# sqlalchemy.exc.TimeoutError: QueuePool limit of size 5 overflow 10 reached, connection timed out, timeout 30

- **ID:** `python/sqlalchemy-timeout-connection-pool`
- **Domain:** python
- **Category:** network_error
- **Verification:** ai_generated
- **Fix Rate:** 80%

## Root Cause

Connection pool exhausted due to too many concurrent requests or slow queries.

## Version Compatibility

| Version | Status | Introduced | Deprecated |
|---------|--------|------------|------------|
| 3.x | active | — | — |

## Workarounds

1. **Optimize pool settings based on load.** (85% success)
   ```
   engine = create_engine(url, pool_size=10, max_overflow=20, pool_timeout=60)
   ```
2. **Use connection pooling monitoring and release connections promptly.** (90% success)
   ```
   with engine.connect() as conn:
    # use connection
    pass  # automatically returned to pool
   ```

## Dead Ends

- **Increasing pool_size and max_overflow to very high values.** — May overwhelm database server with too many connections. (60% fail)
- **Disabling connection pooling entirely.** — Creates new connection for each request, increasing latency. (70% fail)