# asyncio异常：在超时时间内无法获取信号量

- **ID:** `python/asyncio-semaphore-timeout`
- **领域:** python
- **类别:** runtime_error
- **验证级别:** ai_generated
- **修复率:** 80%

## 根因

在高竞争情况下，对信号量acquire()使用asyncio.wait_for()导致超时。

## 版本兼容性

| 版本 | 状态 | 引入 | 弃用 |
|------|------|------|------|
| 3.8 | active | — | — |
| 3.9 | active | — | — |
| 3.10 | active | — | — |

## 解决方案

1. **** (85% 成功率)
   ```
   async with asyncio.timeout(5): await sem.acquire()
   ```
2. **** (80% 成功率)
   ```
   for i in range(3): try: await asyncio.wait_for(sem.acquire(), 1); break except TimeoutError: pass
   ```

## 无效尝试

- **** — May still fail under heavy load; doesn't address root cause. (60% 失败率)
- **** — Leads to resource exhaustion and potential system instability. (70% 失败率)