net/http: panic: runtime error: slice bounds out of range

[sebcat]

Hello,

I experience a panic intermittently when using a Transport concurrently against certain URLs. It happens when I read the response body using an io.LimitedReader with ioutil.ReadAll.

I've isolated the problem from a larger application and I would like to share the code for issue reproduction privately, as I am only able to reproduce it for certain URLs and I don't want those URLs in the issue tracker.

I've tested the example with go 1.4.2 and go 1.5 on a couple of different machines. If I run the example locally, I may have to run it a few times before experiencing a panic. If I run the example on a remote machine with different network/hardware/linux distribution that I have access to, it occurs 100% of the time. I don't know why.

Complete stack trace:

panic: runtime error: slice bounds out of range [recovered]
    panic: runtime error: slice bounds out of range

goroutine 8 [running]:
io/ioutil.readAll.func1(0xc820040db0)
    /home/sebastian/go/src/io/ioutil/ioutil.go:30 +0x11e
bufio.(*Reader).ReadSlice(0xc820021c20, 0xa, 0x0, 0x0, 0x0, 0x0, 0x0)
    /home/sebastian/go/src/bufio/bufio.go:306 +0x229
net/http/internal.readLine(0xc820021c20, 0x0, 0x0, 0x0, 0x0, 0x0)
    /home/sebastian/go/src/net/http/internal/chunked.go:110 +0x4b
net/http/internal.(*chunkedReader).beginChunk(0xc82028e210)
    /home/sebastian/go/src/net/http/internal/chunked.go:47 +0x39
net/http/internal.(*chunkedReader).Read(0xc82028e210, 0xc8201f8600, 0x200, 0x200, 0x0, 0x0, 0x0)
    /home/sebastian/go/src/net/http/internal/chunked.go:77 +0xb7
net/http.(*body).readLocked(0xc8200a9600, 0xc8201f8600, 0x200, 0x200, 0x0, 0x0, 0x0)
    /home/sebastian/go/src/net/http/transfer.go:632 +0x98
net/http.(*body).Read(0xc8200a9600, 0xc8201f8600, 0x200, 0x200, 0x0, 0x0, 0x0)
    /home/sebastian/go/src/net/http/transfer.go:624 +0x110
net/http.(*bodyEOFSignal).Read(0xc8200a9640, 0xc8201f8600, 0x200, 0x200, 0x0, 0x0, 0x0)
    /home/sebastian/go/src/net/http/transport.go:1296 +0x26a
io.(*LimitedReader).Read(0xc820221280, 0xc8201f8600, 0x200, 0x200, 0x200, 0x0, 0x0)
    /home/sebastian/go/src/io/io.go:427 +0xbd
bytes.(*Buffer).ReadFrom(0xc820040d08, 0x7f9bbcb26b68, 0xc820221280, 0x0, 0x0, 0x0)
    /home/sebastian/go/src/bytes/buffer.go:173 +0x23f
io/ioutil.readAll(0x7f9bbcb26b68, 0xc820221280, 0x200, 0x0, 0x0, 0x0, 0x0, 0x0)
    /home/sebastian/go/src/io/ioutil/ioutil.go:33 +0x154
io/ioutil.ReadAll(0x7f9bbcb26b68, 0xc820221280, 0x0, 0x0, 0x0, 0x0, 0x0)
    /home/sebastian/go/src/io/ioutil/ioutil.go:42 +0x51
main.main.func1(0xc820020120, 0xc82001c1b0, 0xc82000ad40)
    /home/sebastian/urls.go:75 +0x4d1
created by main.main
    /home/sebastian/urls.go:83 +0x1ff

goroutine 1 [chan send]:
main.main()
    /home/sebastian/urls.go:87 +0x2c3

goroutine 17 [syscall, locked to thread]:
runtime.goexit()
    /home/sebastian/go/src/runtime/asm_amd64.s:1696 +0x1

goroutine 5 [select]:
net/http.(*persistConn).roundTrip(0xc820118840, 0xc820335290, 0x0, 0x0, 0x0)
    /home/sebastian/go/src/net/http/transport.go:1164 +0xb0d
net/http.(*Transport).RoundTrip(0xc82001c1b0, 0xc8200ad500, 0x737ef0, 0x0, 0x0)
    /home/sebastian/go/src/net/http/transport.go:235 +0x530
main.main.func1(0xc820020120, 0xc82001c1b0, 0xc82000ad40)
    /home/sebastian/urls.go:66 +0x1e2
created by main.main
    /home/sebastian/urls.go:83 +0x1ff

goroutine 6 [select]:
net/http.(*persistConn).roundTrip(0xc8200b0000, 0xc8200d0080, 0x0, 0x0, 0x0)
    /home/sebastian/go/src/net/http/transport.go:1164 +0xb0d
net/http.(*Transport).RoundTrip(0xc82001c1b0, 0xc8200ce0e0, 0x737f30, 0x0, 0x0)
    /home/sebastian/go/src/net/http/transport.go:235 +0x530
main.main.func1(0xc820020120, 0xc82001c1b0, 0xc82000ad40)
    /home/sebastian/urls.go:66 +0x1e2
created by main.main
    /home/sebastian/urls.go:83 +0x1ff

goroutine 7 [select]:
net/http.(*persistConn).roundTrip(0xc8200de000, 0xc8202e4190, 0x0, 0x0, 0x0)
    /home/sebastian/go/src/net/http/transport.go:1164 +0xb0d
net/http.(*Transport).RoundTrip(0xc82001c1b0, 0xc82010e7e0, 0x7431e0, 0x0, 0x0)
    /home/sebastian/go/src/net/http/transport.go:235 +0x530
main.main.func1(0xc820020120, 0xc82001c1b0, 0xc82000ad40)
    /home/sebastian/urls.go:66 +0x1e2
created by main.main
    /home/sebastian/urls.go:83 +0x1ff

goroutine 9 [select]:
net/http.(*persistConn).roundTrip(0xc8200de210, 0xc8200cc140, 0x0, 0x0, 0x0)
    /home/sebastian/go/src/net/http/transport.go:1164 +0xb0d
net/http.(*Transport).RoundTrip(0xc82001c1b0, 0xc8200c8380, 0x743240, 0x0, 0x0)
    /home/sebastian/go/src/net/http/transport.go:235 +0x530
main.main.func1(0xc820020120, 0xc82001c1b0, 0xc82000ad40)
    /home/sebastian/urls.go:66 +0x1e2
created by main.main
    /home/sebastian/urls.go:83 +0x1ff

goroutine 10 [select]:
net/http.(*persistConn).roundTrip(0xc8200de160, 0xc8202683b0, 0x0, 0x0, 0x0)
    /home/sebastian/go/src/net/http/transport.go:1164 +0xb0d
net/http.(*Transport).RoundTrip(0xc82001c1b0, 0xc8200acfc0, 0x759440, 0x0, 0x0)
    /home/sebastian/go/src/net/http/transport.go:235 +0x530
main.main.func1(0xc820020120, 0xc82001c1b0, 0xc82000ad40)
    /home/sebastian/urls.go:66 +0x1e2
created by main.main
    /home/sebastian/urls.go:83 +0x1ff

