[retiarii] refactor of nas experiment (#4841)

nni/experiment/config/base.py

@@ -54,6 +54,11 @@ class ConfigBase:
     Config objects will remember where they are loaded; therefore relative paths can be resolved smartly.
     If a config object is created with constructor, the base path will be current working directory.
     If it is loaded with ``ConfigBase.load(path)``, the base path will be ``path``'s parent.
+
+    .. attention::
+
+        All the classes that inherit ``ConfigBase`` are not allowed to use ``from __future__ import annotations``,
+        because ``ConfigBase`` uses ``typeguard`` to perform runtime check and it does not support lazy annotations.
     """
 
     def __init__(self, **kwargs):

nni/experiment/config/experiment_config.py

@@ -164,10 +164,11 @@ class ExperimentConfig(ConfigBase):
         # currently I have only seen one issue of this kind
         #Path(self.experiment_working_directory).mkdir(parents=True, exist_ok=True)
 
-        utils.validate_gpu_indices(self.tuner_gpu_indices)
+        if type(self).__name__ != 'RetiariiExeConfig':
+            utils.validate_gpu_indices(self.tuner_gpu_indices)
 
-        if self.tuner is None:
-            raise ValueError('ExperimentConfig: tuner must be set')
+            if self.tuner is None:
+                raise ValueError('ExperimentConfig: tuner must be set')
 
 def _load_search_space_file(search_space_path):
     # FIXME

nni/experiment/experiment.py

@@ -84,20 +84,9 @@ class Experiment:
         else:
             self.config = config_or_platform
 
-    def start(self, port: int = 8080, debug: bool = False, run_mode: RunMode = RunMode.Background) -> None:
-        """
-        Start the experiment in background.
-
-        This method will raise exception on failure.
-        If it returns, the experiment should have been successfully started.
-
-        Parameters
-        ----------
-        port
-            The port of web UI.
-        debug
-            Whether to start in debug mode.
-        """
+    def _start_impl(self, port: int, debug: bool, run_mode: RunMode,
+                    tuner_command_channel: str | None,
+                    tags: list[str] = []) -> ExperimentConfig:
         assert self.config is not None
         if run_mode is not RunMode.Detach:
             atexit.register(self.stop)
@@ -111,7 +100,8 @@ class Experiment:
         log_level = 'debug' if (debug or config.log_level == 'trace') else config.log_level
         start_experiment_logging(self.id, log_file, cast(str, log_level))
 
-        self._proc = launcher.start_experiment(self._action, self.id, config, port, debug, run_mode, self.url_prefix)
+        self._proc = launcher.start_experiment(self._action, self.id, config, port, debug, run_mode,
+                                               self.url_prefix, tuner_command_channel, tags)
         assert self._proc is not None
 
         self.port = port  # port will be None if start up failed
@@ -124,12 +114,27 @@ class Experiment:
         ips = [f'http://{ip}:{port}' for ip in ips if ip]
         msg = 'Web portal URLs: ${CYAN}' + ' '.join(ips)
         _logger.info(msg)
+        return config
 
-    def stop(self) -> None:
+    def start(self, port: int = 8080, debug: bool = False, run_mode: RunMode = RunMode.Background) -> None:
         """
-        Stop the experiment.
+        Start the experiment in background.
+
+        This method will raise exception on failure.
+        If it returns, the experiment should have been successfully started.
+
+        Parameters
+        ----------
+        port
+            The port of web UI.
+        debug
+            Whether to start in debug mode.
+        run_mode
+            Running the experiment in foreground or background
         """
-        _logger.info('Stopping experiment, please wait...')
+        self._start_impl(port, debug, run_mode, None, [])
+
+    def _stop_impl(self) -> None:
         atexit.unregister(self.stop)
 
         stop_experiment_logging(self.id)
@@ -144,8 +149,24 @@ class Experiment:
         self.id = None  # type: ignore
         self.port = None
         self._proc = None
+
+    def stop(self) -> None:
+        """
+        Stop the experiment.
+        """
+        _logger.info('Stopping experiment, please wait...')
+        self._stop_impl()
         _logger.info('Experiment stopped')
 
