Enable multi-process training with distributed Coach.

rl_coach/architectures/tensorflow_components/distributed_tf_utils.py

@@ -74,8 +74,8 @@ def create_worker_server_and_device(cluster_spec: tf.train.ClusterSpec, task_ind
     return server.target, device
 
 
-def create_monitored_session(target: tf.train.Server, task_index: int,
-                             checkpoint_dir: str, checkpoint_save_secs: int, config: tf.ConfigProto=None) -> tf.Session:
+def create_monitored_session(target: tf.train.Server, task_index: int, checkpoint_dir: str, checkpoint_save_secs: int,
+                             scaffold: tf.train.Scaffold, config: tf.ConfigProto=None) -> tf.Session:
     """
     Create a monitored session for the worker
     :param target: the target string for the tf.Session

rl_coach/architectures/tensorflow_components/savers.py

@@ -28,7 +28,7 @@ def __init__(self, name):
         # if graph is finalized, savers must have already already been added. This happens
         # in the case of a MonitoredSession
         self._variables = tf.global_variables()
-        
+
         # target network is never saved or restored directly from checkpoint, so we are removing all its variables from the list
         # the target network would be synched back from the online network in graph_manager.improve(...), at the beginning of the run flow.
         self._variables = [v for v in self._variables if '/target' not in v.name]

rl_coach/base_parameters.py

@@ -583,8 +583,8 @@ def __init__(self, framework_type: Frameworks=Frameworks.tensorflow, evaluate_on
 
 
 class DistributedTaskParameters(TaskParameters):
-    def __init__(self, framework_type: Frameworks, parameters_server_hosts: str, worker_hosts: str, job_type: str,
-                 task_index: int, evaluate_only: int=None, num_tasks: int=None,
+    def __init__(self, framework_type: Frameworks=None, parameters_server_hosts: str=None, worker_hosts: str=None,
+                 job_type: str=None, task_index: int=None, evaluate_only: int=None, num_tasks: int=None,
                  num_training_tasks: int=None, use_cpu: bool=False, experiment_path=None, dnd=None,
                  shared_memory_scratchpad=None, seed=None, checkpoint_save_secs=None, checkpoint_restore_dir=None,
                  checkpoint_save_dir=None, export_onnx_graph: bool=False, apply_stop_condition: bool=False):

rl_coach/coach.py

@@ -34,7 +34,8 @@
 from multiprocessing.managers import BaseManager
 import subprocess
 from rl_coach.graph_managers.graph_manager import HumanPlayScheduleParameters, GraphManager
-from rl_coach.utils import list_all_presets, short_dynamic_import, get_open_port, SharedMemoryScratchPad, get_base_dir
+from rl_coach.utils import list_all_presets, short_dynamic_import, get_open_port, SharedMemoryScratchPad, \
+    get_base_dir, start_multi_threaded_learning
 from rl_coach.graph_managers.basic_rl_graph_manager import BasicRLGraphManager
 from rl_coach.environments.environment import SingleLevelSelection
 from rl_coach.memories.backend.redis import RedisPubSubMemoryBackendParameters
@@ -87,6 +88,17 @@ def start_graph(graph_manager: 'GraphManager', task_parameters: 'TaskParameters'
 
 def handle_distributed_coach_tasks(graph_manager, args, task_parameters):
     ckpt_inside_container = "/checkpoint"
+    non_dist_task_parameters = TaskParameters(
+        framework_type=args.framework,
+        evaluate_only=args.evaluate,
+        experiment_path=args.experiment_path,
+        seed=args.seed,
+        use_cpu=args.use_cpu,
+        checkpoint_save_secs=args.checkpoint_save_secs,
+        checkpoint_save_dir=args.checkpoint_save_dir,
+        export_onnx_graph=args.export_onnx_graph,
+        apply_stop_condition=args.apply_stop_condition
+    )
 
     memory_backend_params = None
     if args.memory_backend_params:
@@ -102,15 +114,18 @@ def handle_distributed_coach_tasks(graph_manager, args, task_parameters):
         graph_manager.data_store_params = data_store_params
 
     if args.distributed_coach_run_type == RunType.TRAINER:
+        if not args.distributed_training:
+            task_parameters = non_dist_task_parameters
         task_parameters.checkpoint_save_dir = ckpt_inside_container
         training_worker(
             graph_manager=graph_manager,
             task_parameters=task_parameters,
+            args=args,
             is_multi_node_test=args.is_multi_node_test
         )
 
     if args.distributed_coach_run_type == RunType.ROLLOUT_WORKER:
-        task_parameters.checkpoint_restore_dir = ckpt_inside_container
+        non_dist_task_parameters.checkpoint_restore_dir = ckpt_inside_container
 
         data_store = None
         if args.data_store_params:
@@ -120,7 +135,7 @@ def handle_distributed_coach_tasks(graph_manager, args, task_parameters):
             graph_manager=graph_manager,
             data_store=data_store,
             num_workers=args.num_workers,
-            task_parameters=task_parameters
+            task_parameters=non_dist_task_parameters
         )
 
