英文:
Panic in Golang http.Client with high concurrent excecutions
问题
我正在创建一个基于golang的http服务器系统，它将根据每个请求向另一个API发送多个请求。
例如：
curl localhost:8080/users?ids=1,2,3,4
将同时向以下地址发送多个GET请求：
api.com/user/1
api.com/user/2
api.com/user/3
api.com/user/4
我遇到了一个问题，当http.Client同时处理大量请求时（例如使用AB工具以4个并发连接访问localhost:8080/users?ids=1,2,3,4...40，或者在浏览器中频繁刷新），会导致panic错误。
问题似乎出现在以下代码行（第159行）：
resp, _ := client.Do(req)
我的代码在这里（不是很长...180行）：
http://play.golang.org/p/olibNz2n1Z
panic错误信息如下：
goroutine 5 [select]:
net/http.(*persistConn).roundTrip(0xc210058f80, 0xc21000a720, 0xc210058f80, 0x0, 0x0)
/usr/local/go/src/pkg/net/http/transport.go:879 +0x6d6
net/http.(*Transport).RoundTrip(0xc210058280, 0xc21005b1a0, 0x1, 0x0, 0x0)
/usr/local/go/src/pkg/net/http/transport.go:187 +0x391
net/http.send(0xc21005b1a0, 0x590290, 0xc210058280, 0x0, 0x0, ...)
/usr/local/go/src/pkg/net/http/client.go:168 +0x37f
net/http.(*Client).send(0xc21001e960, 0xc21005b1a0, 0x28, 0xc21001ec30, 0xc21005f570)
/usr/local/go/src/pkg/net/http/client.go:100 +0xd9
net/http.(*Client).doFollowingRedirects(0xc21001e960, 0xc21005b1a0, 0x2ab298, 0x0, 0x0, ...)
/usr/local/go/src/pkg/net/http/client.go:294 +0x671
net/http.(*Client).Do(0xc21001e960, 0xc21005b1a0, 0xa, 0x0, 0x0)
/usr/local/go/src/pkg/net/http/client.go:129 +0x8f
main.buscarRecurso(0xc21000a650, 0xb, 0xc2100526c0)
/Users/fscasserra/Documents/workspace/Luna/multiget-api/multiget.go:159 +0x131
created by main.obtenerRecursos
/Users/fscasserra/Documents/workspace/Luna/multiget-api/multiget.go:106 +0x197
有人可以帮助我吗？
最好的祝愿，
Fer
英文:
I am creating a system which is a http server in golang that will perform several request to another API based in every request that come to it.
e.g
curl localhost:8080/users?ids=1,2,3,4
will perform several concurrent gets to:
api.com/user/1
api.com/user/2
api.com/user/3
api.com/user/4
I am having a problem, the http.Client is getting my a panic, when it has a heavy concurrent requests (if I hit localhost:8080/users?ids=1,2,3,4.....40 with AB with 4 concurrent, or hitting refresh in my browser)
The proglem appears to be with the sentence (line 159)
resp, _ := client.Do(req)
My code is here (Not so large... 180 lines):
http://play.golang.org/p/olibNz2n1Z
The panic error is this one:
goroutine 5 [select]:
net/http.(*persistConn).roundTrip(0xc210058f80, 0xc21000a720, 0xc210058f80, 0x0, 0x0)
/usr/local/go/src/pkg/net/http/transport.go:879 +0x6d6
net/http.(*Transport).RoundTrip(0xc210058280, 0xc21005b1a0, 0x1, 0x0, 0x0)
/usr/local/go/src/pkg/net/http/transport.go:187 +0x391
net/http.send(0xc21005b1a0, 0x590290, 0xc210058280, 0x0, 0x0, ...)
/usr/local/go/src/pkg/net/http/client.go:168 +0x37f
net/http.(*Client).send(0xc21001e960, 0xc21005b1a0, 0x28, 0xc21001ec30, 0xc21005f570)
/usr/local/go/src/pkg/net/http/client.go:100 +0xd9
net/http.(*Client).doFollowingRedirects(0xc21001e960, 0xc21005b1a0, 0x2ab298, 0x0, 0x0, ...)
/usr/local/go/src/pkg/net/http/client.go:294 +0x671
net/http.(*Client).Do(0xc21001e960, 0xc21005b1a0, 0xa, 0x0, 0x0)
/usr/local/go/src/pkg/net/http/client.go:129 +0x8f
main.buscarRecurso(0xc21000a650, 0xb, 0xc2100526c0)
/Users/fscasserra/Documents/workspace/Luna/multiget-api/multiget.go:159 +0x131
created by main.obtenerRecursos
/Users/fscasserra/Documents/workspace/Luna/multiget-api/multiget.go:106 +0x197
Can anyone help me?
Best regards,
Fer
答案1
得分: 2
我会将钱押在对空的resp.Body调用Close()引发恐慌上。
始终检查错误！
一般来说，如果一个函数返回一个值和一个错误，那么在出现非空错误的情况下，响应值可能无法使用。任何对此的例外情况都应该有很好的文档说明。
英文:
I will put money on the panic coming from calling Close() on a nil resp.Body.
Always check your errors!
In general, if a function returns a value and an error, the response value may not be usable in the case of a non-nil error. Any exceptions to this should be well documented.
通过集体智慧和协作来改善编程学习和解决问题的方式。致力于成为全球开发者共同参与的知识库，让每个人都能够通过互相帮助和分享经验来进步。
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