graph 崩溃（concurrent map read and map write）

[freedomkk-qfeng]

用的是最新版本的代码（gitversion 2d27dc2）
长期运行一直很稳定，今天凌晨意外崩溃了。。
可能和当时磁盘IO偏高有关
日志显示这样：

fatal error: concurrent map read and map write

goroutine 61213088 [running]:
runtime.throw(0x86725a, 0x21)
/usr/local/go/src/runtime/panic.go:566 +0x95 fp=0xc438085250 sp=0xc438085230
runtime.mapaccess2(0x7e6e60, 0xc42000d650, 0xc4399b9ac0, 0xc4380852e0, 0xc4380852e0)
/usr/local/go/src/runtime/hashmap.go:340 +0x249 fp=0xc438085298 sp=0xc438085250
reflect.mapaccess(0x7e6e60, 0xc42000d650, 0xc4399b9ac0, 0xc42000d650)
/usr/local/go/src/runtime/hashmap.go:1008 +0x3f fp=0xc4380852d0 sp=0xc438085298
reflect.Value.MapIndex(0x7e6e60, 0xc420088220, 0x195, 0x7c6f20, 0xc4399b9ac0, 0x98, 0x7dcc40, 0xc4399b9af0, 0x94)
/usr/local/go/src/reflect/value.go:1040 +0x128 fp=0xc438085358 sp=0xc4380852d0
encoding/json.(*mapEncoder).encode(0xc42012c208, 0xc42032e0b0, 0x7e6e60, 0xc420088220, 0x195, 0x100)
/usr/local/go/src/encoding/json/encode.go:646 +0x4f0 fp=0xc4380854b0 sp=0xc438085358
encoding/json.(*mapEncoder).(encoding/json.encode)-fm(0xc42032e0b0, 0x7e6e60, 0xc420088220, 0x195, 0x100)
/usr/local/go/src/encoding/json/encode.go:662 +0x64 fp=0xc4380854f0 sp=0xc4380854b0
encoding/json.(*structEncoder).encode(0xc420418ba0, 0xc42032e0b0, 0x83a420, 0xc4200881c0, 0x199, 0x100)
/usr/local/go/src/encoding/json/encode.go:601 +0x253 fp=0xc438085650 sp=0xc4380854f0
encoding/json.(*structEncoder).(encoding/json.encode)-fm(0xc42032e0b0, 0x83a420, 0xc4200881c0, 0x199, 0xc420080100)
/usr/local/go/src/encoding/json/encode.go:615 +0x64 fp=0xc438085690 sp=0xc438085650
encoding/json.(*ptrEncoder).encode(0xc42012c210, 0xc42032e0b0, 0x827500, 0xc4200881c0, 0x16, 0x820100)
/usr/local/go/src/encoding/json/encode.go:742 +0xe3 fp=0xc4380856d0 sp=0xc438085690
encoding/json.(*ptrEncoder).(encoding/json.encode)-fm(0xc42032e0b0, 0x827500, 0xc4200881c0, 0x16, 0xc420080100)
/usr/local/go/src/encoding/json/encode.go:747 +0x64 fp=0xc438085710 sp=0xc4380856d0
encoding/json.(*encodeState).reflectValue(0xc42032e0b0, 0x827500, 0xc4200881c0, 0x16, 0xc420080100)
/usr/local/go/src/encoding/json/encode.go:307 +0x82 fp=0xc438085748 sp=0xc438085710
encoding/json.interfaceEncoder(0xc42032e0b0, 0x7dcc40, 0xc42e1b02a0, 0x194, 0x7d0100)
/usr/local/go/src/encoding/json/encode.go:573 +0xdb fp=0xc438085788 sp=0xc438085748
encoding/json.(*arrayEncoder).encode(0xc42012c1a8, 0xc42032e0b0, 0x7bfa40, 0xc4416efaa0, 0x97, 0x100)
/usr/local/go/src/encoding/json/encode.go:723 +0xee fp=0xc4380857e0 sp=0xc438085788
encoding/json.(*arrayEncoder).(encoding/json.encode)-fm(0xc42032e0b0, 0x7bfa40, 0xc4416efaa0, 0x97, 0x100)
/usr/local/go/src/encoding/json/encode.go:730 +0x64 fp=0xc438085820 sp=0xc4380857e0
encoding/json.(*sliceEncoder).encode(0xc42012c1b0, 0xc42032e0b0, 0x7bfa40, 0xc4416efaa0, 0x97, 0x7b0100)
/usr/local/go/src/encoding/json/encode.go:697 +0xc1 fp=0xc438085860 sp=0xc438085820
