(__file__), *args)
@@ -0,0 +1,7 @@
+import unittest
+from test._test_multiprocessing import install_tests_in_module_dict
+
+install_tests_in_module_dict(globals(), 'forkserver', only_type="manager")
+
+if __name__ == '__main__':
+    unittest.main()
@@ -0,0 +1,7 @@
+import unittest
+from test._test_multiprocessing import install_tests_in_module_dict
+
+install_tests_in_module_dict(globals(), 'forkserver', exclude_types=True)
+
+if __name__ == '__main__':
+    unittest.main()
@@ -0,0 +1,7 @@
+import unittest
+from test._test_multiprocessing import install_tests_in_module_dict
+
+install_tests_in_module_dict(globals(), 'forkserver', only_type="processes")
+
+if __name__ == '__main__':
+    unittest.main()
@@ -0,0 +1,7 @@
+import unittest
+from test._test_multiprocessing import install_tests_in_module_dict
+
+install_tests_in_module_dict(globals(), 'forkserver', only_type="threads")
+
+if __name__ == '__main__':
+    unittest.main()
diff --git a/Lib/test/test_multiprocessing_spawn.py b/Lib/test/test_multiprocessing_spawn.py
@@ -0,0 +1,9 @@
+import os.path
+import unittest
+from test import support
+
+if support.PGO:
+    raise unittest.SkipTest("test is not helpful for PGO")
+
+def load_tests(*args):
+    return support.load_package_tests(os.path.dirname(__file__), *args)
@@ -0,0 +1,7 @@
+import unittest
+from test._test_multiprocessing import install_tests_in_module_dict
+
+install_tests_in_module_dict(globals(), 'spawn', only_type="manager")
+
+if __name__ == '__main__':
+    unittest.main()
@@ -0,0 +1,7 @@
+import unittest
+from test._test_multiprocessing import install_tests_in_module_dict
+
+install_tests_in_module_dict(globals(), 'spawn', exclude_types=True)
+
+if __name__ == '__main__':
+    unittest.main()
@@ -0,0 +1,7 @@
+import unittest
+from test._test_multiprocessing import install_tests_in_module_dict
+
+install_tests_in_module_dict(globals(), 'spawn', only_type="processes")
+
+if __name__ == '__main__':
+    unittest.main()
@@ -0,0 +1,7 @@
+import unittest
+from test._test_multiprocessing import install_tests_in_module_dict
+
+install_tests_in_module_dict(globals(), 'spawn', only_type="threads")
+
+if __name__ == '__main__':
+    unittest.main()
diff --git a/Misc/NEWS.d/next/Tests/2023-08-24-04-23-35.gh-issue-108388.mr0MeE.rst b/Misc/NEWS.d/next/Tests/2023-08-24-04-23-35.gh-issue-108388.mr0MeE.rst
@@ -0,0 +1,4 @@
+Split test_multiprocessing_fork, test_multiprocessing_forkserver and
+test_multiprocessing_spawn into test packages. Each package is made of 4
+sub-tests: processes, threads, manager and misc. It allows running more tests
+in parallel and so reduce the total test duration. Patch by Victor Stinner.