+    def _wait_completion(self) -> bool:
+        while True:
+            status = self.get_status()
+            if status == 'DONE' or status == 'STOPPED':
+                return True
+            if status == 'ERROR':
+                return False
+            time.sleep(10)
+
     def run(self, port: int = 8080, wait_completion: bool = True, debug: bool = False) -> bool | None:
         """
         Run the experiment.
@@ -159,13 +180,7 @@ class Experiment:
         self.start(port, debug)
         if wait_completion:
             try:
-                while True:
-                    time.sleep(10)
-                    status = self.get_status()
-                    if status == 'DONE' or status == 'STOPPED':
-                        return True
-                    if status == 'ERROR':
-                        return False
+                self._wait_completion()
             except KeyboardInterrupt:
                 _logger.warning('KeyboardInterrupt detected')
                 self.stop()

nni/retiarii/execution/api.py

@@ -2,6 +2,7 @@
 # Licensed under the MIT license.
 
 import time
+import warnings
 from typing import Iterable
 
 from ..graph import Model, ModelStatus
@@ -18,12 +19,12 @@ __all__ = ['get_execution_engine', 'get_and_register_default_listener',
 
 def set_execution_engine(engine: AbstractExecutionEngine) -> None:
     global _execution_engine
-    if _execution_engine is None:
-        _execution_engine = engine
-    else:
-        raise RuntimeError('Execution engine is already set. '
-                           'You should avoid instantiating RetiariiExperiment twice in one process. '
-                           'If you are running in a Jupyter notebook, please restart the kernel.')
+    if _execution_engine is not None:
+        warnings.warn('Execution engine is already set. '
+                      'You should avoid instantiating RetiariiExperiment twice in one process. '
+                      'If you are running in a Jupyter notebook, please restart the kernel.',
+                      RuntimeWarning)
+    _execution_engine = engine
 
 
 def get_execution_engine() -> AbstractExecutionEngine:

nni/retiarii/execution/base.py

 # Copyright (c) Microsoft Corporation.
 # Licensed under the MIT license.
 
+from __future__ import annotations
+
 import logging
 import os
 import random
 import string
 from typing import Any, Dict, Iterable, List
 
+from nni.experiment import rest
+
 from .interface import AbstractExecutionEngine, AbstractGraphListener
 from .utils import get_mutation_summary
 from .. import codegen, utils
@@ -54,12 +58,22 @@ class BaseExecutionEngine(AbstractExecutionEngine):
     Resource management is implemented in this class.
     """
 
-    def __init__(self) -> None:
+    def __init__(self, rest_port: int | None = None, rest_url_prefix: str | None = None) -> None:
         """
         Upon initialization, advisor callbacks need to be registered.
         Advisor will call the callbacks when the corresponding event has been triggered.
         Base execution engine will get those callbacks and broadcast them to graph listener.
+
+        Parameters
+        ----------
+        rest_port
+            The port of the experiment's rest server
+        rest_url_prefix
+            The url prefix of the experiment's rest entry
         """
+        self.port = rest_port
+        self.url_prefix = rest_url_prefix
+
         self._listeners: List[AbstractGraphListener] = []
 
         # register advisor callbacks
@@ -123,8 +137,8 @@ class BaseExecutionEngine(AbstractExecutionEngine):
         return self.resources
 
     def budget_exhausted(self) -> bool:
-        advisor = get_advisor()
-        return advisor.stopping
+        resp = rest.get(self.port, '/check-status', self.url_prefix)
+        return resp['status'] == 'DONE'
 
     @classmethod
     def pack_model_data(cls, model: Model) -> Any:

nni/retiarii/execution/cgo_engine.py

 # Copyright (c) Microsoft Corporation.
 # Licensed under the MIT license.
 
+from __future__ import annotations
+
 import logging
 import os
 import random
 import string
 import time
 import threading
-from typing import Iterable, List, Dict, Tuple
+from typing import Iterable, List, Dict, Tuple, cast
 from dataclasses import dataclass
 
 from nni.common.device import GPUDevice, Device
+from nni.experiment.config.training_services import RemoteConfig
 from .interface import AbstractExecutionEngine, AbstractGraphListener, WorkerInfo
 from .. import codegen, utils
 from ..graph import Model, ModelStatus, MetricData, Node
@@ -31,7 +34,6 @@ class TrialSubmission:
     placement: Dict[Node, Device]
     grouped_models: List[Model]
 
-
 class CGOExecutionEngine(AbstractExecutionEngine):
     """
     The execution engine with Cross-Graph Optimization (CGO).
@@ -41,24 +43,35 @@ class CGOExecutionEngine(AbstractExecutionEngine):
 
