FIX: Connection Pooling Resource Cleanup

[bewithgaurav]

Work Item / Issue Reference

GitHub Issue: Closes #267

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Summary

This pull request improves the reliability and testability of the connection pooling logic in mssql_python/pooling.py by ensuring that pool shutdown and cleanup operations are properly tracked and only performed once. It also adds a method to reset the pooling state for testing purposes.

Connection pool shutdown safety:

• Added a _pools_closed flag to the PoolingManager class to track whether pools have already been closed, preventing multiple shutdowns and resource leaks.
• Updated the disable method and the shutdown_pooling function to check _pools_closed before attempting to close pools, ensuring cleanup only happens once. [1] [2]

Testing support:

• Added a _reset_for_testing class method to PoolingManager to reset internal state, making it easier to write reliable tests for pooling behavior.

[Copilot]

Pull Request Overview

This pull request fixes connection pooling resource cleanup by preventing multiple shutdown operations and resource leaks, while also improving test isolation for pooling functionality.

• Adds tracking of pool closure state to prevent double-cleanup operations
• Introduces thread-safe cleanup logic that only runs once when pools are enabled
• Adds a testing utility method to reset pooling state for better test isolation

Reviewed Changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 2 comments.

File	Description
mssql_python/pooling.py	Implements pool closure tracking and thread-safe cleanup logic to prevent resource leaks
tests/test_009_pooling.py	Comprehensive new test suite for pooling functionality including bug fix verification tests
tests/test_003_connection.py	Removes pooling tests that were moved to the dedicated pooling test file

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[github-actions]

📊 Code Coverage Report

🔥 Diff Coverage 71%

🎯 Overall Coverage 74%

📈 Total Lines Covered: 4181 out of 5612 📁 Project: mssql-python

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Diff Coverage

Diff: main...HEAD, staged and unstaged changes

• mssql_python/pooling.py (71.4%): Missing lines 58-61

Summary

• Total: 14 lines
• Missing: 4 lines
• Coverage: 71%

mssql_python/pooling.py

Lines 54-62

  54             cls._pools_closed = False
  55     
  56 @atexit.register
  57 def shutdown_pooling():
! 58     with PoolingManager._lock:
! 59         if PoolingManager._enabled and not PoolingManager._pools_closed:
! 60             ddbc_bindings.close_pooling()
! 61             PoolingManager._pools_closed = True

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📋 Files Needing Attention

📉 Files with overall lowest coverage (click to expand)

mssql_python.pybind.connection.connection.cpp: 67.6%
mssql_python.ddbc_bindings.py: 68.5%
mssql_python.pybind.ddbc_bindings.cpp: 69.3%
mssql_python.pybind.connection.connection_pool.cpp: 78.9%
mssql_python.cursor.py: 79.7%
mssql_python.connection.py: 81.7%
mssql_python.helpers.py: 84.7%
mssql_python.auth.py: 85.3%
mssql_python.type.py: 86.8%
mssql_python.pooling.py: 87.5%

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