 
@@ -552,6 +567,11 @@ def get_argument_parser(self) -> argparse.ArgumentParser:
         parser.add_argument('-dc', '--distributed_coach',
                             help="(flag) Use distributed Coach.",
                             action='store_true')
+        parser.add_argument('-dt', '--distributed_training',
+                            help="(flag) Use distributed training with Coach."
+                                 "Used only with --distributed_coach flag."
+                                 "Ignored if --distributed_coach flag is not used.",
+                            action='store_true')
         parser.add_argument('-dcp', '--distributed_coach_config_path',
                             help="(string) Path to config file when using distributed rollout workers."
                                  "Only distributed Coach parameters should be provided through this config file."
@@ -607,18 +627,31 @@ def run_graph_manager(self, graph_manager: 'GraphManager', args: argparse.Namesp
             atexit.register(logger.summarize_experiment)
             screen.change_terminal_title(args.experiment_name)
 
-        task_parameters = TaskParameters(
-            framework_type=args.framework,
-            evaluate_only=args.evaluate,
-            experiment_path=args.experiment_path,
-            seed=args.seed,
-            use_cpu=args.use_cpu,
-            checkpoint_save_secs=args.checkpoint_save_secs,
-            checkpoint_restore_dir=args.checkpoint_restore_dir,
-            checkpoint_save_dir=args.checkpoint_save_dir,
-            export_onnx_graph=args.export_onnx_graph,
-            apply_stop_condition=args.apply_stop_condition
-        )
+        if args.num_workers == 1:
+            task_parameters = TaskParameters(
+                framework_type=args.framework,
+                evaluate_only=args.evaluate,
+                experiment_path=args.experiment_path,
+                seed=args.seed,
+                use_cpu=args.use_cpu,
+                checkpoint_save_secs=args.checkpoint_save_secs,
+                checkpoint_restore_dir=args.checkpoint_restore_dir,
+                checkpoint_save_dir=args.checkpoint_save_dir,
+                export_onnx_graph=args.export_onnx_graph,
+                apply_stop_condition=args.apply_stop_condition
+            )
+        else:
+            task_parameters = DistributedTaskParameters(
+                framework_type=args.framework,
+                use_cpu=args.use_cpu,
+                num_training_tasks=args.num_workers,
+                experiment_path=args.experiment_path,
+                checkpoint_save_secs=args.checkpoint_save_secs,
+                checkpoint_restore_dir=args.checkpoint_restore_dir,
+                checkpoint_save_dir=args.checkpoint_save_dir,
+                export_onnx_graph=args.export_onnx_graph,
+                apply_stop_condition=args.apply_stop_condition
+            )
 
         # open dashboard
         if args.open_dashboard:
@@ -633,78 +666,16 @@ def run_graph_manager(self, graph_manager: 'GraphManager', args: argparse.Namesp
 
         # Single-threaded runs
         if args.num_workers == 1:
-            self.start_single_threaded(task_parameters, graph_manager, args)
+            self.start_single_threaded_learning(task_parameters, graph_manager, args)
         else:
-            self.start_multi_threaded(graph_manager, args)
+            global start_graph
+            start_multi_threaded_learning(start_graph, (graph_manager, task_parameters),
+                                          task_parameters, graph_manager, args)
 
-    def start_single_threaded(self, task_parameters, graph_manager: 'GraphManager', args: argparse.Namespace):
+    def start_single_threaded_learning(self, task_parameters, graph_manager: 'GraphManager', args: argparse.Namespace):
         # Start the training or evaluation
         start_graph(graph_manager=graph_manager, task_parameters=task_parameters)
 