     Parameters
     ----------
-    devices : List[Device]
-        Available devices for execution.
-    max_concurrency : int
+    training_service
+        The remote training service config.
+    max_concurrency
         The maximum number of trials to run concurrently.
-    batch_waiting_time: int
+    batch_waiting_time
         Seconds to wait for each batch of trial submission.
         The trials within one batch could apply cross-graph optimization.
+    rest_port
+        The port of the experiment's rest server
+    rest_url_prefix
+        The url prefix of the experiment's rest entry
     """
 
-    def __init__(self, devices: List[Device] = None,
+    def __init__(self, training_service: RemoteConfig,
                  max_concurrency: int = None,
                  batch_waiting_time: int = 60,
+                 rest_port: int | None = None,
+                 rest_url_prefix: str | None = None
                  ) -> None:
+        self.port = rest_port
+        self.url_prefix = rest_url_prefix
+
         self._listeners: List[AbstractGraphListener] = []
         self._running_models: Dict[int, Model] = dict()
         self.logical_plan_counter = 0
         self.available_devices: List[Device] = []
         self.max_concurrency: int = max_concurrency
+
+        devices = self._construct_devices(training_service)
         for device in devices:
             self.available_devices.append(device)
         self.all_devices = self.available_devices.copy()
@@ -88,6 +101,17 @@ class CGOExecutionEngine(AbstractExecutionEngine):
         self._consumer_thread = threading.Thread(target=self._consume_models)
         self._consumer_thread.start()
 
+    def _construct_devices(self, training_service):
+        devices = []
+        if hasattr(training_service, 'machine_list'):
+            for machine in cast(RemoteConfig, training_service).machine_list:
+                assert machine.gpu_indices is not None, \
+                    'gpu_indices must be set in RemoteMachineConfig for CGO execution engine'
+                assert isinstance(machine.gpu_indices, list), 'gpu_indices must be a list'
+                for gpu_idx in machine.gpu_indices:
+                    devices.append(GPUDevice(machine.host, gpu_idx))
+        return devices
+
     def join(self):
         self._stopped = True
         self._consumer_thread.join()

nni/retiarii/experiment/__init__.py

+# Copyright (c) Microsoft Corporation.
+# Licensed under the MIT license.
\ No newline at end of file

nni/retiarii/experiment/config/__init__.py

+# Copyright (c) Microsoft Corporation.
+# Licensed under the MIT license.
+
+from .experiment_config import *
+from .engine_config import *
\ No newline at end of file

nni/retiarii/experiment/config/engine_config.py

+# Copyright (c) Microsoft Corporation.
+# Licensed under the MIT license.
+
+from dataclasses import dataclass
+from typing import Optional, List
+
+from nni.experiment.config.base import ConfigBase
+
+__all__ = ['ExecutionEngineConfig', 'BaseEngineConfig', 'OneshotEngineConfig',
+           'PyEngineConfig', 'CgoEngineConfig', 'BenchmarkEngineConfig']
+
+@dataclass(init=False)
+class ExecutionEngineConfig(ConfigBase):
+    name: str
+
+@dataclass(init=False)
+class PyEngineConfig(ExecutionEngineConfig):
+    name: str = 'py'
+
+@dataclass(init=False)
+class OneshotEngineConfig(ExecutionEngineConfig):
+    name: str = 'oneshot'
+
+@dataclass(init=False)
+class BaseEngineConfig(ExecutionEngineConfig):
+    name: str = 'base'
+    # input used in GraphConverterWithShape. Currently support shape tuple only.
+    dummy_input: Optional[List[int]] = None
+
+@dataclass(init=False)
+class CgoEngineConfig(ExecutionEngineConfig):
+    name: str = 'cgo'
+    max_concurrency_cgo: Optional[int] = None
+    batch_waiting_time: Optional[int] = None
+    # input used in GraphConverterWithShape. Currently support shape tuple only.
+    dummy_input: Optional[List[int]] = None
+
+@dataclass(init=False)
+class BenchmarkEngineConfig(ExecutionEngineConfig):
+    name: str = 'benchmark'
+    benchmark: Optional[str] = None
\ No newline at end of file

