Potential resource leak when exception occurs during file operation

## Bug Report

### Description
When an exception is raised during a file operation, the file handle may not be properly closed, leading to a resource leak.

### Steps to Reproduce
1. Open a file without using a context manager
2. Raise an exception before closing the file
3. The file handle remains open

### Expected Behavior
File handles should always be closed, even when exceptions occur.

### Suggested Fix
Use a `with` statement (context manager) to ensure the file is always closed:

```python
# Instead of:
f = open('file.txt', 'r')
data = f.read()
f.close()

# Use:
with open('file.txt', 'r') as f:
data = f.read()
```

### Environment
- Python 3.x
- Any OS

This is a common Python pitfall that can cause issues in long-running applications.

No TiDB file, test, or entry point is named; the report only shows a generic Python example, while the repository is a Go database project. First verify whether any affected TiDB code performs the described file operation, then identify a reproducible failure and a project test before defining completion.

Written by the indexing model from the issue text.