http - 使用go http client Do方法时，httpResponse和error不能同时为nil吗？

标签 http go

在 official documentation 中可见以及几乎其他网上的任何地方，处理 http 客户端错误的常见模式如下:

req, err := http.NewRequest("GET", "http://example.com", nil)
req.Header.Add("If-None-Match", `W/"wyzzy"`)
resp, err := client.Do(req)
if err != nil {
    // handle error
}
defer resp.Body.Close()

阅读有关 http 客户端方法的文档，我无法理解是否可以同时接收 resp和 err 不是 nil，如果我们考虑一下 Do 方法文档中写的内容，这似乎是可能的:

The request Body, if non-nil, will be closed by the underlying Transport, even on errors.

On error, any Response can be ignored. A non-nil Response with a non-nil error only occurs when CheckRedirect fails, and even then the returned Response.Body is already closed.

因此我的问题如下:

  1. 是否有可能收到非零resp 和 err同时？
  2. 如果可能的话，在我的程序中我最终会收到很多错误，我 return或 panic在//handle error上面显示的一段代码，因此之后永远不会立即到达延迟，从长远来看，是否有可能我最终有太多开放的 body 而传输无法关闭？

上下文附录:

我遇到的问题是，过了一会儿，程序崩溃了，在 stdErr 上出现了以下 goroutines 的大打印，并且跟踪跟踪我最终得到一段看起来正常的代码，除非如果遇到错误，并且有一个 responseBody 不会对其进行延迟关闭，但由于官方文档说不用担心，问题一定出在其他地方......

Stderr logs
  Display timestamps
 net/http.(*persistConn).readLoop(0xc4244e0240)
    /usr/local/go/src/net/http/transport.go:1474 +0x196
created by net/http.(*Transport).dialConn
    /usr/local/go/src/net/http/transport.go:1117 +0xa35

goroutine 194055 [select, 2 minutes]:
net/http.(*persistConn).readLoop(0xc42421ec60)
    /usr/local/go/src/net/http/transport.go:1599 +0x9ec
created by net/http.(*Transport).dialConn
    /usr/local/go/src/net/http/transport.go:1117 +0xa35

goroutine 215944 [IO wait]:
net.runtime_pollWait(0x7f63736f0628, 0x72, 0x21b)
    /usr/local/go/src/runtime/netpoll.go:164 +0x59
net.(*pollDesc).wait(0xc420963568, 0x72, 0xa85c40, 0xa81350)
    /usr/local/go/src/net/fd_poll_runtime.go:75 +0x38
net.(*pollDesc).waitRead(0xc420963568, 0xc422289000, 0x1000)
    /usr/local/go/src/net/fd_poll_runtime.go:80 +0x34
net.(*netFD).Read(0xc420963500, 0xc422289000, 0x1000, 0x1000, 0x0, 0xa85c40, 0xa81350)
    /usr/local/go/src/net/fd_unix.go:250 +0x1b7
net.(*conn).Read(0xc42025bbb8, 0xc422289000, 0x1000, 0x1000, 0x0, 0x0, 0x0)
    /usr/local/go/src/net/net.go:181 +0x70
net/http.(*persistConn).Read(0xc4217af8c0, 0xc422289000, 0x1000, 0x1000, 0xc420b33400, 0x8b61a3, 0xc423dd6b80)
    /usr/local/go/src/net/http/transport.go:1316 +0x14b
bufio.(*Reader).fill(0xc421af0060)
    /usr/local/go/src/bufio/bufio.go:97 +0x117
bufio.(*Reader).Peek(0xc421af0060, 0x1, 0xc421af01e0, 0xc420536c80, 0xc420b17e00, 0x60, 0xc420536c60)
    /usr/local/go/src/bufio/bufio.go:129 +0x67
net/http.(*persistConn).readLoop(0xc4217af8c0)
    /usr/local/go/src/net/http/transport.go:1474 +0x196
created by net/http.(*Transport).dialConn
    /usr/local/go/src/net/http/transport.go:1117 +0xa35

goroutine 199855 [select, 1 minutes]:
net/http.(*persistConn).writeLoop(0xc421db1320)
    /usr/local/go/src/net/http/transport.go:1704 +0x43a
created by net/http.(*Transport).dialConn
    /usr/local/go/src/net/http/transport.go:1118 +0xa5a