encoding/json.(*sliceEncoder).(encoding/json.encode)-fm(0xc42032e0b0, 0x7bfa40, 0xc4416efaa0, 0x97, 0xc4416e0100)
/usr/local/go/src/encoding/json/encode.go:709 +0x64 fp=0xc4380858a0 sp=0xc438085860
encoding/json.(*encodeState).reflectValue(0xc42032e0b0, 0x7bfa40, 0xc4416efaa0, 0x97, 0xc4416e0100)
/usr/local/go/src/encoding/json/encode.go:307 +0x82 fp=0xc4380858d8 sp=0xc4380858a0
encoding/json.interfaceEncoder(0xc42032e0b0, 0x7dcc40, 0xc4416efcb0, 0x94, 0x100)
/usr/local/go/src/encoding/json/encode.go:573 +0xdb fp=0xc438085918 sp=0xc4380858d8
encoding/json.(*structEncoder).encode(0xc420418a20, 0xc42032e0b0, 0x802880, 0xc4416efca0, 0x99, 0x800100)
/usr/local/go/src/encoding/json/encode.go:601 +0x253 fp=0xc438085a78 sp=0xc438085918
encoding/json.(*structEncoder).(encoding/json.encode)-fm(0xc42032e0b0, 0x802880, 0xc4416efca0, 0x99, 0xc4416e0100)
/usr/local/go/src/encoding/json/encode.go:615 +0x64 fp=0xc438085ab8 sp=0xc438085a78
encoding/json.(*encodeState).reflectValue(0xc42032e0b0, 0x802880, 0xc4416efca0, 0x99, 0x100)
/usr/local/go/src/encoding/json/encode.go:307 +0x82 fp=0xc438085af0 sp=0xc438085ab8
encoding/json.(*encodeState).marshal(0xc42032e0b0, 0x802880, 0xc4416efca0, 0x100, 0x0, 0x0)
/usr/local/go/src/encoding/json/encode.go:280 +0xb8 fp=0xc438085b28 sp=0xc438085af0
encoding/json.Marshal(0x802880, 0xc4416efca0, 0x20, 0xc4204d2401, 0xc4416efca0, 0xc42bde3bd0, 0x41131b)
/usr/local/go/src/encoding/json/encode.go:145 +0x8f fp=0xc438085b70 sp=0xc438085b28
github.com/open-falcon/graph/http.RenderJson(0xc3d3e0, 0xc4287aa410, 0x802880, 0xc4416efca0)
/usr/local/gopath/src/github.com/open-falcon/graph/http/http.go:32 +0x39 fp=0xc438085bd0 sp=0xc438085b70
github.com/open-falcon/graph/http.RenderDataJson(0xc3d3e0, 0xc4287aa410, 0x7bfa40, 0xc4416efaa0)
/usr/local/gopath/src/github.com/open-falcon/graph/http/http.go:42 +0xb4 fp=0xc438085c28 sp=0xc438085bd0
github.com/open-falcon/graph/http.configProcRoutes.func2(0xc3d3e0, 0xc4287aa410, 0xc4336d50e0)
/usr/local/gopath/src/github.com/open-falcon/graph/http/proc_http.go:20 +0x92 fp=0xc438085c78 sp=0xc438085c28
net/http.HandlerFunc.ServeHTTP(0x893c08, 0xc3d3e0, 0xc4287aa410, 0xc4336d50e0)
/usr/local/go/src/net/http/server.go:1726 +0x44 fp=0xc438085ca0 sp=0xc438085c78
net/http.(*ServeMux).ServeHTTP(0xc53c40, 0xc3d3e0, 0xc4287aa410, 0xc4336d50e0)
/usr/local/go/src/net/http/server.go:2022 +0x7f fp=0xc438085ce0 sp=0xc438085ca0
net/http.serverHandler.ServeHTTP(0xc420138100, 0xc3d3e0, 0xc4287aa410, 0xc4336d50e0)
/usr/local/go/src/net/http/server.go:2202 +0x7d fp=0xc438085d28 sp=0xc438085ce0
net/http.(*conn).serve(0xc42badfc80, 0xc3de60, 0xc45161aec0)
/usr/local/go/src/net/http/server.go:1579 +0x4b7 fp=0xc438085f88 sp=0xc438085d28
runtime.goexit()
/usr/local/go/src/runtime/asm_amd64.s:2086 +0x1 fp=0xc438085f90 sp=0xc438085f88
created by net/http.(*Server).Serve
/usr/local/go/src/net/http/server.go:2293 +0x44d

[laiwei]

这是个好问题啊，看起来和http的统计接口有关，稍等看看

[shaofuzhang]

这个问题有什么后续嘛？我们也遇到这种问题，graph运行一段时间会出这个问题