goroutine 11 [runnable]:
syscall.Syscall(0x0, 0x4, 0xc82015ab68, 0x1498, 0x1498, 0x1498, 0x0)
    /home/sebastian/go/src/syscall/asm_linux_amd64.s:18 +0x5
syscall.read(0x4, 0xc82015ab68, 0x1498, 0x1498, 0x72, 0x0, 0x0)
    /home/sebastian/go/src/syscall/zsyscall_linux_amd64.go:783 +0x5f
syscall.Read(0x4, 0xc82015ab68, 0x1498, 0x1498, 0xffffffffffffff01, 0x0, 0x0)
    /home/sebastian/go/src/syscall/syscall_unix.go:160 +0x4d
net.(*netFD).Read(0xc8200180e0, 0xc82015ab68, 0x1498, 0x1498, 0x0, 0x0, 0x0)
    /home/sebastian/go/src/net/fd_unix.go:228 +0x18b
net.(*conn).Read(0xc820120000, 0xc82015ab68, 0x1498, 0x1498, 0x0, 0x0, 0x0)
    /home/sebastian/go/src/net/net.go:172 +0xe4
crypto/tls.(*block).readFromUntil(0xc8200ca3c0, 0x7f9bb9a6bfc0, 0xc820120000, 0x1f5d, 0x0, 0x0)
    /home/sebastian/go/src/crypto/tls/conn.go:455 +0xcc
crypto/tls.(*Conn).readRecord(0xc820124000, 0x77fa17, 0x0, 0x0)
    /home/sebastian/go/src/crypto/tls/conn.go:583 +0xccf
crypto/tls.(*Conn).Read(0xc820124000, 0xc82040998f, 0x2191, 0x2471, 0x0, 0x0, 0x0)
    /home/sebastian/go/src/crypto/tls/conn.go:901 +0x167
net/http.noteEOFReader.Read(0x7f9bb9a2b090, 0xc820124000, 0xc8200dc268, 0xc82040998f, 0x2191, 0x2471, 0x1f40, 0x0, 0x0)
    /home/sebastian/go/src/net/http/transport.go:1370 +0x67
net/http.(*noteEOFReader).Read(0xc8200da460, 0xc82040998f, 0x2191, 0x2471, 0x1f40, 0x0, 0x0)
    <autogenerated>:126 +0xd0
bufio.(*Reader).Read(0xc8200d2e40, 0xc82040998f, 0x2191, 0x2471, 0x1f40, 0x0, 0x0)
    /home/sebastian/go/src/bufio/bufio.go:197 +0x126
io.(*LimitedReader).Read(0xc82033a860, 0xc82040998f, 0x2191, 0x2471, 0xc820151a88, 0x0, 0x0)
    /home/sebastian/go/src/io/io.go:427 +0xbd
net/http.(*body).readLocked(0xc82025b240, 0xc82040998f, 0x2471, 0x2471, 0xc800000000, 0x0, 0x0)
    /home/sebastian/go/src/net/http/transfer.go:632 +0x98
net/http.(*body).Read(0xc82025b240, 0xc82040998f, 0x2471, 0x2471, 0x0, 0x0, 0x0)
    /home/sebastian/go/src/net/http/transfer.go:624 +0x110
net/http.(*bodyEOFSignal).Read(0xc82025b280, 0xc82040998f, 0x2471, 0x2471, 0x0, 0x0, 0x0)
    /home/sebastian/go/src/net/http/transport.go:1296 +0x26a
io.(*LimitedReader).Read(0xc82033a8c0, 0xc82040998f, 0x2471, 0x2471, 0x1f40, 0x0, 0x0)
    /home/sebastian/go/src/io/io.go:427 +0xbd
bytes.(*Buffer).ReadFrom(0xc820151cf8, 0x7f9bbcb26b68, 0xc82033a8c0, 0xd98f, 0x0, 0x0)
    /home/sebastian/go/src/bytes/buffer.go:173 +0x23f
io/ioutil.readAll(0x7f9bbcb26b68, 0xc82033a8c0, 0x200, 0x0, 0x0, 0x0, 0x0, 0x0)
    /home/sebastian/go/src/io/ioutil/ioutil.go:33 +0x154
io/ioutil.ReadAll(0x7f9bbcb26b68, 0xc82033a8c0, 0x0, 0x0, 0x0, 0x0, 0x0)
    /home/sebastian/go/src/io/ioutil/ioutil.go:42 +0x51
main.main.func1(0xc820020120, 0xc82001c1b0, 0xc82000ad40)
    /home/sebastian/urls.go:75 +0x4d1
created by main.main
    /home/sebastian/urls.go:83 +0x1ff

goroutine 12 [select]:
net/http.(*persistConn).roundTrip(0xc8200b13f0, 0xc8203351d0, 0x0, 0x0, 0x0)
    /home/sebastian/go/src/net/http/transport.go:1164 +0xb0d
net/http.(*Transport).RoundTrip(0xc82001c1b0, 0xc8200ad420, 0x737ed0, 0x0, 0x0)
    /home/sebastian/go/src/net/http/transport.go:235 +0x530
main.main.func1(0xc820020120, 0xc82001c1b0, 0xc82000ad40)
    /home/sebastian/urls.go:66 +0x1e2
created by main.main
    /home/sebastian/urls.go:83 +0x1ff

goroutine 13 [select]:
net/http.(*persistConn).roundTrip(0xc8200b14a0, 0xc8202e4b40, 0x0, 0x0, 0x0)
    /home/sebastian/go/src/net/http/transport.go:1164 +0xb0d
net/http.(*Transport).RoundTrip(0xc82001c1b0, 0xc82010e9a0, 0x743180, 0x0, 0x0)
    /home/sebastian/go/src/net/http/transport.go:235 +0x530
main.main.func1(0xc820020120, 0xc82001c1b0, 0xc82000ad40)
    /home/sebastian/urls.go:66 +0x1e2
created by main.main
    /home/sebastian/urls.go:83 +0x1ff

goroutine 14 [runnable]:
io.(*LimitedReader).Read(0xc820281360, 0xc82041be00, 0x10000, 0x10000, 0x4b7, 0x0, 0x0)
    /home/sebastian/go/src/io/io.go:420
bytes.(*Buffer).ReadFrom(0xc820055cf8, 0x7f9bbcb26b68, 0xc820281360, 0xfe00, 0x0, 0x0)
    /home/sebastian/go/src/bytes/buffer.go:173 +0x23f
io/ioutil.readAll(0x7f9bbcb26b68, 0xc820281360, 0x200, 0x0, 0x0, 0x0, 0x0, 0x0)
    /home/sebastian/go/src/io/ioutil/ioutil.go:33 +0x154
io/ioutil.ReadAll(0x7f9bbcb26b68, 0xc820281360, 0x0, 0x0, 0x0, 0x0, 0x0)
    /home/sebastian/go/src/io/ioutil/ioutil.go:42 +0x51
main.main.func1(0xc820020120, 0xc82001c1b0, 0xc82000ad40)
    /home/sebastian/urls.go:75 +0x4d1
created by main.main
    /home/sebastian/urls.go:83 +0x1ff

