Debug a Python C/C++ extension in VSCode on Windows

[DavidDuranPerez]

Type: Debugger

Describe the bug

• OS and Version: Windows 10, 64-bit
• VS Code Version: 1.53.2
• C/C++ Extension Version: 1.2.0
• Other extensions you installed (and if the issue persists after disabling them): Python
• Vscode Github issue that redirects me here: issue
• I wouild like to debug a Python C/C++ extension on Windows I have posted a question with full details in StackOverflow, but no suitable answer has been posted. In Linux, it seems to be possible (see Nadiah link). However, on Windows, after attaching a "(gdb) attach" to the active Python process, I cannot stop on any breakpoint of the C code. I can debug a standalone C/C++ application without problems. I am not sure if it is a bug or it is a feature that is not yet available in Windows. Any help is much appreciated.

To Reproduce Please include a code sample and launch.json configuration. Code to reproduce the behavior:

1. Python Code

import os
import greet

pid = os.getpid()

test=2.2

greet.greet('World')

print("hi")

2. C code

#include <Python.h>

static PyObject *
greet_name(PyObject *self, PyObject *args)
{
    const char *name;

    if (!PyArg_ParseTuple(args, "s", &name))
    {
        return NULL;
    }

    printf("Helllo %s!\n", name);

    Py_RETURN_NONE;
}

static PyMethodDef GreetMethods[] = {
    {"greet", greet_name, METH_VARARGS, "Greet an entity."},
    {NULL, NULL, 0, NULL}
};

static struct PyModuleDef greet =
{
    PyModuleDef_HEAD_INIT,
    "greet",     /* name of module */
    "",          /* module documentation, may be NULL */
    -1,          /* size of per-interpreter state of the module, or -1 if the module keeps state in global variables. */
    GreetMethods
};

PyMODINIT_FUNC PyInit_greet(void)
{
    return PyModule_Create(&greet);
}

I compile the C code with GCC 8.1 by running

python setup.py install

3. Setup file

import os

from setuptools import setup, Extension

os.environ["CC"] = "g++-8.1.0"

_DEBUG = True
_DEBUG_LEVEL = 0
# extra_compile_args = sysconfig.get_config_var('CFLAGS').split()
extra_compile_args = ["-Wall", "-Wextra"]
if _DEBUG:
    extra_compile_args += ["-g3", "-O0", "-DDEBUG=%s" % _DEBUG_LEVEL, "-UNDEBUG"]
else:
    extra_compile_args += ["-DNDEBUG", "-O3"]

setup(
    name='greet',
    version='1.0',
    description='Python Package with Hello World C Extension',
    ext_modules=[
        Extension(
            'greet',
            sources=['greetmodule.c'],
            py_limited_api=True,
            extra_compile_args=extra_compile_args)
    ],
)

I even specify O0 option to have all debug symbols.

4. Launch JSON file

"configurations": [
    {
        "name": "(gdb) Attach",
        "type": "cppdbg",
        "request": "attach",
        "program": "venv/Scripts/python",
        "processId": "${command:pickProcess}",
        "MIMode": "gdb",
        // "miDebuggerPath": "/path/to/gdb",
        "setupCommands": [
            {
                "description": "Enable pretty-printing for gdb",
                "text": "-enable-pretty-printing",
                "ignoreFailures": true
            }
        ]
    },
    {
        "name": "Python: Current File",
        "type": "python",
        "request": "launch",
        "program": "${file}",
        "console": "integratedTerminal"
    }
]

Steps that I follow:

1. Add a breakpoint in the python file, run the launch configuration “Python: Current File” and wait until the breakpoint is reached.
2. Run the “(gdb) Attach” launch configuration, select the python interpreter whose path contains “/.vscode/”. In this case, in Windows, I am not getting prompted to enter my user password as it happens in Linux.
3. Set breakpoints in the C++ Files
4. The python debugger is currently stopped at a break point. Switch back from the debugger “(gdb) Attach” to the other debugger “Python: Current File” and press F5 (Continue). In this last step, vscode should automatically jump between the two debuggers between python and c++ code, but I cannot achieve this behavior.

I am able to debug Python and C programs alone, but not together.

Additional context If applicable, please include logging by adding "logging": { "engineLogging": true, "trace": true, "traceResponse": true } in your launch.json Add any other context about the problem here including log or error messages in your Debug Console or Output windows.

[WardenGnaw]

In this last step, vscode should automatically jump between the two debuggers between python and c++ code, but I cannot achieve this behavior.

The issue is that the python debugger and C++ debugger are two separate debug adapters. The C++ debugger does not know if the python debugger is stopped and vice versa. They are querying the process independently and do not know what the other debugger has done to that process. The interesting question is if we can see when the debug request/responses are coming from each adapter and if VS Code can handle the multiple requests at once.

Also, this extension is primarily focused on C/C++ and not mix mode with other languages. We appreciate any help from other users who may be attempting this scenario.

[DavidDuranPerez]

Yes, any help is much appreciated.

Bear also in mind that, theoretically, this works in Linux (see link). Hence, there may be some specific problem related to Windows...

[axelande]

I can just confirm Davids findings.. Feels odd that it seems to work on other platforms than Windows. I'm trying to migrate a large project from visual studio to vscode.

[axelande]

@WardenGnaw Is there anything in particular you need some help with?

[WardenGnaw]

The help wanted is very general since this seems to be a mixed python and c++ debugging scenario issue since individually debugging via C++ is working. I am unsure how the python debugger would cause the gdb attach to not break at breakpoints.

[DavidDuranPerez]

@axelande, I am not familiar with this library, but I am open to help you if you decide to contribute towards fixing the issue.

[roxanadangerm]

@DavidDuranPerez @WardenGnaw I am happy to help to solve this issue. Is there any logs we should look at?

[DavidDuranPerez]

Hi @roxanadangerm glad to hear that. I don't have any log file, just the information I provided. If you tell me how to obtain the log file, I can give it to you that. Thanks.

[jameszhangzq]

Hi @DavidDuranPerez, I'm facing the same problem and have been looking for solutions everywhere but cannot find any, just wondering if you have solved this issue?

[DavidDuranPerez]

Unfortunately, I found no solution. The other alternative has been to have Linux on a hard drive and debug the code there.

On Mon, 13 Nov 2023 at 09:49, jameszhangzq @.***> wrote:

Hi @DavidDuranPerez https://github.com/DavidDuranPerez, I'm facing the same problem and have been looking for solutions everywhere but cannot find any, just wondering if you have solved this issue?

— Reply to this email directly, view it on GitHub https://github.com/microsoft/vscode-cpptools/issues/6974#issuecomment-1807696407, or unsubscribe https://github.com/notifications/unsubscribe-auth/AGDLPXPHXWLAVVZ4BC3PMGLYEHNLHAVCNFSM4XVKVDH2U5DIOJSWCZC7NNSXTN2JONZXKZKDN5WW2ZLOOQ5TCOBQG43DSNRUGA3Q . You are receiving this because you were mentioned.Message ID: @.***>

-- David Durán Pérez Aeronautical Engineer @.***

[mrx23dot]

my guess is start 2 debugger servers one for each language, connect individual VScode instances for each.

Or try to solve it outside vscode with gdb, then just attach vscode as a viewer.