-    def start_multi_threaded(self, graph_manager: 'GraphManager', args: argparse.Namespace):
-        total_tasks = args.num_workers
-        if args.evaluation_worker:
-            total_tasks += 1
-
-        ps_hosts = "localhost:{}".format(get_open_port())
-        worker_hosts = ",".join(["localhost:{}".format(get_open_port()) for i in range(total_tasks)])
-
-        # Shared memory
-        class CommManager(BaseManager):
-            pass
-        CommManager.register('SharedMemoryScratchPad', SharedMemoryScratchPad, exposed=['add', 'get', 'internal_call'])
-        comm_manager = CommManager()
-        comm_manager.start()
-        shared_memory_scratchpad = comm_manager.SharedMemoryScratchPad()
-
-        def start_distributed_task(job_type, task_index, evaluation_worker=False,
-                                   shared_memory_scratchpad=shared_memory_scratchpad):
-            task_parameters = DistributedTaskParameters(
-                framework_type=args.framework,
-                parameters_server_hosts=ps_hosts,
-                worker_hosts=worker_hosts,
-                job_type=job_type,
-                task_index=task_index,
-                evaluate_only=0 if evaluation_worker else None, # 0 value for evaluation worker as it should run infinitely
-                use_cpu=args.use_cpu,
-                num_tasks=total_tasks,  # training tasks + 1 evaluation task
-                num_training_tasks=args.num_workers,
-                experiment_path=args.experiment_path,
-                shared_memory_scratchpad=shared_memory_scratchpad,
-                seed=args.seed+task_index if args.seed is not None else None,  # each worker gets a different seed
-                checkpoint_save_secs=args.checkpoint_save_secs,
-                checkpoint_restore_dir=args.checkpoint_restore_dir,
-                checkpoint_save_dir=args.checkpoint_save_dir,
-                export_onnx_graph=args.export_onnx_graph,
-                apply_stop_condition=args.apply_stop_condition
-            )
-            # we assume that only the evaluation workers are rendering
-            graph_manager.visualization_parameters.render = args.render and evaluation_worker
-            p = Process(target=start_graph, args=(graph_manager, task_parameters))
-            # p.daemon = True
-            p.start()
-            return p
-
-        # parameter server
-        parameter_server = start_distributed_task("ps", 0)
-
-        # training workers
-        # wait a bit before spawning the non chief workers in order to make sure the session is already created
-        workers = []
-        workers.append(start_distributed_task("worker", 0))
-        time.sleep(2)
-        for task_index in range(1, args.num_workers):
-            workers.append(start_distributed_task("worker", task_index))
-
-        # evaluation worker
-        if args.evaluation_worker or args.render:
-            evaluation_worker = start_distributed_task("worker", args.num_workers, evaluation_worker=True)
-
-        # wait for all workers
-        [w.join() for w in workers]
-        if args.evaluation_worker:
-            evaluation_worker.terminate()
-
 
 def main():
     launcher = CoachLauncher()

rl_coach/data_stores/s3_data_store.py

@@ -88,16 +88,20 @@ def save_to_store(self):
             # Acquire lock
             self.mc.put_object(self.params.bucket_name, SyncFiles.LOCKFILE.value, io.BytesIO(b''), 0)
 
+            ckpt_state_filename = CheckpointStateFile.checkpoint_state_filename
             state_file = CheckpointStateFile(os.path.abspath(self.params.checkpoint_dir))
             if state_file.exists():
                 ckpt_state = state_file.read()
+                ckpt_name_prefix = ckpt_state.name
+
+            if ckpt_state_filename is not None and ckpt_name_prefix is not None:
                 checkpoint_file = None
                 for root, dirs, files in os.walk(self.params.checkpoint_dir):
                     for filename in files:
-                        if filename == CheckpointStateFile.checkpoint_state_filename:
+                        if filename == ckpt_state_filename:
                             checkpoint_file = (root, filename)
                             continue
-                        if filename.startswith(ckpt_state.name):
+                        if filename.startswith(ckpt_name_prefix):
                             abs_name = os.path.abspath(os.path.join(root, filename))
                             rel_name = os.path.relpath(abs_name, self.params.checkpoint_dir)
                             self.mc.fput_object(self.params.bucket_name, rel_name, abs_name)
@@ -131,6 +135,8 @@ def load_from_store(self):
         """
         try:
             state_file = CheckpointStateFile(os.path.abspath(self.params.checkpoint_dir))
+            ckpt_state_filename = state_file.filename
+            ckpt_state_file_path = state_file.path
 
             # wait until lock is removed
             while True:
@@ -139,7 +145,7 @@ def load_from_store(self):
                 if next(objects, None) is None:
                     try:
                         # fetch checkpoint state file from S3
-                        self.mc.fget_object(self.params.bucket_name, state_file.filename, state_file.path)
+                        self.mc.fget_object(self.params.bucket_name, ckpt_state_filename, ckpt_state_file_path)
                     except Exception as e:
                         continue
                     break
@@ -156,10 +162,12 @@ def load_from_store(self):
                     )
                 except Exception as e:
                     pass
+            state_file = CheckpointStateFile(os.path.abspath(self.params.checkpoint_dir))
+            ckpt_state = state_file.read()
+            ckpt_name_prefix = ckpt_state.name
 
