163 – Remote interactive debugging

Since Python 3.14 that the module pdb has a CLI option that allows you to attach to a running Python process to debug interactively while it’s running.

Suppose you have some buggy and complex business logic:

acc = 0

while True:
    acc += 1

You save this code in the file myscript.py and run it. The program never finishes, so you see it’s running in the process with ID 12345 and you use the module pdb to attach to it:

$ python -m pbd -p 12345

Once you do, the debugger attaches to your program while it’s running. Here, you can see you attached to the program as it was about to run the line acc += 1. Before you do, you may want to **p**rint the value of the variable acc:

> /path/to/script.py(4)<module>()
-> acc += 1
(Pdb) p acc
559642795

Now, you may want to go to the next line of the function and print the value of the variable acc again:

(Pdb) next
> /path/to/script.py(3)<module>()
-> while True:
(Pdb) p acc
559642796