Debugger skips __init__.py files when launching a module

[ashenstrata]

Environment data

• debugpy version: 1.8.16
• OS and version: macOS 15.6.1
• Python version (& distribution if applicable, e.g. Anaconda): 3.11.13
• Using VS Code or Visual Studio: VS Code

Steps to reproduce:

1. Create a file somepackage/__init__.py with content print("first")
2. Create a file somepackage/main.py with content print("second")
3. Set breakpoints in both files
4. Debug the somepackage.main module either from VS Code or by running: python -m debugpy --listen localhost:5678 --wait-for-client -m somepackage.main

Note that the __init__ module is executed automatically before the main module.

Sample: https://github.com/ashenstrata/sample-debugpy-1

Actual behavior

The debugger skips __init__.py and "first" always gets printed. Only after that, the debugger kicks in and pauses execution (either at the second breakpoint or because of --wait-for-client).

Expected behavior

The debugger initiates before __init__.py is executed, and stops at the first breakpoint.

[rchiodo]

How are you starting this app? It works for me but I have to import main in a different file.

Debugging somepackage.main by itself won't load the __init__.py well because you're loading the main module itself. That never prints the 'init' in the __init__.py.

[rchiodo]

Here's what I tried:

# main.py
print("inside main")

if __name__ == "__main__":
    print("inside main guard")

# __init__.py
print("inside init")

# test.py (one level up)
import somepackage.main

print('inside test')

Running somepackage.main doesn't print the init method. Even from the command line without the debugger. Running the test.py or debugging test.py prints the init and allows me to stop on the init. Something has to import the package for the __init__.py to load.

[ashenstrata]

I don't import anything anywhere. I just run the somepackage.main module. Using python -m somepackage.main, or with debugpy as mentioned above. Both print statements get executed.

I'll create a small sample on GitHub in a few minutes.

[ashenstrata]

Here's the sample: https://github.com/ashenstrata/sample-debugpy-1

See the README. You can clone it or run it right in the browser.

[rchiodo]

Ah I wasn't debugging the module. I was debugging the python file. Debugging the module should load the __init__. Not sure why the breakpoint isn't binding.

[rchiodo]

It seems to me we don't even get called by the python internals for the code loading in the __init__.py. This may not be possible to debug.

[rchiodo]

Yeah even 'pdb' behaves the same way:

PS C:\Users\rchiodo\source\testing\test_debug_init> python -m pdb -m somepackage.main
inside init

c:\users\rchiodo\source\testing\test_debug_init\somepackage\main.py(1)()
-> print("inside main")
(Pdb)

It doesn't stop on the __init__.py code as the first line to execute.

I think the only way to debug this is to load the module in another file and debug that file.