goroutine 43 [IO wait]:
net.runtime_pollWait(0x7f9bb9a6bf00, 0x72, 0xc82000a270)
    /home/sebastian/go/src/runtime/netpoll.go:157 +0x60
net.(*pollDesc).Wait(0xc82011c060, 0x72, 0x0, 0x0)
    /home/sebastian/go/src/net/fd_poll_runtime.go:73 +0x3a
net.(*pollDesc).WaitRead(0xc82011c060, 0x0, 0x0)
    /home/sebastian/go/src/net/fd_poll_runtime.go:78 +0x36
net.(*netFD).Read(0xc82011c000, 0xc8202f4000, 0x2000, 0x2000, 0x0, 0x7f9bbcb22168, 0xc82000a270)
    /home/sebastian/go/src/net/fd_unix.go:232 +0x23a
net.(*conn).Read(0xc820132000, 0xc8202f4000, 0x2000, 0x2000, 0x0, 0x0, 0x0)
    /home/sebastian/go/src/net/net.go:172 +0xe4
crypto/tls.(*block).readFromUntil(0xc82028e4e0, 0x7f9bb9a6bfc0, 0xc820132000, 0x5, 0x0, 0x0)
    /home/sebastian/go/src/crypto/tls/conn.go:455 +0xcc
crypto/tls.(*Conn).readRecord(0xc820138000, 0x77fa17, 0x0, 0x0)
    /home/sebastian/go/src/crypto/tls/conn.go:540 +0x2d1
crypto/tls.(*Conn).Read(0xc820138000, 0xc8201ac000, 0x1000, 0x1000, 0x0, 0x0, 0x0)
    /home/sebastian/go/src/crypto/tls/conn.go:901 +0x167
net/http.noteEOFReader.Read(0x7f9bb9a2b090, 0xc820138000, 0xc8200de1b8, 0xc8201ac000, 0x1000, 0x1000, 0x0, 0x0, 0x0)
    /home/sebastian/go/src/net/http/transport.go:1370 +0x67
net/http.(*noteEOFReader).Read(0xc8200da580, 0xc8201ac000, 0x1000, 0x1000, 0xc82021fef0, 0x0, 0x0)
    <autogenerated>:126 +0xd0
bufio.(*Reader).fill(0xc8200d3080)
    /home/sebastian/go/src/bufio/bufio.go:97 +0x1e9
bufio.(*Reader).Peek(0xc8200d3080, 0x1, 0x0, 0x0, 0x0, 0x0, 0x0)
    /home/sebastian/go/src/bufio/bufio.go:132 +0xcc
net/http.(*persistConn).readLoop(0xc8200de160)
    /home/sebastian/go/src/net/http/transport.go:876 +0xf7
created by net/http.(*Transport).dialConn
    /home/sebastian/go/src/net/http/transport.go:685 +0xc78

goroutine 23 [select]:
net/http.(*persistConn).readLoop(0xc8200de0b0)
    /home/sebastian/go/src/net/http/transport.go:976 +0xac7
created by net/http.(*Transport).dialConn
    /home/sebastian/go/src/net/http/transport.go:685 +0xc78

goroutine 26 [select]:
net/http.(*persistConn).writeLoop(0xc8200de000)
    /home/sebastian/go/src/net/http/transport.go:1009 +0x40c
created by net/http.(*Transport).dialConn
    /home/sebastian/go/src/net/http/transport.go:686 +0xc9d

goroutine 44 [select]:
net/http.(*persistConn).writeLoop(0xc8200de160)
    /home/sebastian/go/src/net/http/transport.go:1009 +0x40c
created by net/http.(*Transport).dialConn
    /home/sebastian/go/src/net/http/transport.go:686 +0xc9d

goroutine 87 [select]:
net/http.(*persistConn).writeLoop(0xc8200b0fd0)
    /home/sebastian/go/src/net/http/transport.go:1009 +0x40c
created by net/http.(*Transport).dialConn
    /home/sebastian/go/src/net/http/transport.go:686 +0xc9d

goroutine 48 [select]:
net/http.(*persistConn).writeLoop(0xc8200de210)
    /home/sebastian/go/src/net/http/transport.go:1009 +0x40c
created by net/http.(*Transport).dialConn
    /home/sebastian/go/src/net/http/transport.go:686 +0xc9d

goroutine 41 [select]:
net/http.(*persistConn).readLoop(0xc8200dc210)
    /home/sebastian/go/src/net/http/transport.go:976 +0xac7
created by net/http.(*Transport).dialConn
    /home/sebastian/go/src/net/http/transport.go:685 +0xc78

goroutine 70 [IO wait]:
net.runtime_pollWait(0x7f9bb9a6bb40, 0x72, 0xc82000a270)
    /home/sebastian/go/src/runtime/netpoll.go:157 +0x60
net.(*pollDesc).Wait(0xc82011e0d0, 0x72, 0x0, 0x0)
    /home/sebastian/go/src/net/fd_poll_runtime.go:73 +0x3a
net.(*pollDesc).WaitRead(0xc82011e0d0, 0x0, 0x0)
    /home/sebastian/go/src/net/fd_poll_runtime.go:78 +0x36
net.(*netFD).Read(0xc82011e070, 0xc8201e8000, 0x2000, 0x2000, 0x0, 0x7f9bbcb22168, 0xc82000a270)
    /home/sebastian/go/src/net/fd_unix.go:232 +0x23a
net.(*conn).Read(0xc820134000, 0xc8201e8000, 0x2000, 0x2000, 0x0, 0x0, 0x0)
    /home/sebastian/go/src/net/net.go:172 +0xe4
crypto/tls.(*block).readFromUntil(0xc8200c63c0, 0x7f9bb9a6bfc0, 0xc820134000, 0x5, 0x0, 0x0)
    /home/sebastian/go/src/crypto/tls/conn.go:455 +0xcc
crypto/tls.(*Conn).readRecord(0xc820140000, 0x77fa17, 0x0, 0x0)
    /home/sebastian/go/src/crypto/tls/conn.go:540 +0x2d1
crypto/tls.(*Conn).Read(0xc820140000, 0xc8201bb000, 0x1000, 0x1000, 0x0, 0x0, 0x0)
    /home/sebastian/go/src/crypto/tls/conn.go:901 +0x167
net/http.noteEOFReader.Read(0x7f9bb9a2b090, 0xc820140000, 0xc8200b0058, 0xc8201bb000, 0x1000, 0x1000, 0x36300000000, 0x0, 0x0)
    /home/sebastian/go/src/net/http/transport.go:1370 +0x67
net/http.(*noteEOFReader).Read(0xc8201d3a60, 0xc8201bb000, 0x1000, 0x1000, 0x7f9bb9a2b110, 0x0, 0x0)
    <autogenerated>:126 +0xd0
bufio.(*Reader).fill(0xc820112d80)
    /home/sebastian/go/src/bufio/bufio.go:97 +0x1e9
bufio.(*Reader).Peek(0xc820112d80, 0x1, 0x0, 0x0, 0x0, 0x0, 0x0)
    /home/sebastian/go/src/bufio/bufio.go:132 +0xcc
net/http.(*persistConn).readLoop(0xc8200b0000)
    /home/sebastian/go/src/net/http/transport.go:876 +0xf7
created by net/http.(*Transport).dialConn
    /home/sebastian/go/src/net/http/transport.go:685 +0xc78

