Merge pull request #1050 from Avaiga/feature/#986-document-best-pract…

…ice-on-main-script

Feature/#986 - Document best practice on main script

docs/manuals/userman/configuration/job-config.md

@@ -85,10 +85,17 @@ You can configure the *standalone* mode with the following config:
 To execute multiple `Job^`s simultaneously, you can set the *max_nb_of_workers* to an
 integer value greater than 1. That starts each `Job^` in a dedicated process with
 *max_nb_of_workers* as the limit of concurrent processes that can run simultaneously.
+The default value of *max_nb_of_workers* is 2.
 
-!!! note
+!!! warning
 
-    The default value of *max_nb_of_workers* is 2.
+    In *standalone* mode, when a subprocess is spawned, the code is re-executed except
+    for the code inside the `if __name__ == "__main__":` condition. This can lead to
+    unexpected behavior if the code is not protected.
+
+    Therefore, it's a good practice to protect the main code with the `if __name__ == "__main":`
+    condition in your Taipy application main script. By doing this, the code will not be re-executed
+    when the subprocesses are spawned.
 
 For example, the following configuration will allow Taipy to run up to eight `Job^`s
 simultaneously:
@@ -98,15 +105,19 @@ simultaneously:
     ```python  linenums="1"
     from taipy import Config
 
-    Config.configure_job_executions(mode="standalone", max_nb_of_workers=8)
+    if __name__ == "__main__":
+        Config.configure_job_executions(mode="standalone", max_nb_of_workers=8)
+        ...
     ```
 
 === "TOML configuration "
 
     ```python linenums="1"
     from taipy import Config
 
-    Config.load("config.toml")
+    if __name__ == "__main__":
+        Config.load("config.toml")
+        ...
     ```
 
     ```toml linenums="1" title="config.toml"

docs/manuals/userman/data-integration/code-example/data-node-history/data-node-history-example.py

@@ -1,32 +1,32 @@
 import random
+
 import taipy as tp
 from taipy import Config
 
 
 def random_value():
     return random.randint(0, 100)
 
+if __name__ == "__main__":
+    # Configure a data node, a tasks and a scenario
+    int_cfg = Config.configure_data_node("random_val", scope=tp.Scope.GLOBAL, default_data=12)
+    task_cfg = Config.configure_task("random_task", function=random_value, output=int_cfg)
+    scenario_cfg = Config.configure_scenario("random_scenario", task_configs=[task_cfg])
 
-# Configure a data node, a tasks and a scenario
-int_cfg = Config.configure_data_node("random_val", scope=tp.Scope.GLOBAL, default_data=12)
-task_cfg = Config.configure_task("random_task", function=random_value, output=int_cfg)
-scenario_cfg = Config.configure_scenario("random_scenario", task_configs=[task_cfg])
-
-# Create a data node along with a scenario. A default value is written automatically
-scenario = tp.create_scenario(scenario_cfg)
-data_node = scenario.random_val
-
-# Manually write a new value to the data node
-data_node.write(100, editor="John", comment="Manual edition: 100", extra="extra data")
+    # Create a data node along with a scenario. A default value is written automatically
+    scenario = tp.create_scenario(scenario_cfg)
+    data_node = scenario.random_val
 
-# Submit the scenario so that the data node is written again through a job
-tp.Core().run()
-scenario.submit()
+    # Manually write a new value to the data node
+    data_node.write(100, editor="John", comment="Manual edition: 100", extra="extra data")
 
-print(data_node.edits)
-# [{'timestamp': datetime.datetime(2024, 5, 14, 20, 12, 27, 652773), 'editor': 'TAIPY', 'comment': 'Default data written.'},
-# {'timestamp': datetime.datetime(2024, 5, 14, 20, 12, 27, 689737), 'editor': 'John', 'comment': 'Manual edition: 100', 'extra': 'extra data'},
-# {'timestamp': datetime.datetime(2024, 5, 14, 20, 12, 27, 856928), 'job_id': 'JOB_random_task_a8031d80-26f7-406e-9b31-33561d0f9ccd'}]
+    # Submit the scenario so that the data node is written again through a job
+    tp.Core().run()
+    scenario.submit()
 
+    print(data_node.edits)
+    # [{'timestamp': datetime.datetime(2024, 5, 14, 20, 12, 27, 652773), 'editor': 'TAIPY', 'comment': 'Default data written.'},
+    # {'timestamp': datetime.datetime(2024, 5, 14, 20, 12, 27, 689737), 'editor': 'John', 'comment': 'Manual edition: 100', 'extra': 'extra data'},
+    # {'timestamp': datetime.datetime(2024, 5, 14, 20, 12, 27, 856928), 'job_id': 'JOB_random_task_a8031d80-26f7-406e-9b31-33561d0f9ccd'}]
 
