Issue with debugpy affecting objects refcount

Open

#1,854 opened on Mar 4, 2025 7 comments 0 reactions 1 assignee View on GitHub

@rchiodo is already working on this.

Since Mar 4, 2025.

Assessment

This issue has not been assessed yet.

Description

bug needs repro

Environment data

debugpy version: 1.8.1
OS and version: Windows 11
Python version (& distribution if applicable, e.g. Anaconda): Python 3.11
Using VS Code or Visual Studio: VS Code 1.93.1

Actual behavior

Consider snippet below - when executing with a debugger attached it fails with an error below.

    x.resize(4)
ValueError: cannot resize an array that references or is referenced
by another array in this way.
Use the np.resize function or refcheck=False

import numpy as np
import sys

# import debugpy
# debugpy.listen(5678)
# debugpy.wait_for_client()

x = np.ones(3)
print(sys.getrefcount(x))
# ValueError: cannot resize an array that references or is referenced
# by another array in this way.
# Use the np.resize function or refcheck=False
x.resize(4)
print(x)

Investigating I've noticed 3 different behaviours:

Running it just using python test.py - prints 2 as the refcount and produce no errors.
Running it using VS Code's "Debug Python File"

or by uncommenting debugpy part and attaching debugger later - it prints 2 but fails with an error.
Running it with VS Code/debugpy debugger but setting breakpoint at x = np.ones(3) and then stepping through all lines - then it prints 3 and also fails with an error.

Expected behavior

Code execution not to be affected by the debugging process.

Dominant language: Python
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