fatal error: concurrent map iteration and map write

goroutine 96598 [running]:
runtime.throw(0xae2e82, 0x26)
/usr/local/go/src/runtime/panic.go:1116 +0x72 fp=0xc00044ec78 sp=0xc00044ec48 pc=0x434972
runtime.mapiternext(0xc00044ed60)
/usr/local/go/src/runtime/map.go:853 +0x552 fp=0xc00044ecf8 sp=0xc00044ec78 pc=0x40f822
runtime.mapiterinit(0xa22300, 0xc000297560, 0xc00044ed60)
/usr/local/go/src/runtime/map.go:843 +0x1c4 fp=0xc00044ed18 sp=0xc00044ecf8 pc=0x40f1d4
github.com/bilibili/discovery/model.copyInstance(0xc0001348f0, 0xc00000e098)
/data/discovery/model/instance.go:103 +0x192 fp=0xc00044edd0 sp=0xc00044ed18 pc=0x991862
github.com/bilibili/discovery/model.(*Apps).InstanceInfo(0xc000542390, 0x0, 0x0, 0x0, 0xc000000001, 0xc000186860, 0x0, 0x0)
/data/discovery/model/instance.go:195 +0x255 fp=0xc00044eef8 sp=0xc00044edd0 pc=0x992135
github.com/bilibili/discovery/registry.(*Registry).Fetch(0xc000195130, 0x0, 0x0, 0xc0002301f5, 0x3, 0xc0002301e6, 0xa, 0x0, 0x1, 0xc000134188, ...)
/data/discovery/registry/registry.go:176 +0x1b0 fp=0xc00044efb0 sp=0xc00044eef8 pc=0x9997b0
github.com/bilibili/discovery/registry.(*Registry).broadcast(0xc000195130, 0xc0002301f5, 0x3, 0xc0002301e6, 0xa)
/data/discovery/registry/registry.go:257 +0x5c7 fp=0xc00044f1a0 sp=0xc00044efb0 pc=0x99ad57
github.com/bilibili/discovery/registry.(*Registry).Set(0xc000195130, 0xc000274960, 0xd60115ec06a39)
/data/discovery/registry/registry.go:288 +0xde fp=0xc00044f218 sp=0xc00044f1a0 pc=0x99b03e
github.com/bilibili/discovery/discovery.(*Discovery).Set(0xc0002e1f80, 0xbb50e0, 0xc0002745a0, 0xc000274960, 0x0, 0x7c245c673aca)
/data/discovery/discovery/register.go:96 +0x40 fp=0xc00044f280 sp=0xc00044f218 pc=0x99dd70
github.com/bilibili/discovery/http.set(0xc0002745a0)