goroutine 84 [IO wait]:
net.runtime_pollWait(0x7f9bb9a6b900, 0x72, 0xc82000a270)
    /home/sebastian/go/src/runtime/netpoll.go:157 +0x60
net.(*pollDesc).Wait(0xc82011a140, 0x72, 0x0, 0x0)
    /home/sebastian/go/src/net/fd_poll_runtime.go:73 +0x3a
net.(*pollDesc).WaitRead(0xc82011a140, 0x0, 0x0)
    /home/sebastian/go/src/net/fd_poll_runtime.go:78 +0x36
net.(*netFD).Read(0xc82011a0e0, 0xc82026e000, 0x2000, 0x2000, 0x0, 0x7f9bbcb22168, 0xc82000a270)
    /home/sebastian/go/src/net/fd_unix.go:232 +0x23a
net.(*conn).Read(0xc820132008, 0xc82026e000, 0x2000, 0x2000, 0x0, 0x0, 0x0)
    /home/sebastian/go/src/net/net.go:172 +0xe4
crypto/tls.(*block).readFromUntil(0xc82010c330, 0x7f9bb9a6bfc0, 0xc820132008, 0x5, 0x0, 0x0)
    /home/sebastian/go/src/crypto/tls/conn.go:455 +0xcc
crypto/tls.(*Conn).readRecord(0xc8201382c0, 0x77fa17, 0x0, 0x0)
    /home/sebastian/go/src/crypto/tls/conn.go:540 +0x2d1
crypto/tls.(*Conn).Read(0xc8201382c0, 0xc820235000, 0x1000, 0x1000, 0x0, 0x0, 0x0)
    /home/sebastian/go/src/crypto/tls/conn.go:901 +0x167
net/http.noteEOFReader.Read(0x7f9bb9a2b090, 0xc8201382c0, 0xc8200dc108, 0xc820235000, 0x1000, 0x1000, 0xc82028c180, 0x0, 0x0)
    /home/sebastian/go/src/net/http/transport.go:1370 +0x67
net/http.(*noteEOFReader).Read(0xc820294080, 0xc820235000, 0x1000, 0x1000, 0x0, 0x0, 0x0)
    <autogenerated>:126 +0xd0
bufio.(*Reader).fill(0xc820290120)
    /home/sebastian/go/src/bufio/bufio.go:97 +0x1e9
bufio.(*Reader).Peek(0xc820290120, 0x1, 0x0, 0x0, 0x0, 0x0, 0x0)
    /home/sebastian/go/src/bufio/bufio.go:132 +0xcc
net/http.(*persistConn).readLoop(0xc8200dc0b0)
    /home/sebastian/go/src/net/http/transport.go:876 +0xf7
created by net/http.(*Transport).dialConn
    /home/sebastian/go/src/net/http/transport.go:685 +0xc78

goroutine 62 [select]:
net/http.(*persistConn).writeLoop(0xc8200b14a0)
    /home/sebastian/go/src/net/http/transport.go:1009 +0x40c
created by net/http.(*Transport).dialConn
    /home/sebastian/go/src/net/http/transport.go:686 +0xc9d

goroutine 25 [IO wait]:
net.runtime_pollWait(0x7f9bb9a6ba80, 0x72, 0xc82000a270)
    /home/sebastian/go/src/runtime/netpoll.go:157 +0x60
net.(*pollDesc).Wait(0xc82011c0d0, 0x72, 0x0, 0x0)
    /home/sebastian/go/src/net/fd_poll_runtime.go:73 +0x3a
net.(*pollDesc).WaitRead(0xc82011c0d0, 0x0, 0x0)
    /home/sebastian/go/src/net/fd_poll_runtime.go:78 +0x36
net.(*netFD).Read(0xc82011c070, 0xc82022c000, 0x2000, 0x2000, 0x0, 0x7f9bbcb22168, 0xc82000a270)
    /home/sebastian/go/src/net/fd_unix.go:232 +0x23a
net.(*conn).Read(0xc820132010, 0xc82022c000, 0x2000, 0x2000, 0x0, 0x0, 0x0)
    /home/sebastian/go/src/net/net.go:172 +0xe4
crypto/tls.(*block).readFromUntil(0xc82010c3f0, 0x7f9bb9a6bfc0, 0xc820132010, 0x5, 0x0, 0x0)
    /home/sebastian/go/src/crypto/tls/conn.go:455 +0xcc
crypto/tls.(*Conn).readRecord(0xc820138580, 0x77fa17, 0x0, 0x0)
    /home/sebastian/go/src/crypto/tls/conn.go:540 +0x2d1
crypto/tls.(*Conn).Read(0xc820138580, 0xc820255000, 0x1000, 0x1000, 0x0, 0x0, 0x0)
    /home/sebastian/go/src/crypto/tls/conn.go:901 +0x167
net/http.noteEOFReader.Read(0x7f9bb9a2b090, 0xc820138580, 0xc8200de058, 0xc820255000, 0x1000, 0x1000, 0x0, 0x0, 0x0)
    /home/sebastian/go/src/net/http/transport.go:1370 +0x67
net/http.(*noteEOFReader).Read(0xc82025ed40, 0xc820255000, 0x1000, 0x1000, 0xc82021fef0, 0x0, 0x0)
    <autogenerated>:126 +0xd0
bufio.(*Reader).fill(0xc8202604e0)
    /home/sebastian/go/src/bufio/bufio.go:97 +0x1e9
bufio.(*Reader).Peek(0xc8202604e0, 0x1, 0x0, 0x0, 0x0, 0x0, 0x0)
    /home/sebastian/go/src/bufio/bufio.go:132 +0xcc
net/http.(*persistConn).readLoop(0xc8200de000)
    /home/sebastian/go/src/net/http/transport.go:876 +0xf7
created by net/http.(*Transport).dialConn
    /home/sebastian/go/src/net/http/transport.go:685 +0xc78

goroutine 47 [IO wait]:
net.runtime_pollWait(0x7f9bb9a6bc00, 0x72, 0xc82000a270)
    /home/sebastian/go/src/runtime/netpoll.go:157 +0x60
net.(*pollDesc).Wait(0xc82011a0d0, 0x72, 0x0, 0x0)
    /home/sebastian/go/src/net/fd_poll_runtime.go:73 +0x3a
net.(*pollDesc).WaitRead(0xc82011a0d0, 0x0, 0x0)
    /home/sebastian/go/src/net/fd_poll_runtime.go:78 +0x36
net.(*netFD).Read(0xc82011a070, 0xc820210000, 0x2000, 0x2000, 0x0, 0x7f9bbcb22168, 0xc82000a270)
    /home/sebastian/go/src/net/fd_unix.go:232 +0x23a
net.(*conn).Read(0xc820134010, 0xc820210000, 0x2000, 0x2000, 0x0, 0x0, 0x0)
    /home/sebastian/go/src/net/net.go:172 +0xe4
crypto/tls.(*block).readFromUntil(0xc8200c6540, 0x7f9bb9a6bfc0, 0xc820134010, 0x5, 0x0, 0x0)
    /home/sebastian/go/src/crypto/tls/conn.go:455 +0xcc
crypto/tls.(*Conn).readRecord(0xc820140580, 0x77fa17, 0x0, 0x0)
    /home/sebastian/go/src/crypto/tls/conn.go:540 +0x2d1
crypto/tls.(*Conn).Read(0xc820140580, 0xc82022a000, 0x1000, 0x1000, 0x0, 0x0, 0x0)
    /home/sebastian/go/src/crypto/tls/conn.go:901 +0x167
net/http.noteEOFReader.Read(0x7f9bb9a2b090, 0xc820140580, 0xc8200de268, 0xc82022a000, 0x1000, 0x1000, 0xc8200d5bc0, 0x0, 0x0)
    /home/sebastian/go/src/net/http/transport.go:1370 +0x67
net/http.(*noteEOFReader).Read(0xc8200da740, 0xc82022a000, 0x1000, 0x1000, 0x0, 0x0, 0x0)
    <autogenerated>:126 +0xd0
bufio.(*Reader).fill(0xc8200d3560)
    /home/sebastian/go/src/bufio/bufio.go:97 +0x1e9
bufio.(*Reader).Peek(0xc8200d3560, 0x1, 0x0, 0x0, 0x0, 0x0, 0x0)
    /home/sebastian/go/src/bufio/bufio.go:132 +0xcc
net/http.(*persistConn).readLoop(0xc8200de210)
    /home/sebastian/go/src/net/http/transport.go:876 +0xf7
created by net/http.(*Transport).dialConn
    /home/sebastian/go/src/net/http/transport.go:685 +0xc78

goroutine 42 [select]:
net/http.(*persistConn).writeLoop(0xc8200dc210)
    /home/sebastian/go/src/net/http/transport.go:1009 +0x40c
created by net/http.(*Transport).dialConn
    /home/sebastian/go/src/net/http/transport.go:686 +0xc9d

