fatal error: concurrent map read and map write

[wongoo]

What happened:

detail see: https://travis-ci.org/apache/dubbo-go/jobs/565782895

2019-07-31T03:20:27.734Z	DEBUG	directory/directory.go:126	update service name: dubbo://:@:/TEST2?cluster=mock&group=group2!
fatal error: concurrent map read and map write
goroutine 12 [running]:
runtime.throw(0x7b7b34, 0x21)
	/home/travis/.gimme/versions/go1.12.linux.amd64/src/runtime/panic.go:617 +0x72 fp=0xc0000b36f0 sp=0xc0000b36c0 pc=0x42e932
runtime.mapaccess1_faststr(0x774340, 0xc0000863c0, 0x7ad44f, 0x5, 0x1)
	/home/travis/.gimme/versions/go1.12.linux.amd64/src/runtime/map_faststr.go:21 +0x464 fp=0xc0000b3760 sp=0xc0000b36f0 pc=0x413a44
net/url.Values.Get(...)
	/home/travis/.gimme/versions/go1.12.linux.amd64/src/net/url/url.go:838
github.com/apache/dubbo-go/common.URL.GetParam(...)
	/home/travis/gopath/src/github.com/apache/dubbo-go/common/url.go:286
github.com/apache/dubbo-go/registry/directory.(*registryDirectory).toGroupInvokers(0xc000146000, 0x7ad422, 0x5, 0x7acd31)
	/home/travis/gopath/src/github.com/apache/dubbo-go/registry/directory/directory.go:164 +0x956 fp=0xc0000b3d10 sp=0xc0000b3760 pc=0x6ef9b6
github.com/apache/dubbo-go/registry/directory.(*registryDirectory).refreshInvokers(0xc000146000, 0xc000129500)
	/home/travis/gopath/src/github.com/apache/dubbo-go/registry/directory/directory.go:145 +0x1b3 fp=0xc0000b3f80 sp=0xc0000b3d10 pc=0x6eeeb3
github.com/apache/dubbo-go/registry/directory.(*registryDirectory).update(0xc000146000, 0xc000129500)
	/home/travis/gopath/src/github.com/apache/dubbo-go/registry/directory/directory.go:128 +0x187 fp=0xc0000b3fd0 sp=0xc0000b3f80 pc=0x6eec97
runtime.goexit()
	/home/travis/.gimme/versions/go1.12.linux.amd64/src/runtime/asm_amd64.s:1337 +0x1 fp=0xc0000b3fd8 sp=0xc0000b3fd0 pc=0x45ccf1
created by github.com/apache/dubbo-go/registry/directory.(*registryDirectory).Subscribe
	/home/travis/gopath/src/github.com/apache/dubbo-go/registry/directory/directory.go:110 +0x3a

[gaoxinge]

Although pr #172 has been raised, there is still concurrent map read and write error (travis ci) when testing directory. @hxmhlt @AlexStocks

