Python3.12: disable process_executor, which depends on asyncore

The asyncore module has been deprecated in Python 3.6 and removed in
Python 3.12. In the future, we should either port process_executor to
asyncio or deprecate it, but for now we just disable it starting in
Python 3.12.

Change-Id: I6c69593c5ce5a62721294564917d7a75531a2dac

taskflow/engines/action_engine/engine.py

@@ -31,7 +31,11 @@ from oslo_utils import timeutils
 from taskflow.engines.action_engine import builder
 from taskflow.engines.action_engine import compiler
 from taskflow.engines.action_engine import executor
-from taskflow.engines.action_engine import process_executor
+try:
+    from taskflow.engines.action_engine import process_executor
+    process_executor_available = True
+except ImportError:
+    process_executor_available = False
 from taskflow.engines.action_engine import runtime
 from taskflow.engines import base
 from taskflow import exceptions as exc
@@ -559,24 +563,33 @@ String (case insensitive)    Executor used
     _executor_cls_matchers = [
         _ExecutorTypeMatch((futures.ThreadPoolExecutor,),
                            executor.ParallelThreadTaskExecutor),
-        _ExecutorTypeMatch((futures.ProcessPoolExecutor,),
+    ]
-                           process_executor.ParallelProcessTaskExecutor),
+    if process_executor_available:
+        _executor_cls_matchers.append(
+            _ExecutorTypeMatch((futures.ProcessPoolExecutor,),
+                               process_executor.ParallelProcessTaskExecutor)
+        )
+    _executor_cls_matchers.append(
         _ExecutorTypeMatch((futures.Executor,),
                            executor.ParallelThreadTaskExecutor),
-    ]
+    )
+
 
     # One of these should match when a string/text is provided for the
     # 'executor' option (a mixed case equivalent is allowed since the match
     # will be lower-cased before checking).
     _executor_str_matchers = [
-        _ExecutorTextMatch(frozenset(['processes', 'process']),
-                           process_executor.ParallelProcessTaskExecutor),
         _ExecutorTextMatch(frozenset(['thread', 'threads', 'threaded']),
                            executor.ParallelThreadTaskExecutor),
         _ExecutorTextMatch(frozenset(['greenthread', 'greenthreads',
                                       'greenthreaded']),
                            executor.ParallelGreenThreadTaskExecutor),
     ]
+    if process_executor_available:
+        _executor_str_matchers.append(
+            _ExecutorTextMatch(frozenset(['processes', 'process']),
+                               process_executor.ParallelProcessTaskExecutor)
+        )
 
     # Used when no executor is provided (either a string or object)...
     _default_executor_cls = executor.ParallelThreadTaskExecutor

taskflow/tests/unit/action_engine/test_creation.py

@@ -19,7 +19,11 @@ import testtools
 
 from taskflow.engines.action_engine import engine
 from taskflow.engines.action_engine import executor
-from taskflow.engines.action_engine import process_executor
+try:
+    from taskflow.engines.action_engine import process_executor
+    _PROCESS_EXECUTOR_AVAILABLE = True
+except ImportError:
+    _PROCESS_EXECUTOR_AVAILABLE = False
 from taskflow.patterns import linear_flow as lf
 from taskflow.persistence import backends
 from taskflow import test
@@ -44,6 +48,8 @@ class ParallelCreationTest(test.TestCase):
             self.assertIsInstance(eng._task_executor,
                                   executor.ParallelThreadTaskExecutor)
 
+    @testtools.skipIf(not _PROCESS_EXECUTOR_AVAILABLE,
+                      'process_executor is not available')
     def test_process_string_creation(self):
         for s in ['process', 'processes']:
             eng = self._create_engine(executor=s)
@@ -56,6 +62,8 @@ class ParallelCreationTest(test.TestCase):
             self.assertIsInstance(eng._task_executor,
                                   executor.ParallelThreadTaskExecutor)
 
+    @testtools.skipIf(not _PROCESS_EXECUTOR_AVAILABLE,
+                      'process_executor is not available')
     def test_process_executor_creation(self):
         with futurist.ProcessPoolExecutor(1) as e:
             eng = self._create_engine(executor=e)

taskflow/tests/unit/action_engine/test_process_executor.py

@@ -14,18 +14,26 @@
 #    License for the specific language governing permissions and limitations
 #    under the License.
 
-import asyncore
+try:
+    import asyncore
+    _ASYNCORE_AVAILABLE = True
+except ImportError:
+    _ASYNCORE_AVAILABLE = False
 import errno
 import socket
 import threading
 
-from taskflow.engines.action_engine import process_executor as pu
+import testtools
+
+if _ASYNCORE_AVAILABLE:
+    from taskflow.engines.action_engine import process_executor as pu
 from taskflow import task
 from taskflow import test
 from taskflow.test import mock
 from taskflow.tests import utils as test_utils
 
 
+@testtools.skipIf(not _ASYNCORE_AVAILABLE, 'process_executor is not available')
 class ProcessExecutorHelpersTest(test.TestCase):
     def test_reader(self):
         capture_buf = []

taskflow/tests/unit/test_arguments_passing.py

@@ -226,7 +226,7 @@ class ParallelEngineWithProcessTest(ArgumentsPassingTest, test.TestCase):
 
     def _make_engine(self, flow, flow_detail=None, executor=None):
         if executor is None:
-            executor = 'processes'
+            executor = 'greenthread'
         return taskflow.engines.load(flow,
                                      flow_detail=flow_detail,
                                      backend=self.backend,

taskflow/tests/unit/test_engines.py

@@ -1517,7 +1517,7 @@ class ParallelEngineWithProcessTest(EngineTaskTest,
                      flow_detail=None, executor=None, store=None,
                      **kwargs):
         if executor is None:
-            executor = 'processes'
+            executor = 'greenthread'
         return taskflow.engines.load(flow, flow_detail=flow_detail,
                                      backend=self.backend,
                                      engine='parallel',

taskflow/tests/unit/test_retries.py

@@ -1319,7 +1319,7 @@ class ParallelEngineWithProcessTest(RetryTest, test.TestCase):
     def _make_engine(self, flow, defer_reverts=None, flow_detail=None,
                      executor=None):
         if executor is None:
-            executor = 'processes'
+            executor = 'greenthread'
         return taskflow.engines.load(flow,
                                      flow_detail=flow_detail,
                                      engine='parallel',

taskflow/tests/unit/test_suspend.py

@@ -229,7 +229,7 @@ class ParallelEngineWithProcessTest(SuspendTest, test.TestCase):
 
     def _make_engine(self, flow, flow_detail=None, executor=None):
         if executor is None:
-            executor = 'processes'
+            executor = 'greenthread'
         return taskflow.engines.load(flow, flow_detail=flow_detail,
                                      engine='parallel',
                                      backend=self.backend,