goroutine 24 [select]:
net/http.(*persistConn).writeLoop(0xc8200de0b0)
    /home/sebastian/go/src/net/http/transport.go:1009 +0x40c
created by net/http.(*Transport).dialConn
    /home/sebastian/go/src/net/http/transport.go:686 +0xc9d

goroutine 71 [select]:
net/http.(*persistConn).writeLoop(0xc8200b0000)
    /home/sebastian/go/src/net/http/transport.go:1009 +0x40c
created by net/http.(*Transport).dialConn
    /home/sebastian/go/src/net/http/transport.go:686 +0xc9d

goroutine 58 [IO wait]:
net.runtime_pollWait(0x7f9bb9a6b9c0, 0x72, 0xc82000a270)
    /home/sebastian/go/src/runtime/netpoll.go:157 +0x60
net.(*pollDesc).Wait(0xc82011b640, 0x72, 0x0, 0x0)
    /home/sebastian/go/src/net/fd_poll_runtime.go:73 +0x3a
net.(*pollDesc).WaitRead(0xc82011b640, 0x0, 0x0)
    /home/sebastian/go/src/net/fd_poll_runtime.go:78 +0x36
net.(*netFD).Read(0xc82011b5e0, 0xc8203c8000, 0x1000, 0x1000, 0x0, 0x7f9bbcb22168, 0xc82000a270)
    /home/sebastian/go/src/net/fd_unix.go:232 +0x23a
net.(*conn).Read(0xc820120008, 0xc8203c8000, 0x1000, 0x1000, 0x0, 0x0, 0x0)
    /home/sebastian/go/src/net/net.go:172 +0xe4
net/http.noteEOFReader.Read(0x7f9bb9a6bfc0, 0xc820120008, 0xc820118898, 0xc8203c8000, 0x1000, 0x1000, 0xc820113d40, 0x0, 0x0)
    /home/sebastian/go/src/net/http/transport.go:1370 +0x67
net/http.(*noteEOFReader).Read(0xc820221320, 0xc8203c8000, 0x1000, 0x1000, 0x0, 0x0, 0x0)
    <autogenerated>:126 +0xd0
bufio.(*Reader).fill(0xc82028c300)
    /home/sebastian/go/src/bufio/bufio.go:97 +0x1e9
bufio.(*Reader).Peek(0xc82028c300, 0x1, 0x0, 0x0, 0x0, 0x0, 0x0)
    /home/sebastian/go/src/bufio/bufio.go:132 +0xcc
net/http.(*persistConn).readLoop(0xc820118840)
    /home/sebastian/go/src/net/http/transport.go:876 +0xf7
created by net/http.(*Transport).dialConn
    /home/sebastian/go/src/net/http/transport.go:685 +0xc78

goroutine 91 [select]:
net/http.(*persistConn).writeLoop(0xc8200b13f0)
    /home/sebastian/go/src/net/http/transport.go:1009 +0x40c
created by net/http.(*Transport).dialConn
    /home/sebastian/go/src/net/http/transport.go:686 +0xc9d

goroutine 86 [IO wait]:
net.runtime_pollWait(0x7f9bb9a6b6c0, 0x72, 0xc82000a270)
    /home/sebastian/go/src/runtime/netpoll.go:157 +0x60
net.(*pollDesc).Wait(0xc8202700d0, 0x72, 0x0, 0x0)
    /home/sebastian/go/src/net/fd_poll_runtime.go:73 +0x3a
net.(*pollDesc).WaitRead(0xc8202700d0, 0x0, 0x0)
    /home/sebastian/go/src/net/fd_poll_runtime.go:78 +0x36
net.(*netFD).Read(0xc820270070, 0xc8202f6000, 0x2000, 0x2000, 0x0, 0x7f9bbcb22168, 0xc82000a270)
    /home/sebastian/go/src/net/fd_unix.go:232 +0x23a
net.(*conn).Read(0xc820032080, 0xc8202f6000, 0x2000, 0x2000, 0x0, 0x0, 0x0)
    /home/sebastian/go/src/net/net.go:172 +0xe4
crypto/tls.(*block).readFromUntil(0xc8201a7650, 0x7f9bb9a6bfc0, 0xc820032080, 0x5, 0x0, 0x0)
    /home/sebastian/go/src/crypto/tls/conn.go:455 +0xcc
crypto/tls.(*Conn).readRecord(0xc8200b2dc0, 0x77fa17, 0x0, 0x0)
    /home/sebastian/go/src/crypto/tls/conn.go:540 +0x2d1
crypto/tls.(*Conn).Read(0xc8200b2dc0, 0xc82031b000, 0x1000, 0x1000, 0x0, 0x0, 0x0)
    /home/sebastian/go/src/crypto/tls/conn.go:901 +0x167
net/http.noteEOFReader.Read(0x7f9bb9a2b090, 0xc8200b2dc0, 0xc8200b1028, 0xc82031b000, 0x1000, 0x1000, 0xc820260b40, 0x0, 0x0)
    /home/sebastian/go/src/net/http/transport.go:1370 +0x67
net/http.(*noteEOFReader).Read(0xc8202fd8e0, 0xc82031b000, 0x1000, 0x1000, 0x0, 0x0, 0x0)
    <autogenerated>:126 +0xd0
bufio.(*Reader).fill(0xc820290900)
    /home/sebastian/go/src/bufio/bufio.go:97 +0x1e9
bufio.(*Reader).Peek(0xc820290900, 0x1, 0x0, 0x0, 0x0, 0x0, 0x0)
    /home/sebastian/go/src/bufio/bufio.go:132 +0xcc
net/http.(*persistConn).readLoop(0xc8200b0fd0)
    /home/sebastian/go/src/net/http/transport.go:876 +0xf7
created by net/http.(*Transport).dialConn
    /home/sebastian/go/src/net/http/transport.go:685 +0xc78

goroutine 90 [IO wait]:
net.runtime_pollWait(0x7f9bb9a6b780, 0x72, 0xc82000a270)
    /home/sebastian/go/src/runtime/netpoll.go:157 +0x60
net.(*pollDesc).Wait(0xc820270990, 0x72, 0x0, 0x0)
    /home/sebastian/go/src/net/fd_poll_runtime.go:73 +0x3a
net.(*pollDesc).WaitRead(0xc820270990, 0x0, 0x0)
    /home/sebastian/go/src/net/fd_poll_runtime.go:78 +0x36
net.(*netFD).Read(0xc820270930, 0xc820361000, 0x1000, 0x1000, 0x0, 0x7f9bbcb22168, 0xc82000a270)
    /home/sebastian/go/src/net/fd_unix.go:232 +0x23a
net.(*conn).Read(0xc820134028, 0xc820361000, 0x1000, 0x1000, 0x0, 0x0, 0x0)
    /home/sebastian/go/src/net/net.go:172 +0xe4
net/http.noteEOFReader.Read(0x7f9bb9a6bfc0, 0xc820134028, 0xc8200b1448, 0xc820361000, 0x1000, 0x1000, 0xc820261560, 0x0, 0x0)
    /home/sebastian/go/src/net/http/transport.go:1370 +0x67
net/http.(*noteEOFReader).Read(0xc8202fd9e0, 0xc820361000, 0x1000, 0x1000, 0xc82002ccf0, 0x0, 0x0)
    <autogenerated>:126 +0xd0
bufio.(*Reader).fill(0xc820290a80)
    /home/sebastian/go/src/bufio/bufio.go:97 +0x1e9
bufio.(*Reader).Peek(0xc820290a80, 0x1, 0x0, 0x0, 0x0, 0x0, 0x0)
    /home/sebastian/go/src/bufio/bufio.go:132 +0xcc
net/http.(*persistConn).readLoop(0xc8200b13f0)
    /home/sebastian/go/src/net/http/transport.go:876 +0xf7
created by net/http.(*Transport).dialConn
    /home/sebastian/go/src/net/http/transport.go:685 +0xc78