nni/retiarii/experiment/config/experiment_config.py

+# Copyright (c) Microsoft Corporation.
+# Licensed under the MIT license.
+
+import os
+from dataclasses import dataclass
+from typing import Any, Union
+
+from nni.experiment.config import utils, ExperimentConfig
+
+from .engine_config import ExecutionEngineConfig
+
+__all__ = ['RetiariiExeConfig']
+
+def execution_engine_config_factory(engine_name):
+    # FIXME: may move this function to experiment utils in future
+    cls = _get_ee_config_class(engine_name)
+    if cls is None:
+        raise ValueError(f'Invalid execution engine name: {engine_name}')
+    return cls()
+
+def _get_ee_config_class(engine_name):
+    for cls in ExecutionEngineConfig.__subclasses__():
+        if cls.name == engine_name:
+            return cls
+    return None
+
+@dataclass(init=False)
+class RetiariiExeConfig(ExperimentConfig):
+    # FIXME: refactor this class to inherit from a new common base class with HPO config
+    search_space: Any = ''
+    trial_code_directory: utils.PathLike = '.'
+    trial_command: str = '_reserved'
+    # new config field for NAS
+    execution_engine: Union[str, ExecutionEngineConfig]
+
+    def __init__(self, training_service_platform: Union[str, None] = None,
+                 execution_engine: Union[str, ExecutionEngineConfig] = 'py',
+                 **kwargs):
+        super().__init__(training_service_platform, **kwargs)
+        self.execution_engine = execution_engine
+
+    def _canonicalize(self, _parents):
+        msg = '{} is not supposed to be set in Retiarii experiment by users, your config is {}.'
+        if self.search_space != '':
+            raise ValueError(msg.format('search_space', self.search_space))
+        # TODO: maybe we should also allow users to specify trial_code_directory
+        if str(self.trial_code_directory) != '.' and not os.path.isabs(self.trial_code_directory):
+            raise ValueError(msg.format('trial_code_directory', self.trial_code_directory))
+        if self.trial_command != '_reserved' and \
+            not self.trial_command.startswith('python3 -m nni.retiarii.trial_entry '):
+            raise ValueError(msg.format('trial_command', self.trial_command))
+
+        if isinstance(self.execution_engine, str):
+            self.execution_engine = execution_engine_config_factory(self.execution_engine)
+        if self.execution_engine.name in ('py', 'base', 'cgo'):
+            # TODO: replace python3 with more elegant approach
+            # maybe use sys.executable rendered in trial side (e.g., trial_runner)
+            self.trial_command = 'python3 -m nni.retiarii.trial_entry ' + self.execution_engine.name
+
+        super()._canonicalize([self])

nni/retiarii/integration_api.py

@@ -22,7 +22,10 @@ def get_advisor() -> 'RetiariiAdvisor':
 
 def register_advisor(advisor: 'RetiariiAdvisor'):
     global _advisor
-    assert _advisor is None
+    if _advisor is not None:
+        warnings.warn('Advisor is already set.'
+                      'You should avoid instantiating RetiariiExperiment twice in one proces.'
+                      'If you are running in a Jupyter notebook, please restart the kernel.')
     _advisor = advisor
 
 

nni/runtime/msg_dispatcher_base.py

@@ -18,8 +18,15 @@ _worker_fast_exit_on_terminate = True
 
 
 class MsgDispatcherBase(Recoverable):
-    """This is where tuners and assessors are not defined yet.
+    """
+    This is where tuners and assessors are not defined yet.
     Inherits this class to make your own advisor.
+
+    .. note::
+
+        The class inheriting MsgDispatcherBase should be instantiated
+        after nnimanager (rest server) is started, so that the object
+        is ready to use right after its instantiation.
     """
 
     def __init__(self, command_channel_url=None):
@@ -27,6 +34,16 @@ class MsgDispatcherBase(Recoverable):
         if command_channel_url is None:
             command_channel_url = dispatcher_env_vars.NNI_TUNER_COMMAND_CHANNEL
         self._channel = TunerCommandChannel(command_channel_url)
+        # NOTE: `connect()` should be put in __init__. First, this `connect()` affects nnimanager's
+        # starting process, without `connect()` nnimanager is blocked in `dispatcher.init()`.
+        # Second, nas experiment uses a thread to execute `run()` of this class, thus, there is
+        # no way to know when the websocket between nnimanager and dispatcher is built. The following
+        # logic may crash is websocket is not built. One example is updating search space. If updating
+        # search space too soon, as the websocket has not been built, the rest api of updating search
+        # space will timeout.
+        # FIXME: this is making unittest happy
+        if not command_channel_url.startswith('ws://_unittest_'):
+            self._channel.connect()
         self.default_command_queue = Queue()
         self.assessor_command_queue = Queue()
         self.default_worker = threading.Thread(target=self.command_queue_worker, args=(self.default_command_queue,))
@@ -39,7 +56,6 @@ class MsgDispatcherBase(Recoverable):
         """
         _logger.info('Dispatcher started')
 
