# RuntimeError: 无法写入正在关闭的传输

- **ID:** `python/aiohttp-cannot-write-after-response-started`
- **领域:** python
- **类别:** runtime_error
- **验证级别:** ai_generated
- **修复率:** 80%

## 根因

客户端断开或响应已完成后，aiohttp 服务器仍尝试向 StreamResponse 写入数据。

## 版本兼容性

| 版本 | 状态 | 引入 | 弃用 |
|------|------|------|------|
| 3.8+ | active | — | — |
| 3.9+ | active | — | — |
| 3.10+ | active | — | — |
| 3.11+ | active | — | — |

## 解决方案

1. **** (90% 成功率)
   ```
   if request.transport is None or request.transport.is_closing():
    return
await resp.write(chunk)
   ```
2. **** (88% 成功率)
   ```
   resp = web.StreamResponse()
await resp.prepare(request)
try:
    async for chunk in source:
        await resp.write(chunk)
except (ConnectionResetError, RuntimeError):
    pass
finally:
    await resp.write_eof()
   ```

## 无效尝试

- **** — Silently drops data and may hide application logic bugs. (70% 失败率)
- **** — The transport is already closing; timeout is unrelated. (85% 失败率)