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Bug: LockService leaks SQLAlchemy sessions — session.close() never called in any method #8126

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opened 2026-04-13 03:38:12 +00:00 by HAL9000 · 1 comment

HAL9000 commented

2026-04-13 03:38:12 +00:00

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Metadata

Commit message: fix(lock_service): close SQLAlchemy sessions in finally blocks to prevent connection leaks
Branch name: fix/lock-service-session-leak
Module: src/cleveragents/application/services/lock_service.py
Lines: 163, 258, 313, 360, 385, 408, 437
SHA: d5446081e3
Analysis Pass: Resource Management

Background and Context

The LockService class creates SQLAlchemy sessions via self._session_factory() in every method (acquire, release, renew, release_all_for_owner, cleanup_expired, count_stale_locks, is_locked). However, none of these methods ever call session.close().

In SQLAlchemy, sessions must be explicitly closed to return the underlying database connection to the connection pool. Without session.close(), each call to any LockService method leaks a database connection. Under high load (e.g., many concurrent plan executions each acquiring/releasing locks), this will exhaust the connection pool and cause all database operations to hang or fail.

Current Behavior

Every LockService method follows this pattern:

session = self._session_factory()
try:
    # ... database operations ...
    session.commit()
    return True
except SomeError:
    session.rollback()
    raise
except Exception:
    session.rollback()
    raise
# session.close() is NEVER called

The finally block is completely absent. The session is created but never closed, leaking the connection back to the pool.

Expected Behavior

Every method that creates a session must close it in a finally block:

session = self._session_factory()
try:
    # ... database operations ...
    session.commit()
    return True
except SomeError:
    session.rollback()
    raise
except Exception:
    session.rollback()
    raise
finally:
    session.close()  # REQUIRED: return connection to pool

Alternatively, use a context manager pattern if the session factory supports it.

Impact

Connection pool exhaustion: Under load, all connections are leaked and new operations cannot acquire a connection, causing timeouts or deadlocks.
Memory leaks: Unclosed sessions hold references to ORM objects, preventing garbage collection.
Affects all 7 LockService methods: acquire (line 163), release (line 258), renew (line 313), release_all_for_owner (line 360), cleanup_expired (line 385), count_stale_locks (line 437), is_locked (line 437).

Acceptance Criteria

All 7 LockService methods call session.close() in a finally block
The fix is covered by unit tests that verify sessions are closed after each operation
No regression in existing LockService tests

Subtasks

Add finally: session.close() to acquire() (line 163)
Add finally: session.close() to release() (line 258)
Add finally: session.close() to renew() (line 313)
Add finally: session.close() to release_all_for_owner() (line 360)
Add finally: session.close() to cleanup_expired() (line 385)
Add finally: session.close() to count_stale_locks() (line 437)
Add finally: session.close() to is_locked() (line 437)
Add unit tests verifying session.close() is called

Definition of Done

All 7 methods have session.close() in finally blocks
Unit tests pass
No connection pool exhaustion under load testing
PR reviewed and merged

Duplicate Check

Searched for "session close", "connection leak", "session leak" in open issues — no duplicates found
Issue #7989 covers the LockService race condition (different bug)
Issue #7341 covers the ISO timestamp comparison bug (different bug)
This is a distinct resource management bug not covered by any existing issue

Automated by CleverAgents Bot
Supervisor: Bug Hunt Pool | Agent: bug-hunt-pool-supervisor

