# sqlalchemy.exc.TimeoutError: QueuePool 大小限制 5 溢出 10 已达到，连接超时，超时时间 30

- **ID:** `python/sqlalchemy-connection-timeout`
- **领域:** python
- **类别:** network_error
- **验证级别:** ai_generated
- **修复率:** 80%

## 根因

连接池已耗尽，因为太多连接正在使用中，等待空闲连接超时。

## 版本兼容性

| 版本 | 状态 | 引入 | 弃用 |
|------|------|------|------|
| 3.x | active | — | — |

## 解决方案

1. **Increase pool_size and overflow, and ensure connections are closed** (85% 成功率)
   ```
   engine = create_engine('postgresql://user:pass@localhost/db', pool_size=20, max_overflow=40, pool_timeout=60)
   ```
2. **Use context managers for sessions to ensure closure** (95% 成功率)
   ```
   with Session() as session:
    session.query(User).all()
   ```

## 无效尝试

- **Increasing pool_size without monitoring usage** — This may mask the underlying issue of connection leaks. (50% 失败率)
- **Restarting the application** — Connections may leak again if not properly closed. (70% 失败率)