goroutine 198707 [select, 1 minutes]:
net/http.(*persistConn).readLoop(0xc4236ea000)
    /usr/local/go/src/net/http/transport.go:1599 +0x9ec
created by net/http.(*Transport).dialConn
    /usr/local/go/src/net/http/transport.go:1117 +0xa35

goroutine 192577 [select, 2 minutes]:
net/http.(*persistConn).readLoop(0xc424a8fc20)
    /usr/local/go/src/net/http/transport.go:1599 +0x9ec
created by net/http.(*Transport).dialConn
    /usr/local/go/src/net/http/transport.go:1117 +0xa35

goroutine 213681 [select]:
net/http.(*persistConn).writeLoop(0xc42455e6c0)
    /usr/local/go/src/net/http/transport.go:1704 +0x43a
created by net/http.(*Transport).dialConn
    /usr/local/go/src/net/http/transport.go:1118 +0xa5a

goroutine 190222 [select, 2 minutes]:
net/http.(*persistConn).writeLoop(0xc4238617a0)
    /usr/local/go/src/net/http/transport.go:1704 +0x43a
created by net/http.(*Transport).dialConn
    /usr/local/go/src/net/http/transport.go:1118 +0xa5a

goroutine 208970 [select, 1 minutes]:
net/http.(*persistConn).writeLoop(0xc4234530e0)
    /usr/local/go/src/net/http/transport.go:1704 +0x43a
created by net/http.(*Transport).dialConn
    /usr/local/go/src/net/http/transport.go:1118 +0xa5a

goroutine 219699 [select]:
net/http.(*persistConn).writeLoop(0xc42155cb40)
    /usr/local/go/src/net/http/transport.go:1704 +0x43a
created by net/http.(*Transport).dialConn
    /usr/local/go/src/net/http/transport.go:1118 +0xa5a

goroutine 221664 [select]:
net/http.setRequestCancel.func3(0x0, 0xc4231af680, 0xc423657000, 0xc4214aeecc, 0xc422f926c0)
    /usr/local/go/src/net/http/client.go:320 +0x17c
created by net/http.setRequestCancel
    /usr/local/go/src/net/http/client.go:330 +0x287

goroutine 220550 [select]:
net/http.(*persistConn).readLoop(0xc4218f0c60)
    /usr/local/go/src/net/http/transport.go:1599 +0x9ec
created by net/http.(*Transport).dialConn
    /usr/local/go/src/net/http/transport.go:1117 +0xa35

goroutine 216169 [IO wait]:
net.runtime_pollWait(0x7f6373700fb0, 0x72, 0x221)
    /usr/local/go/src/runtime/netpoll.go:164 +0x59
net.(*pollDesc).wait(0xc4212fdb18, 0x72, 0xa85c40, 0xa81350)
    /usr/local/go/src/net/fd_poll_runtime.go:75 +0x38
net.(*pollDesc).waitRead(0xc4212fdb18, 0xc42393c000, 0x1000)
    /usr/local/go/src/net/fd_poll_runtime.go:80 +0x34
net.(*netFD).Read(0xc4212fdab0, 0xc42393c000, 0x1000, 0x1000, 0x0, 0xa85c40, 0xa81350)
    /usr/local/go/src/net/fd_unix.go:250 +0x1b7
net.(*conn).Read(0xc42300aa38, 0xc42393c000, 0x1000, 0x1000, 0x0, 0x0, 0x0)
    /usr/local/go/src/net/net.go:181 +0x70
net/http.(*persistConn).Read(0xc422102c60, 0xc42393c000, 0x1000, 0x1000, 0xc423d30820, 0xc42002a800, 0xc424422b80)
    /usr/local/go/src/net/http/transport.go:1316 +0x14b
bufio.(*Reader).fill(0xc4220598c0)
    /usr/local/go/src/bufio/bufio.go:97 +0x117
bufio.(*Reader).Peek(0xc4220598c0, 0x1, 0xc422059a40, 0xc420535c80, 0xc422059700, 0x60, 0xc420535c60)
    /usr/local/go/src/bufio/bufio.go:129 +0x67
net/http.(*persistConn).readLoop(0xc422102c60)
    /usr/local/go/src/net/http/transport.go:1474 +0x196
created by net/http.(*Transport).dialConn
    /usr/local/go/src/net/http/transport.go:1117 +0xa35

goroutine 213706 [select]:
net/http.(*persistConn).writeLoop(0xc42321d200)
    /usr/local/go/src/net/http/transport.go:1704 +0x43a
created by net/http.(*Transport).dialConn
    /usr/local/go/src/net/http/transport.go:1118 +0xa5a

goroutine 214335 [select]:
net/http.(*persistConn).writeLoop(0xc4230d7560)
    /usr/local/go/src/net/http/transport.go:1704 +0x43a
created by net/http.(*Transport).dialConn
    /usr/local/go/src/net/http/transport.go:1118 +0xa5a

goroutine 221651 [IO wait]:
net.runtime_pollWait(0x7f63736eff38, 0x72, 0x254)
    /usr/local/go/src/runtime/netpoll.go:164 +0x59
net.(*pollDesc).wait(0xc422449b18, 0x72, 0xa85c40, 0xa81350)
    /usr/local/go/src/net/fd_poll_runtime.go:75 +0x38
net.(*pollDesc).waitRead(0xc422449b18, 0xc423d93000, 0x1000)
    /usr/local/go/src/net/fd_poll_runtime.go:80 +0x34
net.(*netFD).Read(0xc422449ab0, 0xc423d93000, 0x1000, 0x1000, 0x0, 0xa85c40, 0xa81350)
    /usr/local/go/src/net/fd_unix.go:250 +0x1b7
net.(*conn).Read(0xc421eb21b8, 0xc423d93000, 0x1000, 0x1000, 0x0, 0x0, 0x0)
    /usr/local/go/src/net/net.go:181 +0x70
net/http.(*persistConn).Read(0xc422e5b440, 0xc423d93000, 0x1000, 0x1000, 0x8cc888, 0x0, 0xc42347bb80)
    /usr/local/go/src/net/http/transport.go:1316 +0x14b
bufio.(*Reader).fill(0xc422f2c960)
    /usr/local/go/src/bufio/bufio.go:97 +0x117
bufio.(*Reader).Peek(0xc422f2c960, 0x1, 0xc422f2d6e0, 0xc420b8ec80, 0xc42180ff00, 0x60, 0xc420b8ec60)
    /usr/local/go/src/bufio/bufio.go:129 +0x67
net/http.(*persistConn).readLoop(0xc422e5b440)
    /usr/local/go/src/net/http/transport.go:1474 +0x196
created by net/http.(*Transport).dialConn
    /usr/local/go/src/net/http/transport.go:1117 +0xa35

goroutine 221670 [IO wait]:
net.runtime_pollWait(0x7f63736ff7b0, 0x72, 0x259)
    /usr/local/go/src/runtime/netpoll.go:164 +0x59
net.(*pollDesc).wait(0xc422449b88, 0x72, 0xa85c40, 0xa81350)
    /usr/local/go/src/net/fd_poll_runtime.go:75 +0x38
net.(*pollDesc).waitRead(0xc422449b88, 0xc423f28000, 0x1000)
    /usr/local/go/src/net/fd_poll_runtime.go:80 +0x34
net.(*netFD).Read(0xc422449b20, 0xc423f28000, 0x1000, 0x1000, 0x0, 0xa85c40, 0xa81350)
    /usr/local/go/src/net/fd_unix.go:250 +0x1b7
net.(*conn).Read(0xc423eac3c8, 0xc423f28000, 0x1000, 0x1000, 0x0, 0x0, 0x0)
    /usr/local/go/src/net/net.go:181 +0x70
net/http.(*persistConn).Read(0xc4235930e0, 0xc423f28000, 0x1000, 0x1000, 0xa82dc0, 0xc42000e0b0, 0xc423be7b80)
    /usr/local/go/src/net/http/transport.go:1316 +0x14b
bufio.(*Reader).fill(0xc422bb70e0)
    /usr/local/go/src/bufio/bufio.go:97 +0x117
bufio.(*Reader).Peek(0xc422bb70e0, 0x1, 0xc422bb7320, 0xc424191480, 0xc4237a4820, 0x0, 0xc422ac9138)
    /usr/local/go/src/bufio/bufio.go:129 +0x67
net/http.(*persistConn).readLoop(0xc4235930e0)
    /usr/local/go/src/net/http/transport.go:1474 +0x196
created by net/http.(*Transport).dialConn
    /usr/local/go/src/net/http/transport.go:1117 +0xa35

goroutine 213543 [select]:
net/http.(*persistConn).readLoop(0xc424795c20)
    /usr/local/go/src/net/http/transport.go:1599 +0x9ec
created by net/http.(*Transport).dialConn
    /usr/local/go/src/net/http/transport.go:1117 +0xa35

goroutine 220529 [select]:
net/http.(*persistConn).roundTrip(0xc4215fd680, 0xc4212c5c80, 0x0, 0x0, 0x0)
    /usr/local/go/src/net/http/transport.go:1898 +0x974
net/http.(*Transport).RoundTrip(0xc420847b30, 0xc421248800, 0xc420847b30, 0xed15b2cf4, 0x16cd81f7)
    /usr/local/go/src/net/http/transport.go:391 +0x74c
net/http.send(0xc421248700, 0xa84080, 0xc420847b30, 0xed15b2cf4, 0x16cd81f7, 0xab7060, 0x0, 0x8, 0xc4213a2a80, 0x40f258)
    /usr/local/go/src/net/http/client.go:249 +0x162
net/http.(*Client).send(0xc42075ed20, 0xc421248700, 0xed15b2cf4, 0x16cd81f7, 0xab7060, 0xc4213a2a80, 0x0, 0x1, 0x4084fe)
    /usr/local/go/src/net/http/client.go:173 +0x108
net/http.(*Client).Do(0xc42075ed20, 0xc421248700, 0xa, 0x8b359b, 0x5)
    /usr/local/go/src/net/http/client.go:595 +0x254
github.com/myCompanyName/gojsonrpc.(*Client).sendJsonRequest(0xc42078c6e0, 0xc4215fd320, 0xbb, 0x11a, 0x0, 0x0, 0x0, 0x0, 0x0)
    /home/ubuntu/go/src/github.com/myCompanyName/gojsonrpc/client.go:45 +0x2f2
github.com/myCompanyName/gojsonrpc.(*Client).Run(0xc42078c6e0, 0x8be6b2, 0x1d, 0x838780, 0xc420789ce0, 0x7fb2e0, 0xc4212c5b40, 0x1, 0xe)
    /home/ubuntu/go/src/github.com/myCompanyName/gojsonrpc/client.go:72 +0x219
github.com/myCompanyName/app/connectors/vendor.(*Connector).ReadStatus(0xc42078aa30, 0xc4212c5a60, 0xd, 0xc4212c5a6e, 0x7, 0xc4212c59c0, 0x1d, 0x0, 0x0, 0x0, ...)
    /home/ubuntu/go/src/github.com/myCompanyName/app/connectors/vendor/tickets.go:52 +0x386
github.com/myCompanyName/app/obscuredPkgName/connabslayer.(*ConnAbsLayer).ReadMetrics(0xc42075ac40, 0xc4212c5a60, 0x15, 0xc4212c59c0, 0x1d, 0xc42121eb30, 0xf)
    /home/ubuntu/go/src/github.com/myCompanyName/app/obscuredPkgName/connabslayer/connector_abstraction_layer.go:145 +0xdc
github.com/myCompanyName/app/obscuredPkgName/updater/plugins.(*UpdaterPlugin).SyncPluggedData(0xc42078c820, 0xc4208b9ef0, 0x28, 0xf)
    /home/ubuntu/go/src/github.com/myCompanyName/app/obscuredPkgName/updater/plugins/vendor_plugin.go:69 +0x1e1
github.com/myCompanyName/app/obscuredPkgName/updater.(*Updater).syncData.func1(0xc420763a00, 0xc4208b9ef0, 0x28, 0xc4201824f0, 0xf)
    /home/ubuntu/go/src/github.com/myCompanyName/app/obscuredPkgName/updater/updater.go:127 +0xf6
created by github.com/myCompanyName/app/obscuredPkgName/updater.(*Updater).syncData
    /home/ubuntu/go/src/github.com/myCompanyName/app/obscuredPkgName/updater/updater.go:131 +0x17b

// AND SO ON

解决方案:

问题出在其他地方，如以下评论所示，但该问题可能对其他提出相同问题的人有用。

最佳答案

是的，显然，在一种情况下它们都可以是非零。来自 the source ，我们看到:

        if err != nil {
            // Special case for Go 1 compatibility: return both the response
            // and an error if the CheckRedirect function failed.
            // See https://golang.org/issue/3795
            // The resp.Body has already been closed.
            ue := uerr(err)
            ue.(*url.Error).URL = loc
            return resp, ue
        }

每个其他返回要么返回一个响应和 nil err，要么返回一个 nil 响应和非 nil 错误。
所以对于上面的问题:

  1. 是
  2. 不可能发生，对于主体和错误都非零的唯一情况，主体已经关闭

关于http - 使用go http client Do方法时，httpResponse和error不能同时为nil吗？，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/46423385/

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