add doc and fix bug in experiment resume/view (#3524)

docs/en_US/Tutorial/HowToLaunchFromPython.rst

@@ -106,6 +106,12 @@ Please refer to `example usage <./python_api_connect.rst>`__ and code file :gith
 
 .. Note:: You can use ``stop()`` to stop the experiment when connecting to an existing experiment.
 
+Resume/View and Manage a Stopped Experiment
+-------------------------------------------
+
+You can use ``Experiment.resume()`` and ``Experiment.view()`` to resume and view a stopped experiment, these functions behave like ``nnictl resume`` and ``nnictl view``.
+If you want to manage the experiment, set ``wait_completion`` as ``False`` and the functions will return an ``Experiment`` instance. For more parameters, please refer to API.
+
 API
 ---
 

nni/experiment/experiment.py

@@ -202,8 +202,15 @@ def resume(cls, experiment_id: str, port: int, wait_completion: bool = True, deb
         ----------
         experiment_id
             The stopped experiment id.
+        port
+            The port of web UI.
+        wait_completion
+            If true, run in the foreground. If false, run in the background.
+        debug
+            Whether to start in debug mode.
         """
         experiment = Experiment()
+        experiment.id = experiment_id
         experiment.mode = 'resume'
         if wait_completion:
             experiment.run(port, debug)
@@ -212,16 +219,22 @@ def resume(cls, experiment_id: str, port: int, wait_completion: bool = True, deb
             return experiment
 
     @classmethod
-    def view(cls, experiment_id: str, port: int, wait_completion: bool = True, debug: bool = False):
+    def view(cls, experiment_id: str, port: int, wait_completion: bool = True):
         """
         View a stopped experiment.
 
         Parameters
         ----------
         experiment_id
             The stopped experiment id.
+        port
+            The port of web UI.
+        wait_completion
+            If true, run in the foreground. If false, run in the background.
         """
+        debug = False
         experiment = Experiment()
+        experiment.id = experiment_id
         experiment.mode = 'view'
         if wait_completion:
             experiment.run(port, debug)

nni/experiment/launcher.py

@@ -43,10 +43,9 @@ def start_experiment(exp_id: str, config: ExperimentConfig, port: int, debug: bo
         _check_rest_server(port)
         platform = 'hybrid' if isinstance(config.training_service, list) else config.training_service.platform
         _save_experiment_information(exp_id, port, start_time, platform,
-                                     config.experiment_name, proc.pid, config.experiment_working_directory)
-        if mode != 'view':
-            _logger.info('Setting up...')
-            rest.post(port, '/experiment', config.json())
+                                     config.experiment_name, proc.pid, str(config.experiment_working_directory))
+        _logger.info('Setting up...')
+        rest.post(port, '/experiment', config.json())
         return proc
 
     except Exception as e:

nni/experiment/rest.py

@@ -19,7 +19,7 @@ def request(method: str, port: Optional[int], api: str, data: Any = None) -> Any
     if not resp.ok:
         _logger.error('rest request %s %s failed: %s %s', method.upper(), url, resp.status_code, resp.text)
     resp.raise_for_status()
-    if method.lower() in ['get', 'post']:
+    if method.lower() in ['get', 'post'] and len(resp.content) > 0:
         return resp.json()
 
 def get(port: Optional[int], api: str) -> Any:

nni/tools/nnictl/config_utils.py

@@ -2,7 +2,7 @@
 # Licensed under the MIT license.
 
 import os
-import json
+import json_tricks
 import shutil
 import sqlite3
 import time
@@ -92,7 +92,7 @@ def refresh_config(self):
         '''refresh to get latest config'''
         sql = 'select params from ExperimentProfile where id=? order by revision DESC'
         args = (self.experiment_id,)
-        self.config = config_v0_to_v1(json.loads(self.conn.cursor().execute(sql, args).fetchone()[0]))
+        self.config = config_v0_to_v1(json_tricks.loads(self.conn.cursor().execute(sql, args).fetchone()[0]))
 
     def get_config(self):
         '''get a value according to key'''
@@ -155,7 +155,7 @@ def write_file(self):
         '''save config to local file'''
         try:
             with open(self.experiment_file, 'w') as file:
-                json.dump(self.experiments, file, indent=4)
+                json_tricks.dump(self.experiments, file, indent=4)
         except IOError as error:
             print('Error:', error)
             return ''
@@ -165,7 +165,7 @@ def read_file(self):
         if os.path.exists(self.experiment_file):
             try:
                 with open(self.experiment_file, 'r') as file:
-                    return json.load(file)
+                    return json_tricks.load(file)
             except ValueError:
                 return {}
         return {}

ts/nni_manager/core/nnimanager.ts

@@ -198,9 +198,9 @@ class NNIManager implements Manager {
     }
 
     public async resumeExperiment(readonly: boolean): Promise<void> {
-        this.log.info(`Resuming experiment: ${this.experimentProfile.id}`);
         //Fetch back the experiment profile
         const experimentId: string = getExperimentId();
+        this.log.info(`Resuming experiment: ${experimentId}`);
         this.experimentProfile = await this.dataStore.getExperimentProfile(experimentId);
         this.readonly = readonly;
         if (readonly) {