-tp.Gui("<|{scenario.random_val}|data_node|>").run()
+    tp.Gui("<|{scenario.random_val}|data_node|>").run()

docs/manuals/userman/data-integration/code-example/data-node-vizelmts/data-node-vizelements-default-behavior.py

@@ -1,12 +1,14 @@
 from datetime import datetime
-import taipy
-from taipy import Config, Core, Gui, Scope
+
 import pandas as pd
 
-# Creating a data node variable to be bound to the visual element
-data_node = None
+import taipy
+from taipy import Config, Core, Gui, Scope
 
 if __name__ == "__main__":
+    # Creating a data node variable to be bound to the visual element
+    data_node = None
+
     # Creating various data sources. A CSV file, an integer parameter and a datetime object
     pd.DataFrame({"A": [1, 2, 3], "B": [4, 5, 6]}).to_csv("out.csv")
     parameter, date = 15, datetime.now()

docs/manuals/userman/data-integration/data-node-usage.md

@@ -45,7 +45,8 @@ part of a scenario.
     import taipy as tp
     from my_config import sales_history_cfg
 
-    sale_history_datanode = tp.create_global_data_node(sales_history_cfg)
+    if __name__ == "__main__":
+        sale_history_datanode = tp.create_global_data_node(sales_history_cfg)
     ```
 
 !!! warning
@@ -73,12 +74,13 @@ passing the data node id as a parameter:
     import taipy as tp
     import my_config
 
-    scenario = tp.create_scenario(my_config.monthly_scenario_cfg)
+    if __name__ == "__main__":
+        scenario = tp.create_scenario(my_config.monthly_scenario_cfg)
 
-    data_node = scenario.sales_history
-    data_node_retrieved = scenario.sales_history
-    data_node = tp.get(data_node.id)
-    # data_node == data_node_retrieved
+        data_node = scenario.sales_history
+        data_node_retrieved = scenario.sales_history
+        data_node = tp.get(data_node.id)
+        # data_node == data_node_retrieved
     ```
 
 ## Get data nodes by config_id
@@ -92,21 +94,22 @@ can be directly accessed as attributes by using their config_id:
     import taipy as tp
     import my_config
 
-    # Creating a scenario from a config
-    scenario = tp.create_scenario(my_config.monthly_scenario_cfg)
+    if __name__ == "__main__":
+        # Creating a scenario from a config
+        scenario = tp.create_scenario(my_config.monthly_scenario_cfg)
 
-    # Access the data node 'sales_history' from the scenario
-    scenario.sales_history
+        # Access the data node 'sales_history' from the scenario
+        scenario.sales_history
 
-    # Access the sequence 'sales' from the scenario and
-    # then access the data node 'sales_history' from the sequence
-    sequence = scenario.sales
-    sequence.sales_history
+        # Access the sequence 'sales' from the scenario and
+        # then access the data node 'sales_history' from the sequence
+        sequence = scenario.sales
+        sequence.sales_history
 
-    # Access the task 'training' from the sequence and
-    # then access the data node 'sales_history' from the task
-    task = sequence.training
-    task.sales_history
+        # Access the task 'training' from the sequence and
+        # then access the data node 'sales_history' from the task
+        task = sequence.training
+        task.sales_history
     ```
 
 Data nodes can be retrieved by using `taipy.get_entities_by_config_id()^`
@@ -119,13 +122,14 @@ nodes instantiated from the config_id provided as a parameter.
     import taipy as tp
     import my_config
 
-    # Create 2 scenarios, which will also create 2 trained_model data nodes.
-    scenario_1 = tp.create_scenario(my_config.monthly_scenario_cfg)
-    scenario_2 = tp.create_scenario(my_config.monthly_scenario_cfg)
+    if __name__ == "__main__":
+        # Create 2 scenarios, which will also create 2 trained_model data nodes.
+        scenario_1 = tp.create_scenario(my_config.monthly_scenario_cfg)
+        scenario_2 = tp.create_scenario(my_config.monthly_scenario_cfg)
 
-    # Get all data nodes by config_id, this will return a list of 2 trained_model data nodes
-    # created alongside the 2 scenarios.
-    all_trained_model_dns = tp.get_entities_by_config_id("trained_model")
+        # Get all data nodes by config_id, this will return a list of 2 trained_model data nodes
+        # created alongside the 2 scenarios.
+        all_trained_model_dns = tp.get_entities_by_config_id("trained_model")
     ```
 
 ##  Get all data nodes
@@ -139,16 +143,17 @@ directly accessed as attributes:
     import taipy as tp
     import my_config
 
-    # Creating a scenario from a config
-    scenario = tp.create_scenario(my_config.monthly_scenario_cfg)
+    if __name__ == "__main__":
+        # Creating a scenario from a config
+        scenario = tp.create_scenario(my_config.monthly_scenario_cfg)
 