-            checkpoint_state = state_file.read()
-            if checkpoint_state is not None:
-                objects = self.mc.list_objects_v2(self.params.bucket_name, prefix=checkpoint_state.name, recursive=True)
+            if ckpt_name_prefix is not None:
+                objects = self.mc.list_objects_v2(self.params.bucket_name, prefix=ckpt_name_prefix, recursive=True)
                 for obj in objects:
                     filename = os.path.abspath(os.path.join(self.params.checkpoint_dir, obj.object_name))
                     if not os.path.exists(filename):

rl_coach/graph_managers/graph_manager.py

@@ -226,11 +226,15 @@ def _create_session_tf(self, task_parameters: TaskParameters):
             else:
                 checkpoint_dir = task_parameters.checkpoint_save_dir
 
+            self.checkpoint_saver = tf.train.Saver()
+            scaffold = tf.train.Scaffold(saver=self.checkpoint_saver)
+
             self.sess = create_monitored_session(target=task_parameters.worker_target,
                                                  task_index=task_parameters.task_index,
                                                  checkpoint_dir=checkpoint_dir,
                                                  checkpoint_save_secs=task_parameters.checkpoint_save_secs,
-                                                 config=config)
+                                                 config=config,
+                                                 scaffold=scaffold)
             # set the session for all the modules
             self.set_session(self.sess)
         else:
@@ -258,9 +262,11 @@ def create_session(self, task_parameters: TaskParameters):
             raise ValueError('Invalid framework {}'.format(task_parameters.framework_type))
 
         # Create parameter saver
-        self.checkpoint_saver = SaverCollection()
-        for level in self.level_managers:
-            self.checkpoint_saver.update(level.collect_savers())
+        if not isinstance(task_parameters, DistributedTaskParameters):
+            self.checkpoint_saver = SaverCollection()
+            for level in self.level_managers:
+                self.checkpoint_saver.update(level.collect_savers())
+
         # restore from checkpoint if given
         self.restore_checkpoint()
 
@@ -540,8 +546,9 @@ def improve(self):
         count_end = self.total_steps_counters[RunPhase.TRAIN] + self.improve_steps
         while self.total_steps_counters[RunPhase.TRAIN] < count_end:
             self.train_and_act(self.steps_between_evaluation_periods)
-            if self.evaluate(self.evaluation_steps):
-                break
+            if self.task_parameters.task_index == 0 or self.task_parameters.task_index is None:
+                if self.evaluate(self.evaluation_steps):
+                    break
 
     def restore_checkpoint(self):
         self.verify_graph_was_created()
@@ -599,7 +606,9 @@ def save_checkpoint(self):
         if not isinstance(self.task_parameters, DistributedTaskParameters):
             saved_checkpoint_path = self.checkpoint_saver.save(self.sess, checkpoint_path)
         else:
-            saved_checkpoint_path = checkpoint_path
+            # FIXME: Explicitly managing Saver inside monitored training session is not recommended.
+            # https://github.com/tensorflow/tensorflow/issues/8425#issuecomment-286927528.
+            saved_checkpoint_path = self.checkpoint_saver.save(self.sess._tf_sess(), checkpoint_path)
 
         # this is required in order for agents to save additional information like a DND for example
         [manager.save_checkpoint(checkpoint_name) for manager in self.level_managers]

rl_coach/tests/test_dist_coach.py

@@ -73,7 +73,9 @@ def get_tests():
     """
     tests = [
         'rl_coach/coach.py -p CartPole_ClippedPPO -dc -e sample -dcp {template} --dump_worker_logs -asc --is_multi_node_test --seed 1',
-        'rl_coach/coach.py -p Mujoco_ClippedPPO -lvl inverted_pendulum -dc -e sample -dcp {template} --dump_worker_logs -asc --is_multi_node_test --seed 1'
+        'rl_coach/coach.py -p Mujoco_ClippedPPO -lvl inverted_pendulum -dc -e sample -dcp {template} --dump_worker_logs -asc --is_multi_node_test --seed 1',
+        'rl_coach/coach.py -p CartPole_ClippedPPO -dc -e sample -dcp {template} --dump_worker_logs -asc --is_multi_node_test --seed 1 -n 2',
+        'rl_coach/coach.py -p Mujoco_ClippedPPO -lvl inverted_pendulum -dc -e sample -dcp {template} --dump_worker_logs -asc --is_multi_node_test --seed 1 -n 2'
     ]
     return tests