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BUG-HUNT: [data-integrity] MigrationRunner.get_current_revision() creates a new engine without disposing it — connection leak #7743

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opened 2026-04-12 03:22:36 +00:00 by HAL9000 · 3 comments

HAL9000 commented

2026-04-12 03:22:36 +00:00

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Bug Report: Resource Leak — `get_current_revision()` Creates Engine Without Disposing

Severity Assessment

Impact: Each call to get_current_revision() (called indirectly by get_pending_migrations() and check_migrations_needed()) creates a new Engine that is never disposed, leaking the underlying connection pool and file handles for SQLite databases
Likelihood: High — called during every startup in init_or_upgrade() as part of the pending migration check
Priority: Medium

Location

File: src/cleveragents/infrastructure/database/migration_runner.py
Function/Class: MigrationRunner.get_current_revision
Lines: 153–156

Description

get_current_revision() creates a new SQLAlchemy engine via create_engine(self.database_url), uses it to check the current Alembic revision, then discards it without calling engine.dispose(). For file-based SQLite databases, this leaks the connection. The engine's connection pool holds open file handles that are not released until garbage collected.

This is called by get_pending_migrations() (line 168), which is called by check_migrations_needed() (line 196), which is called by init_or_upgrade() during every app startup.

Evidence

# migration_runner.py lines 153-156
def get_current_revision(self) -> str | None:
    engine = create_engine(self.database_url)  # <-- new engine
    with engine.connect() as connection:       # <-- connection pool opened
        context = MigrationContext.configure(connection)
        return context.get_current_revision()
    # engine is NOT disposed -- pool keeps connections open

Contrast with init_or_upgrade() which correctly calls engine.dispose() in a finally block (line 322).

Expected Behavior

The engine created in get_current_revision() should be disposed after use to release connection pool resources.

Actual Behavior

The engine is created, used, and then left for garbage collection. For SQLite databases, this keeps file handles open. Under rapid migration checks (e.g., test suites running many check_migrations_needed() calls), this can exhaust file handles or create lock contention.

Suggested Fix

def get_current_revision(self) -> str | None:
    engine = create_engine(self.database_url)
    try:
        with engine.connect() as connection:
            context = MigrationContext.configure(connection)
            return context.get_current_revision()
    finally:
        engine.dispose()  # release connection pool

TDD Note

After this bug issue is verified, a corresponding Type/Testing issue will be created for TDD.

Automated by CleverAgents Bot
Supervisor: Bug Hunting | Agent: bug-hunter

## Bug Report: Resource Leak — `get_current_revision()` Creates Engine Without Disposing ### Severity Assessment - **Impact**: Each call to `get_current_revision()` (called indirectly by `get_pending_migrations()` and `check_migrations_needed()`) creates a new `Engine` that is never disposed, leaking the underlying connection pool and file handles for SQLite databases - **Likelihood**: High — called during every startup in `init_or_upgrade()` as part of the pending migration check - **Priority**: Medium ### Location - **File**: `src/cleveragents/infrastructure/database/migration_runner.py` - **Function/Class**: `MigrationRunner.get_current_revision` - **Lines**: 153–156 ### Description `get_current_revision()` creates a new SQLAlchemy engine via `create_engine(self.database_url)`, uses it to check the current Alembic revision, then discards it without calling `engine.dispose()`. For file-based SQLite databases, this leaks the connection. The engine's connection pool holds open file handles that are not released until garbage collected. This is called by `get_pending_migrations()` (line 168), which is called by `check_migrations_needed()` (line 196), which is called by `init_or_upgrade()` during every app startup. ### Evidence ```python # migration_runner.py lines 153-156 def get_current_revision(self) -> str | None: engine = create_engine(self.database_url) # <-- new engine with engine.connect() as connection: # <-- connection pool opened context = MigrationContext.configure(connection) return context.get_current_revision() # engine is NOT disposed -- pool keeps connections open ``` Contrast with `init_or_upgrade()` which correctly calls `engine.dispose()` in a `finally` block (line 322). ### Expected Behavior The engine created in `get_current_revision()` should be disposed after use to release connection pool resources. ### Actual Behavior The engine is created, used, and then left for garbage collection. For SQLite databases, this keeps file handles open. Under rapid migration checks (e.g., test suites running many `check_migrations_needed()` calls), this can exhaust file handles or create lock contention. ### Suggested Fix ```python def get_current_revision(self) -> str | None: engine = create_engine(self.database_url) try: with engine.connect() as connection: context = MigrationContext.configure(connection) return context.get_current_revision() finally: engine.dispose() # release connection pool ``` ### Category resource-leak ### TDD Note After this bug issue is verified, a corresponding Type/Testing issue will be created for TDD. --- **Automated by CleverAgents Bot** Supervisor: Bug Hunting | Agent: bug-hunter

HAL9000 added this to the v3.2.0 milestone

2026-04-12 03:41:39 +00:00

HAL9000 referenced this issue

2026-04-12 03:47:56 +00:00

[AUTO-PROJ-OWN] Project Owner Report (Cycle 1) #7724

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2026-04-12 07:15:56 +00:00

freemo added the

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2026-04-12 18:33:48 +00:00

HAL9000 added

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2026-04-14 05:58:37 +00:00

HAL9000 commented

2026-04-14 05:58:37 +00:00

Author

Owner

✅ Verified — Data integrity bug: MigrationRunner creates engine without disposing — connection leak. MoSCoW: Should-have. Priority: Medium.

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

✅ **Verified** — Data integrity bug: MigrationRunner creates engine without disposing — connection leak. MoSCoW: Should-have. Priority: Medium. --- **Automated by CleverAgents Bot** Supervisor: Project Owner | Agent: project-owner-pool-supervisor

HAL9000 commented

2026-04-14 06:11:53 +00:00

Author

Owner

✅ Verified — Data integrity bug: MigrationRunner creates engine without disposing — connection leak. MoSCoW: Should-have. Priority: Medium.

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