# 协程和恢复（recover）

一个用到 `recover` 的程序（参见第 13.3 节）停掉了服务器内部一个失败的协程而不影响其他协程的工作。

```go
func server(workChan <-chan *Work) {
    for work := range workChan {
        go safelyDo(work)   // start the goroutine for that work
    }
}

func safelyDo(work *Work) {
    defer func() {
        if err := recover(); err != nil {
            log.Printf("Work failed with %s in %v", err, work)
        }
    }()
    do(work)
}
```

上边的代码，如果 `do(work)` 发生 panic，错误会被记录且协程会退出并释放，而其他协程不受影响。

因为 `recover` 总是返回 `nil`，除非直接在 `defer` 修饰的函数中调用，`defer` 修饰的代码可以调用那些自身可以使用 `panic` 和 `recover` 避免失败的库例程（库函数）。举例，`safelyDo()` 中 `defer` 修饰的函数可能在调用 `recover` 之前就调用了一个 `logging` 函数，`panicking` 状态不会影响 `logging` 代码的运行。因为加入了恢复模式，函数 `do`（以及它调用的任何东西）可以通过调用 `panic` 来摆脱不好的情况。但是恢复是在 `panicking` 的协程内部的：不能被另外一个协程恢复。

## 链接

* [目录](https://github.com/yangchuansheng/the-way-to-go_ZH_CN/tree/f30ab7d8c58f85840a0afb548024b93642b518d5/eBook/directory.md)
* 上一节：[通道，超时和计时器](/the-way-to-go-zh-cn/di-san-bu-fen-go-gao-ji-bian-cheng/14.0/14.5.md)
* 下一节：[对比新旧模型：任务和工作](https://github.com/yangchuansheng/the-way-to-go_ZH_CN/tree/f30ab7d8c58f85840a0afb548024b93642b518d5/eBook/14.7.md)


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