goroutine 85 [select]:
net/http.(*persistConn).writeLoop(0xc8200dc0b0)
    /home/sebastian/go/src/net/http/transport.go:1009 +0x40c
created by net/http.(*Transport).dialConn
    /home/sebastian/go/src/net/http/transport.go:686 +0xc9d

goroutine 61 [IO wait]:
net.runtime_pollWait(0x7f9bb9a6bd80, 0x72, 0xc82000a270)
    /home/sebastian/go/src/runtime/netpoll.go:157 +0x60
net.(*pollDesc).Wait(0xc82011d410, 0x72, 0x0, 0x0)
    /home/sebastian/go/src/net/fd_poll_runtime.go:73 +0x3a
net.(*pollDesc).WaitRead(0xc82011d410, 0x0, 0x0)
    /home/sebastian/go/src/net/fd_poll_runtime.go:78 +0x36
net.(*netFD).Read(0xc82011d3b0, 0xc8203cc000, 0x1000, 0x1000, 0x0, 0x7f9bbcb22168, 0xc82000a270)
    /home/sebastian/go/src/net/fd_unix.go:232 +0x23a
net.(*conn).Read(0xc820120010, 0xc8203cc000, 0x1000, 0x1000, 0x0, 0x0, 0x0)
    /home/sebastian/go/src/net/net.go:172 +0xe4
net/http.noteEOFReader.Read(0x7f9bb9a6bfc0, 0xc820120010, 0xc8200b14f8, 0xc8203cc000, 0x1000, 0x1000, 0xc820113da0, 0x0, 0x0)
    /home/sebastian/go/src/net/http/transport.go:1370 +0x67
net/http.(*noteEOFReader).Read(0xc820221400, 0xc8203cc000, 0x1000, 0x1000, 0x1, 0x0, 0x0)
    <autogenerated>:126 +0xd0
bufio.(*Reader).fill(0xc82028c480)
    /home/sebastian/go/src/bufio/bufio.go:97 +0x1e9
bufio.(*Reader).Peek(0xc82028c480, 0x1, 0x0, 0x0, 0x0, 0x0, 0x0)
    /home/sebastian/go/src/bufio/bufio.go:132 +0xcc
net/http.(*persistConn).readLoop(0xc8200b14a0)
    /home/sebastian/go/src/net/http/transport.go:876 +0xf7
created by net/http.(*Transport).dialConn
    /home/sebastian/go/src/net/http/transport.go:685 +0xc78

goroutine 59 [select]:
net/http.(*persistConn).writeLoop(0xc820118840)
    /home/sebastian/go/src/net/http/transport.go:1009 +0x40c
created by net/http.(*Transport).dialConn
    /home/sebastian/go/src/net/http/transport.go:686 +0xc9d
exit status 2

[davecheney]

Thank you for this bug report.

Have you confirmed your code is free of data races ? If so, can you please include some sample code that demonstrates the issue so that others can try to confirm the issue you are seeing.

[sebcat]

Code used to replicate issue seen in another application (with URLs redacted):

package main

import (
    "crypto/tls"
    "io"
    "io/ioutil"
    "log"
    "net"
    "net/http"
    "sync"
    "time"
)

var urllist = []string{
// redacted
}

const nconcurrent = 10

func main() {
    t := http.Transport{
        TLSHandshakeTimeout:   20 * time.Second,
        ResponseHeaderTimeout: 1 * time.Minute,
        Proxy: http.ProxyFromEnvironment,
        Dial: (&net.Dialer{
            Timeout:   20 * time.Second,
            KeepAlive: 30 * time.Second,
            DualStack: true,
        }).Dial,
        TLSClientConfig: &tls.Config{
            InsecureSkipVerify: true,
        },
    }

    ch := make(chan string)
    var wg sync.WaitGroup
    wg.Add(nconcurrent)
    for i := 0; i < nconcurrent; i++ {
        go func() {
            for urlstr := range ch {
                req, err := http.NewRequest("GET", urlstr, nil)
                if err != nil {
                    log.Fatal(err)
                }

                resp, err := t.RoundTrip(req)
                if err != nil {
                    log.Println("RoundTrip", req.URL, err)
                } else {
                    log.Println("RoundTrip", req.URL, resp.Status, resp.Proto)
                    if resp.Body != nil {
                        b := io.LimitReader(resp.Body, 10000000)
                        _, err = ioutil.ReadAll(b)
                        if err != nil {
                            log.Println("ReadAll", req.URL, err)
                        }
                    }
                }
            }

            wg.Done()
        }()
    }

    for _, urlstr := range urllist {
        ch <- urlstr
    }

    log.Println("Feed completed")
    close(ch)
    wg.Wait()
}

-race yields:

==================
WARNING: DATA RACE
Read by goroutine 9:
  bufio.(*Reader).ReadSlice()
      /home/sebastian/go/src/bufio/bufio.go:306 +0x75
  net/http/internal.readLine()
      /home/sebastian/go/src/net/http/internal/chunked.go:110 +0x61
  net/http/internal.(*chunkedReader).beginChunk()
      /home/sebastian/go/src/net/http/internal/chunked.go:47 +0x5a
  net/http/internal.(*chunkedReader).Read()
      /home/sebastian/go/src/net/http/internal/chunked.go:77 +0x11a
  net/http.(*body).readLocked()
      /home/sebastian/go/src/net/http/transfer.go:632 +0x113
  net/http.(*body).Read()
      /home/sebastian/go/src/net/http/transfer.go:624 +0x157
  net/http.(*bodyEOFSignal).Read()
      /home/sebastian/go/src/net/http/transport.go:1296 +0x2df
  io.(*LimitedReader).Read()
      /home/sebastian/go/src/io/io.go:427 +0x15d
  bytes.(*Buffer).ReadFrom()
      /home/sebastian/go/src/bytes/buffer.go:173 +0x414
  io/ioutil.readAll()
      /home/sebastian/go/src/io/ioutil/ioutil.go:33 +0x1a0
  io/ioutil.ReadAll()
      /home/sebastian/go/src/io/ioutil/ioutil.go:42 +0x71
  main.main.func1()
      /home/sebastian/urls.go:75 +0x5b7

Previous write by goroutine 45:
  bufio.(*Reader).fill()
      /home/sebastian/go/src/bufio/bufio.go:88 +0x1cf
  bufio.(*Reader).Peek()
      /home/sebastian/go/src/bufio/bufio.go:132 +0x186
  net/http.(*persistConn).readLoop()
      /home/sebastian/go/src/net/http/transport.go:876 +0x14d

Goroutine 9 (running) created at:
  main.main()
      /home/sebastian/urls.go:83 +0x2e5

Goroutine 45 (running) created at:
  net/http.(*Transport).dialConn()
      /home/sebastian/go/src/net/http/transport.go:685 +0x11bf
  net/http.(*Transport).getConn.func4()
      /home/sebastian/go/src/net/http/transport.go:549 +0x73
==================
==================
WARNING: DATA RACE
Read by goroutine 9:
  bufio.(*Reader).ReadSlice()
      /home/sebastian/go/src/bufio/bufio.go:306 +0x94
  net/http/internal.readLine()
      /home/sebastian/go/src/net/http/internal/chunked.go:110 +0x61
  net/http/internal.(*chunkedReader).beginChunk()
      /home/sebastian/go/src/net/http/internal/chunked.go:47 +0x5a
  net/http/internal.(*chunkedReader).Read()
      /home/sebastian/go/src/net/http/internal/chunked.go:77 +0x11a
  net/http.(*body).readLocked()
      /home/sebastian/go/src/net/http/transfer.go:632 +0x113
  net/http.(*body).Read()
      /home/sebastian/go/src/net/http/transfer.go:624 +0x157
  net/http.(*bodyEOFSignal).Read()
      /home/sebastian/go/src/net/http/transport.go:1296 +0x2df
  io.(*LimitedReader).Read()
      /home/sebastian/go/src/io/io.go:427 +0x15d
  bytes.(*Buffer).ReadFrom()
      /home/sebastian/go/src/bytes/buffer.go:173 +0x414
  io/ioutil.readAll()
      /home/sebastian/go/src/io/ioutil/ioutil.go:33 +0x1a0
  io/ioutil.ReadAll()
      /home/sebastian/go/src/io/ioutil/ioutil.go:42 +0x71
  main.main.func1()
      /home/sebastian/urls.go:75 +0x5b7