-        self._channel.connect()
         self.default_worker.start()
         self.assessor_worker.start()
 

test/retiarii_test/cgo_mnasnet/base_mnasnet.py

@@ -4,7 +4,6 @@ import warnings
 
 import torch
 import torch.nn as torch_nn
-from torchvision.models.utils import load_state_dict_from_url
 import torch.nn.functional as F
 
 import sys

test/retiarii_test/cgo_mnasnet/test.py

@@ -8,7 +8,7 @@ import nni.retiarii.evaluator.pytorch.cgo.evaluator as cgo
 from nni.retiarii import serialize
 from base_mnasnet import MNASNet
 from nni.experiment import RemoteMachineConfig
-from nni.retiarii.experiment.pytorch import RetiariiExperiment, RetiariiExeConfig
+from nni.retiarii.experiment.pytorch import RetiariiExperiment, RetiariiExeConfig, CgoEngineConfig
 from nni.retiarii.strategy import TPEStrategy
 from torchvision import transforms
 from torchvision.datasets import CIFAR10
@@ -59,8 +59,6 @@ if __name__ == '__main__':
     exp_config.max_trial_number = 10
     exp_config.trial_gpu_number = 1
     exp_config.training_service.reuse_mode = True
-    exp_config.max_concurrency_cgo = 3
-    exp_config.batch_waiting_time = 0
 
     rm_conf = RemoteMachineConfig()
     rm_conf.host = '127.0.0.1'
@@ -73,6 +71,6 @@ if __name__ == '__main__':
     rm_conf.max_trial_number_per_gpu = 3
     
     exp_config.training_service.machine_list = [rm_conf]
-    exp_config.execution_engine = 'cgo'
+    exp_config.execution_engine = CgoEngineConfig(max_concurrency_cgo = 3, batch_waiting_time = 0)
 
-    exp.run(exp_config, 8099)
+    exp.run(exp_config, 8099)
\ No newline at end of file

test/ut/retiarii/test_cgo_engine.py

@@ -9,6 +9,7 @@ from pytorch_lightning.utilities.seed import seed_everything
 from pathlib import Path
 
 import nni
+from nni.experiment.config import RemoteConfig, RemoteMachineConfig
 import nni.runtime.platform.test
 from nni.runtime.tuner_command_channel import legacy as protocol
 import json
@@ -263,13 +264,14 @@ class CGOEngineTest(unittest.TestCase):
         opt = DedupInputOptimizer()
         opt.convert(lp)
 
-        advisor = RetiariiAdvisor('ws://_placeholder_')
+        advisor = RetiariiAdvisor('ws://_unittest_placeholder_')
         advisor._channel = protocol.LegacyCommandChannel()
         advisor.default_worker.start()
         advisor.assessor_worker.start()
 
-        available_devices = [GPUDevice("test", 0), GPUDevice("test", 1), GPUDevice("test", 2), GPUDevice("test", 3)]
-        cgo = CGOExecutionEngine(devices=available_devices, batch_waiting_time=0)
+        remote = RemoteConfig(machine_list=[])
+        remote.machine_list.append(RemoteMachineConfig(host='test', gpu_indices=[0,1,2,3]))
+        cgo = CGOExecutionEngine(training_service=remote, batch_waiting_time=0)
 
         phy_models = cgo._assemble(lp)
         self.assertTrue(len(phy_models) == 1)
@@ -286,13 +288,14 @@ class CGOEngineTest(unittest.TestCase):
         opt = DedupInputOptimizer()
         opt.convert(lp)
 
-        advisor = RetiariiAdvisor('ws://_placeholder_')
+        advisor = RetiariiAdvisor('ws://_unittest_placeholder_')
         advisor._channel = protocol.LegacyCommandChannel()
         advisor.default_worker.start()
         advisor.assessor_worker.start()
 
