Just let the future executors handle the max workers

Instead of providing and retaining a thread count in
the worker and action engine executors and checking it
and handling the none case, we can just let the future
types handle this already (which they already do). And
when displaying this information in the worker banner
use a new future executor attribute that is the maximum
number of workers that will be ever created.

Change-Id: I765c22936b53cdbb8a90195a764d4c67bcc3f34b

taskflow/engines/action_engine/executor.py

@@ -417,11 +417,8 @@ class ParallelTaskExecutor(TaskExecutor):
 
     def start(self):
         if self._own_executor:
-            if self._max_workers is not None:
-                max_workers = self._max_workers
-            else:
-                max_workers = threading_utils.get_optimal_thread_count()
-            self._executor = self._create_executor(max_workers=max_workers)
+            self._executor = self._create_executor(
+                max_workers=self._max_workers)
 
     def stop(self):
         if self._own_executor:

taskflow/engines/worker_based/worker.py

@@ -98,13 +98,9 @@ System details:
         self._topic = topic
         self._executor = executor
         self._owns_executor = False
-        self._threads_count = -1
         if self._executor is None:
-            if threads_count is not None:
-                self._threads_count = int(threads_count)
-            else:
-                self._threads_count = tu.get_optimal_thread_count()
-            self._executor = futures.ThreadPoolExecutor(self._threads_count)
+            self._executor = futures.ThreadPoolExecutor(
+                max_workers=threads_count)
             self._owns_executor = True
         self._endpoints = self._derive_endpoints(tasks)
         self._exchange = exchange
@@ -139,8 +135,9 @@ System details:
         tpl_params['transport_type'] = transport.driver_type
         tpl_params['connection_uri'] = connection_details.uri
         tpl_params['executor_type'] = reflection.get_class_name(self._executor)
-        if self._threads_count != -1:
-            tpl_params['executor_thread_count'] = self._threads_count
+        threads_count = getattr(self._executor, 'max_workers', None)
+        if threads_count is not None:
+            tpl_params['executor_thread_count'] = threads_count
         if self._endpoints:
             pretty_endpoints = []
             for ep in self._endpoints:

taskflow/tests/unit/worker_based/test_worker.py

@@ -33,7 +33,6 @@ class TestWorker(test.MockTestCase):
         self.broker_url = 'test-url'
         self.exchange = 'test-exchange'
         self.topic = 'test-topic'
-        self.threads_count = 5
         self.endpoint_count = 24
 
         # patch classes
@@ -42,11 +41,6 @@ class TestWorker(test.MockTestCase):
         self.server_mock, self.server_inst_mock = self.patchClass(
             worker.server, 'Server')
 
-        # other mocking
-        self.threads_count_mock = self.patch(
-            'taskflow.engines.worker_based.worker.tu.get_optimal_thread_count')
-        self.threads_count_mock.return_value = self.threads_count
-
     def worker(self, reset_master_mock=False, **kwargs):
         worker_kwargs = dict(exchange=self.exchange,
                              topic=self.topic,
@@ -62,7 +56,7 @@ class TestWorker(test.MockTestCase):
         self.worker()
 
         master_mock_calls = [
-            mock.call.executor_class(self.threads_count),
+            mock.call.executor_class(max_workers=None),
             mock.call.Server(self.topic, self.exchange,
                              self.executor_inst_mock, [],
                              url=self.broker_url,
@@ -70,7 +64,7 @@ class TestWorker(test.MockTestCase):
                              transport=mock.ANY,
                              retry_options=mock.ANY)
         ]
-        self.assertEqual(self.master_mock.mock_calls, master_mock_calls)
+        self.assertEqual(master_mock_calls, self.master_mock.mock_calls)
 
     def test_banner_writing(self):
         buf = six.StringIO()
@@ -84,7 +78,7 @@ class TestWorker(test.MockTestCase):
         self.worker(threads_count=10)
 
         master_mock_calls = [
-            mock.call.executor_class(10),
+            mock.call.executor_class(max_workers=10),
             mock.call.Server(self.topic, self.exchange,
                              self.executor_inst_mock, [],
                              url=self.broker_url,
@@ -92,7 +86,7 @@ class TestWorker(test.MockTestCase):
                              transport=mock.ANY,
                              retry_options=mock.ANY)
         ]
-        self.assertEqual(self.master_mock.mock_calls, master_mock_calls)
+        self.assertEqual(master_mock_calls, self.master_mock.mock_calls)
 
     def test_creation_with_custom_executor(self):
         executor_mock = mock.MagicMock(name='executor')

taskflow/types/futures.py

@@ -114,6 +114,11 @@ class ThreadPoolExecutor(_thread.ThreadPoolExecutor):
             # really want to use anyway).
             super(ThreadPoolExecutor, self).submit)
 
+    @property
+    def max_workers(self):
+        """The max number of workers that this executor will ever have."""
+        return self._max_workers
+
     @property
     def statistics(self):
         """:class:`.ExecutorStatistics` about the executors executions."""
@@ -153,6 +158,11 @@ class ProcessPoolExecutor(_process.ProcessPoolExecutor):
         """Accessor to determine if the executor is alive/active."""
         return not self._shutdown_thread
 
+    @property
+    def max_workers(self):
+        """The max number of workers that this executor will ever have."""
+        return self._max_workers
+
     @property
     def statistics(self):
         """:class:`.ExecutorStatistics` about the executors executions."""