net/http: recover veils some nil pointer deref crashes at server side, but that's the way of the net/http world #6943

mattn · 2013-12-13T00:34:06Z

But report.

Here is a blog post takeing benchmark. He did

  ab -n 1000 -c 100 http://127.0.0.1:8080

But sometimes go occur panic. below is a stacktrace.

...
21:01:13 go.1   | goroutine 1079 [select]:
21:01:13 go.1   | net/http.(*persistConn).roundTrip(0xc21056d900, 0xc2101add70,
0xc21056d900, 0x0, 0x0)
21:01:13 go.1   |      
/usr/local/Cellar/go/1.2/libexec/src/pkg/net/http/transport.go:879 +0x6d6
21:01:13 go.1   | net/http.(*Transport).RoundTrip(0xc210057200, 0xc2106e3a90, 0x1, 0x0,
0x0)
21:01:13 go.1   |      
/usr/local/Cellar/go/1.2/libexec/src/pkg/net/http/transport.go:187 +0x391
21:01:13 go.1   | net/http.send(0xc2106e3a90, 0x56c290, 0xc210057200, 0x0, 0x0, ...)
21:01:13 go.1   |       /usr/local/Cellar/go/1.2/libexec/src/pkg/net/http/client.go:168
+0x37f
21:01:13 go.1   | net/http.(*Client).send(0xc2106e74b0, 0xc2106e3a90, 0x16, 0x1,
0xc2101add60)
21:01:13 go.1   |       /usr/local/Cellar/go/1.2/libexec/src/pkg/net/http/client.go:100
+0xd9
21:01:13 go.1   | net/http.(*Client).doFollowingRedirects(0xc2106e74b0, 0xc2106e3a90,
0x2af1f8, 0x0, 0x0, ...)
21:01:13 go.1   |       /usr/local/Cellar/go/1.2/libexec/src/pkg/net/http/client.go:294
+0x671
21:01:13 go.1   | net/http.(*Client).Do(0xc2106e74b0, 0xc2106e3a90, 0x485dc0, 0x0, 0x0)
21:01:13 go.1   |       /usr/local/Cellar/go/1.2/libexec/src/pkg/net/http/client.go:129
+0x8f
21:01:13 go.1   | github.com/kentaro/delta.(*Handler).dispatchProxyRequest(0xc2100001f0,
0xc210036960, 0xc2106b34e0, 0xc2106a7840, 0xc2106abee0)
21:01:13 go.1   |       /Users/usr0600239/.go/src/github.com/kentaro/delta/handler.go:71
+0xb0
21:01:13 go.1   | created by github.com/kentaro/delta.(*Handler).ServeHTTP
21:01:13 go.1   |       /Users/usr0600239/.go/src/github.com/kentaro/delta/handler.go:29
+0x1fa
21:01:13 go.1   |
21:01:13 go.1   | goroutine 1078 [chan receive]:
21:01:13 go.1   | github.com/kentaro/delta.func·001()
21:01:13 go.1   |       /Users/usr0600239/.go/src/github.com/kentaro/delta/handler.go:38
+0x80
21:01:13 go.1   | created by github.com/kentaro/delta.(*Handler).ServeHTTP
21:01:13 go.1   |       /Users/usr0600239/.go/src/github.com/kentaro/delta/handler.go:52
+0x258
21:01:13 go.1   |
21:01:13 go.1   | goroutine 1076 [select]:
21:01:13 go.1   | exited with code 2
21:01:13 system | sending SIGTERM to all processes
21:01:13 go.1   | exited with code 0

And he says, around over 5000 requests, go doesn't return response.

mikioh · 2013-12-13T01:53:10Z

Comment 1:

Please use some debugger or other tool to tell us the detail of the issue. I just read
your friend's blog (in Japanese), it happens on OS X with Go 1.2, and now see a few bugs
in the code. For example, 
res, err := client.Do(proxyRequest)
if err != nil {
        log.Printf("HTTP Request Error: %s\n", err)
}
response, err := NewResponse(backend, res, elapsed) // this guy may touch a nil pointer
> go doesn't return response.
I believe that Go standard library reports resource exhaustion but the code ignores and
tries to continue a chicken race, in that case ulimit or launchctl would be a solution.

Status changed to Retracted.

mattn · 2013-12-13T02:34:05Z

Comment 3:

Do you mean code of delta?
https://github.com/kentaro/delta/blob/master/handler.go#L77-L90
if return err, the code doesn't refer res as nil. I guess.

mikioh · 2013-12-13T03:03:06Z

Comment 4:

Glad to hear it's fixed.

mikioh · 2013-12-13T03:07:52Z

Comment 5:

Also your friend may need to modify /etc/launchd.conf like:
% cat /etc/launchd.conf 
limit maxfiles 8192 8192

mattn · 2013-12-13T03:22:54Z

Comment 6:

Sure, but I can't understand why perl pass all requests.

mattn added the retracted label Dec 13, 2013

golang locked and limited conversation to collaborators Jun 25, 2016

gopherbot added the FrozenDueToAge label Jun 25, 2016

This issue was closed.

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net/http: recover veils some nil pointer deref crashes at server side, but that's the way of the net/http world #6943

net/http: recover veils some nil pointer deref crashes at server side, but that's the way of the net/http world #6943

mattn commented Dec 13, 2013

mikioh commented Dec 13, 2013

mattn commented Dec 13, 2013

mikioh commented Dec 13, 2013

mikioh commented Dec 13, 2013

mattn commented Dec 13, 2013

net/http: recover veils some nil pointer deref crashes at server side, but that's the way of the net/http world #6943

net/http: recover veils some nil pointer deref crashes at server side, but that's the way of the net/http world #6943

Comments

mattn commented Dec 13, 2013

mikioh commented Dec 13, 2013

mattn commented Dec 13, 2013

mikioh commented Dec 13, 2013

mikioh commented Dec 13, 2013

mattn commented Dec 13, 2013