Previous write by goroutine 45:
  bufio.(*Reader).fill()
      /home/sebastian/go/src/bufio/bufio.go:87 +0x189
  bufio.(*Reader).Peek()
      /home/sebastian/go/src/bufio/bufio.go:132 +0x186
  net/http.(*persistConn).readLoop()
      /home/sebastian/go/src/net/http/transport.go:876 +0x14d

Goroutine 9 (running) created at:
  main.main()
      /home/sebastian/urls.go:83 +0x2e5

Goroutine 45 (running) created at:
  net/http.(*Transport).dialConn()
      /home/sebastian/go/src/net/http/transport.go:685 +0x11bf
  net/http.(*Transport).getConn.func4()
      /home/sebastian/go/src/net/http/transport.go:549 +0x73

EDIT: changed the code above to only access resp if RoundTrip was successful. Reran test to confirm that the issue persists (it does).
EDIT2: Also reproducible with http.DefaultTransport

[davecheney]

Thank you for providing your sample code. Although it should not matter for this issue, I cannot see where you are closing the response body.

/cc @bradfitz

[sebcat]

I wanted a small piece of example code exhibiting the problem I saw in another application. I should have taken more care in writing it. I've now tested the example above with resp.Body.Close(). The problem persists.

[ianlancetaylor]

I'm not clear on your initial report: does this failure happen with 1.4.2, or only with 1.5?

[sebcat]

It happens on both 1.4.2 and 1.5.

EDIT: paths above relating to /home/sebastian/go is go 1.5

[bradfitz]

Can you email me privately the URL(s) I can hit to reproduce this?

I am <my github username>@golang.org.

[sebcat]

Email sent

[bradfitz]

I can't reproduce. Can you reproduce with Go tip? (what is to become Go 1.6 soon-ish)

[sebcat]

With same code/line-numbers as in email, using master (assuming master == tip):

$ go version
go version devel +bb6fb92 Thu Dec 3 03:53:35 2015 +0000 linux/amd64
$ go build -race golang_crash.go 
$ ./golang_crash 
2015/12/03 14:03:06 RoundTrip [url] 200 OK HTTP/1.1
2015/12/03 14:03:06 RoundTrip [url] 204 Request format is unrecognized for URL unexpectedly ending in '/'. HTTP/1.1
==================
WARNING: DATA RACE
Read by goroutine 9:
  bufio.(*Reader).ReadSlice()
      /home/sebastian/go-tip/src/bufio/bufio.go:306 +0x75
  net/http/internal.readChunkLine()
      /home/sebastian/go-tip/src/net/http/internal/chunked.go:110 +0x60
  net/http/internal.(*chunkedReader).beginChunk()
      /home/sebastian/go-tip/src/net/http/internal/chunked.go:47 +0x5a
  net/http/internal.(*chunkedReader).Read()
      /home/sebastian/go-tip/src/net/http/internal/chunked.go:77 +0x11a
  net/http.(*body).readLocked()
      /home/sebastian/go-tip/src/net/http/transfer.go:642 +0x113
  net/http.(*body).Read()
      /home/sebastian/go-tip/src/net/http/transfer.go:634 +0x157
  net/http.(*bodyEOFSignal).Read()
      /home/sebastian/go-tip/src/net/http/transport.go:1480 +0x2df
  io.(*LimitedReader).Read()
      /home/sebastian/go-tip/src/io/io.go:426 +0x15d
  bytes.(*Buffer).ReadFrom()
      /home/sebastian/go-tip/src/bytes/buffer.go:173 +0x414
  io/ioutil.readAll()
      /home/sebastian/go-tip/src/io/ioutil/ioutil.go:33 +0x1a2
  io/ioutil.ReadAll()
      /home/sebastian/go-tip/src/io/ioutil/ioutil.go:42 +0x71
  main.main.func1()
      /home/sebastian/src/golang_crash.go:75 +0x8bb

Previous write by goroutine 51:
  bufio.(*Reader).fill()
      /home/sebastian/go-tip/src/bufio/bufio.go:88 +0x1cf
  bufio.(*Reader).Peek()
      /home/sebastian/go-tip/src/bufio/bufio.go:132 +0x186
  net/http.(*persistConn).readLoop()
      /home/sebastian/go-tip/src/net/http/transport.go:995 +0x13e

Goroutine 9 (running) created at:
  main.main()
      /home/sebastian/src/golang_crash.go:84 +0x2eb

Goroutine 51 (running) created at:
  net/http.(*Transport).dialConn()
      /home/sebastian/go-tip/src/net/http/transport.go:790 +0x14c0
  net/http.(*Transport).getConn.func4()
      /home/sebastian/go-tip/src/net/http/transport.go:648 +0x73
==================
==================
WARNING: DATA RACE
Read by goroutine 9:
  bufio.(*Reader).ReadSlice()
      /home/sebastian/go-tip/src/bufio/bufio.go:306 +0x94
  net/http/internal.readChunkLine()
      /home/sebastian/go-tip/src/net/http/internal/chunked.go:110 +0x60
  net/http/internal.(*chunkedReader).beginChunk()
      /home/sebastian/go-tip/src/net/http/internal/chunked.go:47 +0x5a
  net/http/internal.(*chunkedReader).Read()
      /home/sebastian/go-tip/src/net/http/internal/chunked.go:77 +0x11a
  net/http.(*body).readLocked()
      /home/sebastian/go-tip/src/net/http/transfer.go:642 +0x113
  net/http.(*body).Read()
      /home/sebastian/go-tip/src/net/http/transfer.go:634 +0x157
2015/12/03 14:03:06 RoundTrip [url] 403 Forbidden HTTP/1.1
  net/http.(*bodyEOFSignal).Read()
      /home/sebastian/go-tip/src/net/http/transport.go:1480 +0x2df
  io.(*LimitedReader).Read()
      /home/sebastian/go-tip/src/io/io.go:426 +0x15d
  bytes.(*Buffer).ReadFrom()
      /home/sebastian/go-tip/src/bytes/buffer.go:173 +0x414
  io/ioutil.readAll()
      /home/sebastian/go-tip/src/io/ioutil/ioutil.go:33 +0x1a2
  io/ioutil.ReadAll()
      /home/sebastian/go-tip/src/io/ioutil/ioutil.go:42 +0x71
  main.main.func1()
      /home/sebastian/src/golang_crash.go:75 +0x8bb

Previous write by goroutine 51:
  bufio.(*Reader).fill()
      /home/sebastian/go-tip/src/bufio/bufio.go:87 +0x189
  bufio.(*Reader).Peek()
      /home/sebastian/go-tip/src/bufio/bufio.go:132 +0x186
  net/http.(*persistConn).readLoop()
      /home/sebastian/go-tip/src/net/http/transport.go:995 +0x13e

Goroutine 9 (running) created at:
  main.main()
      /home/sebastian/src/golang_crash.go:84 +0x2eb

Goroutine 51 (running) created at:
  net/http.(*Transport).dialConn()
      /home/sebastian/go-tip/src/net/http/transport.go:790 +0x14c0
  net/http.(*Transport).getConn.func4()
      /home/sebastian/go-tip/src/net/http/transport.go:648 +0x73
==================
2015/12/03 14:03:06 RoundTrip [url] 403 Forbidden HTTP/1.1
2015/12/03 14:03:06 RoundTrip [url] 200 OK HTTP/1.1
2015/12/03 14:03:06 RoundTrip [url] 403 Forbidden HTTP/1.1
2015/12/03 14:03:06 RoundTrip [url] 403 Forbidden HTTP/1.1
2015/12/03 14:03:06 RoundTrip [url] 404 Not Found HTTP/1.1
2015/12/03 14:03:06 RoundTrip [url] 403 Forbidden HTTP/1.1
==================
WARNING: DATA RACE
Read by goroutine 51:
  bufio.(*Reader).ReadSlice()
      /home/sebastian/go-tip/src/bufio/bufio.go:333 +0x281
  bufio.(*Reader).ReadLine()
      /home/sebastian/go-tip/src/bufio/bufio.go:357 +0x6c
  net/textproto.(*Reader).readLineSlice()
      /home/sebastian/go-tip/src/net/textproto/reader.go:55 +0xa2
  net/textproto.(*Reader).ReadLine()
      /home/sebastian/go-tip/src/net/textproto/reader.go:36 +0x4d
  net/http.ReadResponse()
      /home/sebastian/go-tip/src/net/http/response.go:128 +0x182
  net/http.(*persistConn).readLoop()
      /home/sebastian/go-tip/src/net/http/transport.go:1018 +0x675

Previous write by goroutine 9:
  runtime.slicecopy()
      /home/sebastian/go-tip/src/runtime/slice.go:113 +0x0
  crypto/tls.(*Conn).Read()
      /home/sebastian/go-tip/src/crypto/tls/conn.go:928 +0x39f
  net/http.noteEOFReader.Read()
      /home/sebastian/go-tip/src/net/http/transport.go:1554 +0x74
  net/http.(*noteEOFReader).Read()
      <autogenerated>:260 +0xf7
  bufio.(*Reader).fill()
      /home/sebastian/go-tip/src/bufio/bufio.go:97 +0x364
  bufio.(*Reader).ReadSlice()
      /home/sebastian/go-tip/src/bufio/bufio.go:328 +0x5a8
  net/http/internal.readChunkLine()
      /home/sebastian/go-tip/src/net/http/internal/chunked.go:110 +0x60
  net/http/internal.(*chunkedReader).beginChunk()
      /home/sebastian/go-tip/src/net/http/internal/chunked.go:47 +0x5a
  net/http/internal.(*chunkedReader).Read()
      /home/sebastian/go-tip/src/net/http/internal/chunked.go:77 +0x11a
  net/http.(*body).readLocked()
      /home/sebastian/go-tip/src/net/http/transfer.go:642 +0x113
  net/http.(*body).Read()
      /home/sebastian/go-tip/src/net/http/transfer.go:634 +0x157
  net/http.(*bodyEOFSignal).Read()
      /home/sebastian/go-tip/src/net/http/transport.go:1480 +0x2df
  io.(*LimitedReader).Read()
      /home/sebastian/go-tip/src/io/io.go:426 +0x15d
  bytes.(*Buffer).ReadFrom()
      /home/sebastian/go-tip/src/bytes/buffer.go:173 +0x414
  io/ioutil.readAll()
      /home/sebastian/go-tip/src/io/ioutil/ioutil.go:33 +0x1a2
  io/ioutil.ReadAll()
      /home/sebastian/go-tip/src/io/ioutil/ioutil.go:42 +0x71
  main.main.func1()
      /home/sebastian/src/golang_crash.go:75 +0x8bb

Goroutine 51 (running) created at:
  net/http.(*Transport).dialConn()
      /home/sebastian/go-tip/src/net/http/transport.go:790 +0x14c0
  net/http.(*Transport).getConn.func4()
      /home/sebastian/go-tip/src/net/http/transport.go:648 +0x73

Goroutine 9 (running) created at:
  main.main()
      /home/sebastian/src/golang_crash.go:84 +0x2eb
==================
panic: runtime error: slice bounds out of range [recovered]
    panic: runtime error: slice bounds out of range

goroutine 22 [running]:
io/ioutil.readAll.func1(0xc82004bd78)
    /home/sebastian/go-tip/src/io/ioutil/ioutil.go:30 +0x17d
bufio.(*Reader).ReadSlice(0xc8202d6060, 0xc82010f40a, 0x0, 0x0, 0x0, 0x0, 0x0)
    /home/sebastian/go-tip/src/bufio/bufio.go:306 +0x5b3
net/http/internal.readChunkLine(0xc8202d6060, 0x0, 0x0, 0x0, 0x0, 0x0)
    /home/sebastian/go-tip/src/net/http/internal/chunked.go:110 +0x61
net/http/internal.(*chunkedReader).beginChunk(0xc8202fafc0)
    /home/sebastian/go-tip/src/net/http/internal/chunked.go:47 +0x5b
net/http/internal.(*chunkedReader).Read(0xc8202fafc0, 0xc8202a8600, 0x200, 0x200, 0x0, 0x0, 0x0)
    /home/sebastian/go-tip/src/net/http/internal/chunked.go:77 +0x11b
net/http.(*body).readLocked(0xc820075f80, 0xc8202a8600, 0x200, 0x200, 0xc820075fd0, 0x0, 0x0)
    /home/sebastian/go-tip/src/net/http/transfer.go:642 +0x114
net/http.(*body).Read(0xc820075f80, 0xc8202a8600, 0x200, 0x200, 0x0, 0x0, 0x0)
    /home/sebastian/go-tip/src/net/http/transfer.go:634 +0x158
net/http.(*bodyEOFSignal).Read(0xc820075fc0, 0xc8202a8600, 0x200, 0x200, 0x0, 0x0, 0x0)
    /home/sebastian/go-tip/src/net/http/transport.go:1480 +0x2e0
io.(*LimitedReader).Read(0xc82032ad80, 0xc8202a8600, 0x200, 0x200, 0x774360, 0x0, 0x0)
    /home/sebastian/go-tip/src/io/io.go:426 +0x15e
bytes.(*Buffer).ReadFrom(0xc82004bcd0, 0x7f4eaf2538c0, 0xc82032ad80, 0x0, 0x0, 0x0)
    /home/sebastian/go-tip/src/bytes/buffer.go:173 +0x415
io/ioutil.readAll(0x7f4eaf2538c0, 0xc82032ad80, 0x200, 0x0, 0x0, 0x0, 0x0, 0x0)
    /home/sebastian/go-tip/src/io/ioutil/ioutil.go:33 +0x1a3
io/ioutil.ReadAll(0x7f4eaf2538c0, 0xc82032ad80, 0x0, 0x0, 0x0, 0x0, 0x0)
    /home/sebastian/go-tip/src/io/ioutil/ioutil.go:42 +0x72
main.main.func1(0xc820072180, 0xc8200ec210, 0xc820076c70)
    /home/sebastian/src/golang_crash.go:75 +0x8bc
created by main.main
    /home/sebastian/src/golang_crash.go:84 +0x2ec

[bradfitz]

@sebcat, can you try again with the latest code from master? I was never able to reproduce this myself but I wonder if one my recent commits might have fixed this.

The same output as before would be great.

Thanks!

[bradfitz]

(In particular, I think https://golang.org/cl/17890 could've fixed this)