fatal error: concurrent map iteration and map write

goroutine 24 [running]:
runtime.throw(0x7c2d8e, 0x26)
	/home/travis/.gimme/versions/go1.12.linux.amd64/src/runtime/panic.go:617 +0x72 fp=0xc0000993c8 sp=0xc000099398 pc=0x42e932
runtime.mapiternext(0xc000099590)
	/home/travis/.gimme/versions/go1.12.linux.amd64/src/runtime/map.go:860 +0x520 fp=0xc000099450 sp=0xc0000993c8 pc=0x4104e0
runtime.mapiterinit(0x77c7a0, 0xc00010a390, 0xc000099590)
	/home/travis/.gimme/versions/go1.12.linux.amd64/src/runtime/map.go:850 +0x1c9 fp=0xc000099470 sp=0xc000099450 pc=0x40fec9
net/url.Values.Encode(0xc00010a390, 0x13, 0xc000057670)
	/home/travis/.gimme/versions/go1.12.linux.amd64/src/net/url/url.go:919 +0xd5 fp=0xc000099600 sp=0xc000099470 pc=0x5b39b5
github.com/apache/dubbo-go/common.URL.String(0x7b626a, 0x5, 0x7b5b71, 0x1, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, ...)
	/home/travis/gopath/src/github.com/apache/dubbo-go/common/url.go:240 +0x20d fp=0xc0000996e0 sp=0xc000099600 pc=0x6d69fd
github.com/apache/dubbo-go/common.(*URL).String(0xc000105d40, 0x7ce330, 0xc0000e0240)
	<autogenerated>:1 +0x8a fp=0xc0000998a0 sp=0xc0000996e0 pc=0x6d8a9a
fmt.(*pp).handleMethods(0xc0000e0240, 0x73, 0x1)
	/home/travis/.gimme/versions/go1.12.linux.amd64/src/fmt/print.go:616 +0x29b fp=0xc000099940 sp=0xc0000998a0 pc=0x4b939b
fmt.(*pp).printArg(0xc0000e0240, 0x7a6c80, 0xc000105d40, 0x73)
	/home/travis/.gimme/versions/go1.12.linux.amd64/src/fmt/print.go:699 +0x20a fp=0xc0000999d8 sp=0xc000099940 pc=0x4b981a
fmt.(*pp).doPrintf(0xc0000e0240, 0x7c130c, 0x22, 0xc000099b50, 0x2, 0x2)
	/home/travis/.gimme/versions/go1.12.linux.amd64/src/fmt/print.go:1016 +0x152 fp=0xc000099ac0 sp=0xc0000999d8 pc=0x4bd202
fmt.Sprintf(0x7c130c, 0x22, 0xc000057b50, 0x2, 0x2, 0xc00007f380, 0xc000044b80)
	/home/travis/.gimme/versions/go1.12.linux.amd64/src/fmt/print.go:214 +0x66 fp=0xc000099b18 sp=0xc000099ac0 pc=0x4b62d6
github.com/apache/dubbo-go/registry.ServiceEvent.String(...)
	/home/travis/gopath/src/github.com/apache/dubbo-go/registry/event.go:45
github.com/apache/dubbo-go/registry.(*ServiceEvent).String(0xc0001222a0, 0x7ce330, 0xc0000e0000)
	<autogenerated>:1 +0x109 fp=0xc000099c58 sp=0xc000099b18 pc=0x6da759
fmt.(*pp).handleMethods(0xc0000e0000, 0x73, 0x1)
	/home/travis/.gimme/versions/go1.12.linux.amd64/src/fmt/print.go:616 +0x29b fp=0xc000099cf8 sp=0xc000099c58 pc=0x4b939b
fmt.(*pp).printArg(0xc0000e0000, 0x74afe0, 0xc0001222a0, 0x73)
	/home/travis/.gimme/versions/go1.12.linux.amd64/src/fmt/print.go:699 +0x20a fp=0xc000099d90 sp=0xc000099cf8 pc=0x4b981a
fmt.(*pp).doPrintf(0xc0000e0000, 0x7bdef7, 0x1b, 0xc00002ff60, 0x1, 0x1)
	/home/travis/.gimme/versions/go1.12.linux.amd64/src/fmt/print.go:1016 +0x152 fp=0xc000099e78 sp=0xc000099d90 pc=0x4bd202
fmt.Sprintf(0x7bdef7, 0x1b, 0xc00002ff60, 0x1, 0x1, 0x0, 0x45ccf1)
	/home/travis/.gimme/versions/go1.12.linux.amd64/src/fmt/print.go:214 +0x66 fp=0xc000099ed0 sp=0xc000099e78 pc=0x4b62d6
go.uber.org/zap.(*SugaredLogger).log(0xc000010060, 0xff, 0x7bdef7, 0x1b, 0xc00002ff60, 0x1, 0x1, 0x0, 0x0, 0x0)
	/home/travis/gopath/pkg/mod/go.uber.org/[email protected]/sugar.go:230 +0x128 fp=0xc000099f20 sp=0xc000099ed0 pc=0x6acda8
go.uber.org/zap.(*SugaredLogger).Debugf(0xc000010060, 0x7bdef7, 0x1b, 0xc00002ff60, 0x1, 0x1)
	/home/travis/gopath/pkg/mod/go.uber.org/[email protected]/sugar.go:133 +0x79 fp=0xc000099f80 sp=0xc000099f20 pc=0x6aca59
github.com/apache/dubbo-go/common/logger.Debugf(...)
	/home/travis/gopath/src/github.com/apache/dubbo-go/common/logger/logging.go:42
github.com/apache/dubbo-go/registry/directory.(*registryDirectory).update(0xc00011e070, 0xc0001222a0)
	/home/travis/gopath/src/github.com/apache/dubbo-go/registry/directory/directory.go:122 +0xc9 fp=0xc000099fd0 sp=0xc000099f80 pc=0x6f5669
runtime.goexit()
	/home/travis/.gimme/versions/go1.12.linux.amd64/src/runtime/asm_amd64.s:1337 +0x1 fp=0xc000099fd8 sp=0xc000099fd0 pc=0x45ccf1
created by github.com/apache/dubbo-go/registry/directory.(*registryDirectory).Subscribe
	/home/travis/gopath/src/github.com/apache/dubbo-go/registry/directory/directory.go:109 +0x395

It seems that it is not safe when we calling url.String method.

[hxmhlt]

resolved by #201