-    # Access all the data nodes from the scenario
-    scenario.data_nodes
+        # Access all the data nodes from the scenario
+        scenario.data_nodes
 
-    # Access the sequence 'sales' from the scenario and
-    # then access all the data nodes from the sequence
-    sequence = scenario.sales
-    sequence.data_nodes
+        # Access the sequence 'sales' from the scenario and
+        # then access all the data nodes from the sequence
+        sequence = scenario.sales
+        sequence.data_nodes
     ```
 
 All the data nodes can be retrieved using the method `taipy.get_data_nodes()^`
@@ -177,14 +182,15 @@ the type of data node:
     import taipy as tp
     import my_config
 
-    # Creating a scenario from a config
-    scenario = tp.create_scenario(my_config.monthly_scenario_cfg)
+    if __name__ == "__main__":
+        # Creating a scenario from a config
+        scenario = tp.create_scenario(my_config.monthly_scenario_cfg)
 
-    # Retrieve a data node
-    data_node = scenario.sales_history
+        # Retrieve a data node
+        data_node = scenario.sales_history
 
-    # Returns the content stored on the data node
-    data_node.read()
+        # Returns the content stored on the data node
+        data_node.read()
     ```
 
 To write some data on the data node, like the output of a task,
@@ -199,19 +205,20 @@ type) as a parameter and writes it on the data node:
     import taipy as tp
     import my_config
 
-    # Creating a scenario from a config
-    scenario = tp.create_scenario(my_config.monthly_scenario_cfg)
+    if __name__ == "__main__":
+        # Creating a scenario from a config
+        scenario = tp.create_scenario(my_config.monthly_scenario_cfg)
 
-    # Retrieve a data node
-    data_node = scenario.sales_history
+        # Retrieve a data node
+        data_node = scenario.sales_history
 
-    data = [{"product": "a", "qty": "2"}, {"product": "b", "qty": "4"}]
+        data = [{"product": "a", "qty": "2"}, {"product": "b", "qty": "4"}]
 
-    # Writes the dictionary on the data node
-    data_node.write(data)
+        # Writes the dictionary on the data node
+        data_node.write(data)
 
-    # Returns the new data stored on the data node
-    data_retrieved = data_node.read()
+        # Returns the new data stored on the data node
+        data_retrieved = data_node.read()
     ```
 
 ## Pickle
@@ -1120,19 +1127,20 @@ existing data.
     import taipy as tp
     import my_config
 
-    # Creating a scenario from a config
-    scenario = tp.create_scenario(my_config.monthly_scenario_cfg)
+    if __name__ == "__main__":
+        # Creating a scenario from a config
+        scenario = tp.create_scenario(my_config.monthly_scenario_cfg)
 
-    # Retrieve a data node
-    data_node = scenario.sales_history
+        # Retrieve a data node
+        data_node = scenario.sales_history
 
-    data = [{"product": "a", "qty": "2"}, {"product": "b", "qty": "4"}]
+        data = [{"product": "a", "qty": "2"}, {"product": "b", "qty": "4"}]
 
-    # Append the dictionary to the data node
-    data_node.append(data)
+        # Append the dictionary to the data node
+        data_node.append(data)
 
-    # Returns the new data stored on the data node
-    data_retrieved = data_node.read()
+        # Returns the new data stored on the data node
+        data_retrieved = data_node.read()
     ```
 
 !!! warning "Supported data node types"
@@ -1698,17 +1706,18 @@ To get the parent entities of a data node (scenarios, sequences, or tasks) you c
     import taipy as tp
     import my_config
 
-    # Create a scenario from a config
-    scenario = tp.create_scenario(my_config.monthly_scenario_cfg)
+    if __name__ == "__main__":
+        # Create a scenario from a config
+        scenario = tp.create_scenario(my_config.monthly_scenario_cfg)
 
-    # Retrieve a data node
-    data_node = scenario.sales_history
+        # Retrieve a data node
+        data_node = scenario.sales_history
 
-    # Retrieve the parent entities of the data node
-    parent_entities = data_node.get_parents()
-    # {'scenarios': [Scenario 1], 'sequences': [Sequence 1], 'tasks': [Task 1]}
+        # Retrieve the parent entities of the data node
+        parent_entities = data_node.get_parents()
+        # {'scenarios': [Scenario 1], 'sequences': [Sequence 1], 'tasks': [Task 1]}
 
-    # Retrieve the parent entities of the data node
-    tp.get_parents(data_node)
-    # {'scenarios': [Scenario 1], 'sequences': [Sequence 1], 'tasks': [Task 1]}
+        # Retrieve the parent entities of the data node
+        tp.get_parents(data_node)
+        # {'scenarios': [Scenario 1], 'sequences': [Sequence 1], 'tasks': [Task 1]}
     ```