GUI stops refreshing if too many updates

[ruimac]

When I create a progress bar with a Panel widget or if I populate a Listbox with report lines inside a loop that is processing data, even if I refresh the widgets with widget_name.Refresh, after a few cycles, the GUI freezes.
The data is still processed, but I get to visual feedback inside the template.
Is this a known issue? Is there anything that can be done to revive the GUI update inside a cycle?

 

[sajjad1122]

The issue you're experiencing with your GUI freezing while processing data in a loop is common in applications with long-running tasks. The problem arises because the main thread, which is responsible for updating the GUI, is blocked by the processing tasks. Here are a few strategies to fix this:

1. Use DoEvents() or Update():​

If you're using a toolkit like Tkinter in Python or a similar framework, calling a method like Update() or DoEvents() inside the loop allows the GUI to refresh and respond to user inputs while processing the data.

Example for Tkinter:

python
Copy code
import tkinter as tk
from time import sleep

def update_progress():
for i in range(10):
progress_label.config(text=f"Progress: {i+1}/10")
root.update() # Refresh the GUI
sleep(1) # Simulating long task

root = tk.Tk()
progress_label = tk.Label(root, text="Progress: 0/10")
progress_label.pack()
tk.Button(root, text="Start", command=update_progress).pack()
root.mainloop()

2. Use Multithreading or Multiprocessing:​

Offload the long-running task to a separate thread or process. This allows the GUI to remain responsive because the heavy processing is handled in the background. In Python, you can use the threading or multiprocessing modules.

Example using threading in Python:

python
Copy code
import tkinter as tk
import threading
from time import sleep

def long_task():
for i in range(10):
progress_label.config(text=f"Progress: {i+1}/10")
root.update() # Update the GUI
sleep(1) # Simulate processing

def start_task():
threading.Thread(target=long_task).start()

root = tk.Tk()
progress_label = tk.Label(root, text="Progress: 0/10")
progress_label.pack()
tk.Button(root, text="Start", command=start_task).pack()
root.mainloop()

3. Asynchronous Task Handling:​

If your framework supports asynchronous programming (such as Python’s asyncio or JavaScript promises), use asynchronous tasks to keep the UI responsive while running background tasks.

4. Break Down the Loop:​

Another option is to break the long-running loop into smaller chunks and process them incrementally using timers or events. This avoids blocking the GUI thread for extended periods.

By employing one of these methods, you can ensure your GUI remains responsive while data is being processed.

 

[ruimac]

The issue you're experiencing with your GUI freezing while processing data in a loop is common in applications with long-running tasks. The problem arises because the main thread, which is responsible for updating the GUI, is blocked by the processing tasks. Here are a few strategies to fix this:

1. Use DoEvents() or Update():​

If you're using a toolkit like Tkinter in Python or a similar framework, calling a method like Update() or DoEvents() inside the loop allows the GUI to refresh and respond to user inputs while processing the data.

Example for Tkinter:

python
Copy code
import tkinter as tk
from time import sleep

def update_progress():
for i in range(10):
progress_label.config(text=f"Progress: {i+1}/10")
root.update() # Refresh the GUI
sleep(1) # Simulating long task

root = tk.Tk()
progress_label = tk.Label(root, text="Progress: 0/10")
progress_label.pack()
tk.Button(root, text="Start", command=update_progress).pack()
root.mainloop()

2. Use Multithreading or Multiprocessing:​

Offload the long-running task to a separate thread or process. This allows the GUI to remain responsive because the heavy processing is handled in the background. In Python, you can use the threading or multiprocessing modules.

Example using threading in Python:

python
Copy code
import tkinter as tk
import threading
from time import sleep

def long_task():
for i in range(10):
progress_label.config(text=f"Progress: {i+1}/10")
root.update() # Update the GUI
sleep(1) # Simulate processing

def start_task():
threading.Thread(target=long_task).start()

root = tk.Tk()
progress_label = tk.Label(root, text="Progress: 0/10")
progress_label.pack()
tk.Button(root, text="Start", command=start_task).pack()
root.mainloop()

3. Asynchronous Task Handling:​

If your framework supports asynchronous programming (such as Python’s asyncio or JavaScript promises), use asynchronous tasks to keep the UI responsive while running background tasks.

4. Break Down the Loop:​

Another option is to break the long-running loop into smaller chunks and process them incrementally using timers or events. This avoids blocking the GUI thread for extended periods.

By employing one of these methods, you can ensure your GUI remains responsive while data is being processed.

I'm using vbscript, inside Template Wizard.
And I'm adding a Refresh after each change to a gizmo (the equivalent of an Update(). But that still doesn't solve the problem.
A DoEvents would be great, but I believe vbscript doens't have it. I use it in when I'm coding in Xojo and it works great.

 

[alonh]

I think the problem with the template Wizard is that it is not multi thread
If you have a lot of actions (like a loop) you can't do it asynchronously (as far as I know anyway)
I have encountered this many times and to work around it I break apart the loop to small actions and run each of them with a timer