# Potential Race Condition

- ID: python-race-condition
- Severity: MEDIUM
- CWE: Race Condition (CWE-362)
- Languages: Python

## Description

Detects potential race conditions in concurrent Python code.

Common race condition patterns:
1. Global variables accessed from threads without locking
2. TOCTOU (Time-of-check Time-of-use) file operations
3. Shared data structures modified in threads without synchronization
4. Check-then-act patterns without atomicity

Python's GIL doesn't prevent all race conditions, especially with I/O
operations and multi-process code.

## Remediation

Use locks for shared data and atomic operations for file access.

```python
import threading
import os

# Use locks for shared data
lock = threading.Lock()
with lock:
    counter += 1

# Atomic file creation (no TOCTOU)
try:
    fd = os.open(path, os.O_CREAT | os.O_EXCL | os.O_WRONLY)
    os.close(fd)
except FileExistsError:
    pass

# Or use makedirs with exist_ok
os.makedirs(path, exist_ok=True)
```

Learn more: https://shoulder.dev/learn/python/cwe-362/race-condition

## Documentation

[object Object]

## Related Rules

- **Concurrent Slice Access** [HIGH]: 
- **Direct Map Access on Thread-Safe Struct** [HIGH]: 
- **Potential Race Condition** [MEDIUM]: 
- **WaitGroup Misuse** [HIGH]: 
- **Race Condition in Concurrent Operations** [HIGH]: