使用go http client Do方法时，httpResponse和错误是否可以同时为nil？

时间：2017-09-26 10:01:41

标签： http go

在official documentation以及几乎在网上其他地方都可以看到，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()

在http客户端上阅读有关方法的文档时，我无法理解是否可以同时接收resp和err nil ，如果我们考虑Do方法文档中的内容，似乎可以这样做：

  

请求Body，如果非nil，将被底层关闭   运输，即使出现错误。

     

出错时，可以忽略任何响应。一个非零的响应   只有当CheckRedirect失败时才会出现非零错误，即便如此   返回Response.Body已经关闭。

因此我的问题如下：

  1. 是否可以同时收到非零resp 和 err？
  2. 如果可能，并且在我的程序中，我最终收到了很多错误，并且return或panic在上面显示的//handle error段代码中，因此从未之后到达延迟，是否有可能从长远来看，我最终会有太多开放的车体，而运输工具无法关闭？

    3. 背景附录：

    我遇到的问题是，经过一段时间后，程序在stdErr上崩溃了以下大量的goroutine，并且在跟踪之后我最终得到一段似乎正常的代码，除非发生了一些不好的事情。遇到错误并且有一个响应没有延迟关闭，但由于官方文档说不要担心，问题必须在其他地方...... 

    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，如下面的评论中所示，但这个问题可能对其他人提出同样的问题很有用。

1 个答案:

答案 0 :(得分：2)

是的，显然，在一种情况下，它们都可以是非零的。从the source开始，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
        }

每次其他返回都返回响应和nil err，或者返回零响应和非零错误。
所以对于上面的问题：

  1. 是
  2. 不可能发生，因为身体和错误都是非零的唯一情况，身体已经关闭
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