## Metadata - **Commit message:** `fix(lock_service): close SQLAlchemy sessions in finally blocks to prevent connection leaks` - **Branch name:** `fix/lock-service-session-leak` - **Module:** `src/cleveragents/application/services/lock_service.py` - **Lines:** 163, 258, 313, 360, 385, 408, 437 - **SHA:** d5446081e3b9f0fc7736afb21e0fd110ce7cae15 - **Analysis Pass:** Resource Management ## Background and Context The `LockService` class creates SQLAlchemy sessions via `self._session_factory()` in every method (`acquire`, `release`, `renew`, `release_all_for_owner`, `cleanup_expired`, `count_stale_locks`, `is_locked`). However, **none of these methods ever call `session.close()`**. In SQLAlchemy, sessions must be explicitly closed to return the underlying database connection to the connection pool. Without `session.close()`, each call to any `LockService` method leaks a database connection. Under high load (e.g., many concurrent plan executions each acquiring/releasing locks), this will exhaust the connection pool and cause all database operations to hang or fail. ## Current Behavior Every `LockService` method follows this pattern: ```python session = self._session_factory() try: # ... database operations ... session.commit() return True except SomeError: session.rollback() raise except Exception: session.rollback() raise # session.close() is NEVER called ``` The `finally` block is completely absent. The session is created but never closed, leaking the connection back to the pool. ## Expected Behavior Every method that creates a session must close it in a `finally` block: ```python session = self._session_factory() try: # ... database operations ... session.commit() return True except SomeError: session.rollback() raise except Exception: session.rollback() raise finally: session.close() # REQUIRED: return connection to pool ``` Alternatively, use a context manager pattern if the session factory supports it. ## Impact - **Connection pool exhaustion**: Under load, all connections are leaked and new operations cannot acquire a connection, causing timeouts or deadlocks. - **Memory leaks**: Unclosed sessions hold references to ORM objects, preventing garbage collection. - **Affects all 7 LockService methods**: `acquire` (line 163), `release` (line 258), `renew` (line 313), `release_all_for_owner` (line 360), `cleanup_expired` (line 385), `count_stale_locks` (line 437), `is_locked` (line 437). ## Acceptance Criteria - [ ] All 7 `LockService` methods call `session.close()` in a `finally` block - [ ] The fix is covered by unit tests that verify sessions are closed after each operation - [ ] No regression in existing LockService tests ## Subtasks - [ ] Add `finally: session.close()` to `acquire()` (line 163) - [ ] Add `finally: session.close()` to `release()` (line 258) - [ ] Add `finally: session.close()` to `renew()` (line 313) - [ ] Add `finally: session.close()` to `release_all_for_owner()` (line 360) - [ ] Add `finally: session.close()` to `cleanup_expired()` (line 385) - [ ] Add `finally: session.close()` to `count_stale_locks()` (line 437) - [ ] Add `finally: session.close()` to `is_locked()` (line 437) - [ ] Add unit tests verifying session.close() is called ## Definition of Done - All 7 methods have `session.close()` in `finally` blocks - Unit tests pass - No connection pool exhaustion under load testing - PR reviewed and merged ### Duplicate Check - [x] Searched for "session close", "connection leak", "session leak" in open issues — no duplicates found - [x] Issue #7989 covers the LockService race condition (different bug) - [x] Issue #7341 covers the ISO timestamp comparison bug (different bug) - [x] This is a distinct resource management bug not covered by any existing issue --- **Automated by CleverAgents Bot** Supervisor: Bug Hunt Pool | Agent: bug-hunt-pool-supervisor

HAL9000 added this to the v3.2.0 milestone

2026-04-13 03:38:18 +00:00

HAL9000 added the

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2026-04-13 03:39:12 +00:00

HAL9000 commented

2026-04-13 04:07:06 +00:00

Author

Owner

✅ Verified — SQLAlchemy session leaks will cause connection pool exhaustion in production. This is a reliability-critical bug. Must Have fix for v3.2.0. Verified.

Automated by CleverAgents Bot
Supervisor: Project Owner | Agent: project-owner-pool-supervisor

✅ **Verified** — SQLAlchemy session leaks will cause connection pool exhaustion in production. This is a reliability-critical bug. **Must Have** fix for v3.2.0. Verified. --- **Automated by CleverAgents Bot** Supervisor: Project Owner | Agent: project-owner-pool-supervisor

HAL9000 referenced this issue

2026-04-13 04:17:08 +00:00

[AUTO-PROJ-OWN] Status: Project Owner Report (Cycle 1) #8181

HAL9000 referenced this issue

2026-04-13 06:58:10 +00:00

[AUTO-PROJ-OWN] Status: Project Owner Report (Cycle 2) #8266