-        available_devices = [GPUDevice("test", 0), GPUDevice("test", 1)]
-        cgo = CGOExecutionEngine(devices=available_devices, batch_waiting_time=0)
+        remote = RemoteConfig(machine_list=[])
+        remote.machine_list.append(RemoteMachineConfig(host='test', gpu_indices=[0,1]))
+        cgo = CGOExecutionEngine(training_service=remote, batch_waiting_time=0)
 
         phy_models = cgo._assemble(lp)
         self.assertTrue(len(phy_models) == 2)
@@ -311,13 +314,14 @@ class CGOEngineTest(unittest.TestCase):
 
         models = _load_mnist(2)
 
-        advisor = RetiariiAdvisor('ws://_placeholder_')
+        advisor = RetiariiAdvisor('ws://_unittest_placeholder_')
         advisor._channel = protocol.LegacyCommandChannel()
         advisor.default_worker.start()
         advisor.assessor_worker.start()
 
-        cgo_engine = CGOExecutionEngine(devices=[GPUDevice("test", 0), GPUDevice("test", 1),
-                                                 GPUDevice("test", 2), GPUDevice("test", 3)], batch_waiting_time=0)
+        remote = RemoteConfig(machine_list=[])
+        remote.machine_list.append(RemoteMachineConfig(host='test', gpu_indices=[0,1,2,3]))
+        cgo_engine = CGOExecutionEngine(training_service=remote, batch_waiting_time=0)
         set_execution_engine(cgo_engine)
         submit_models(*models)
         time.sleep(3)

test/ut/retiarii/test_engine.py

@@ -25,7 +25,7 @@ class EngineTest(unittest.TestCase):
     def test_base_execution_engine(self):
         nni.retiarii.integration_api._advisor = None
         nni.retiarii.execution.api._execution_engine = None
-        advisor = RetiariiAdvisor('ws://_placeholder_')
+        advisor = RetiariiAdvisor('ws://_unittest_placeholder_')
         advisor._channel = LegacyCommandChannel()
         advisor.default_worker.start()
         advisor.assessor_worker.start()
@@ -42,7 +42,7 @@ class EngineTest(unittest.TestCase):
     def test_py_execution_engine(self):
         nni.retiarii.integration_api._advisor = None
         nni.retiarii.execution.api._execution_engine = None
-        advisor = RetiariiAdvisor('ws://_placeholder_')
+        advisor = RetiariiAdvisor('ws://_unittest_placeholder_')
         advisor._channel = LegacyCommandChannel()
         advisor.default_worker.start()
         advisor.assessor_worker.start()

test/ut/sdk/test_assessor.py

@@ -57,7 +57,7 @@ class AssessorTestCase(TestCase):
         _restore_io()
 
         assessor = NaiveAssessor()
-        dispatcher = MsgDispatcher('ws://_placeholder_', None, assessor)
+        dispatcher = MsgDispatcher('ws://_unittest_placeholder_', None, assessor)
         dispatcher._channel = LegacyCommandChannel()
         msg_dispatcher_base._worker_fast_exit_on_terminate = False
 

test/ut/sdk/test_msg_dispatcher.py

@@ -66,7 +66,7 @@ class MsgDispatcherTestCase(TestCase):
         _restore_io()
 
         tuner = NaiveTuner()
-        dispatcher = MsgDispatcher('ws://_placeholder_', tuner)
+        dispatcher = MsgDispatcher('ws://_unittest_placeholder_', tuner)
         dispatcher._channel = LegacyCommandChannel()
         msg_dispatcher_base._worker_fast_exit_on_terminate = False
 

ts/nni_manager/core/nnimanager.ts

@@ -303,8 +303,11 @@ class NNIManager implements Manager {
         }
 
         this.trainingService.removeTrialJobMetricListener(this.trialJobMetricListener);
+        // NOTE: this sending TERMINATE should be out of the if clause,
+        // because when python dispatcher is started before nnimanager
+        // this.dispatcherPid would not have a valid value (i.e., not >0).
+        this.dispatcher.sendCommand(TERMINATE);
         if (this.dispatcherPid > 0) {
-            this.dispatcher.sendCommand(TERMINATE);
             // gracefully terminate tuner and assessor here, wait at most 30 seconds.
             for (let i: number = 0; i < 30; i++) {
                 if (!await isAlive(this.dispatcherPid)) {