Golang致命错误:并发地图读取和地图写入 [英] Golang fatal error: concurrent map read and map write
问题描述
我正在用Go编写Minecraft服务器,当服务器受到2000多个连接的压力时,我会发生此崩溃:
I'm writing minecraft server in Go, when server is being stressed by 2000+ connections I get this crash:
致命错误:并发地图读取和地图写入/root/work/src/github.com/user/imoobler/limbo.go:78 + 0x351 由main.main/root/work/src/github.com/user/imoobler/limbo.go创建:33 + 0x368
fatal error: concurrent map read and map write/root/work/src/github.com/user/imoobler/limbo.go:78 +0x351 created by main.main /root/work/src/github.com/user/imoobler/limbo.go:33 +0x368
我的代码:
package main
import (
"log"
"net"
"bufio"
"time"
"math/rand"
"fmt"
)
var (
connCounter = 0
)
func main() {
InitConfig()
InitPackets()
port := int(config["port"].(float64))
ln, err := net.Listen("tcp", fmt.Sprintf(":%d", port))
if err != nil {
log.Fatal(err)
}
log.Println("Server launched on port", port)
go KeepAlive()
for {
conn, err := ln.Accept()
if err != nil {
log.Print(err)
} else {
connCounter+=1
go HandleConnection(conn, connCounter)
}
}
}
func KeepAlive() {
r := rand.New(rand.NewSource(15768735131534))
keepalive := &PacketPlayKeepAlive{
id: 0,
}
for {
for _, player := range players {
if player.state == PLAY {
id := int(r.Uint32())
keepalive.id = id
player.keepalive = id
player.WritePacket(keepalive)
}
}
time.Sleep(20000000000)
}
}
func HandleConnection(conn net.Conn, id int) {
log.Printf("%s connected.", conn.RemoteAddr().String())
player := &Player {
id: id,
conn: conn,
state: HANDSHAKING,
protocol: V1_10,
io: &ConnReadWrite{
rdr: bufio.NewReader(conn),
wtr: bufio.NewWriter(conn),
},
inaddr: InAddr{
"",
0,
},
name: "",
uuid: "d979912c-bb24-4f23-a6ac-c32985a1e5d3",
keepalive: 0,
}
for {
packet, err := player.ReadPacket()
if err != nil {
break
}
CallEvent("packetReceived", packet)
}
player.unregister()
conn.Close()
log.Printf("%s disconnected.", conn.RemoteAddr().String())
}
目前,服务器仅是"limbo".
For now server is only "limbo".
推荐答案
通常来说(没有访问发生错误的代码的权限),您可以选择几种方法.这是其中的两个:
Generally speaking (without having access to the code where the error occurs) you have a few options. Here are two of them:
使用sync.RWMutex{}
控制对地图的访问.如果您具有单次读写操作,而不是循环映射,请使用此选项.请参见 RWMutex
Control access to the map with sync.RWMutex{}
. Use this option if you have single reads and writes, not loops over the map. See RWMutex
这里有一个可以通过someMapMutex
访问someMap
的示例:
Here a sample with access control to someMap
via someMapMutex
:
var (
someMap = map[string]string{}
someMapMutex = sync.RWMutex{}
)
go func() {
someMapMutex.Lock()
someMap["key"] = "value"
someMapMutex.Unlock()
}()
someMapMutex.RLock()
v, ok := someMap["key"]
someMapMutex.RUnlock()
if !ok {
fmt.Println("key missing")
return
}
fmt.Println(v)
syncmap.Map
使用syncmap.Map{}
代替普通的map
.该地图已经解决了种族问题,但根据您的使用情况可能会更慢. syncmap.Map{}
的主要优点在于for循环.请参见同步地图
syncmap.Map
Use a syncmap.Map{}
instead of a normal map
. This map is already taking care of race issues but may be slower depending on your usage. syncmap.Map{}
s main advantage lies with for loops. See syncmap
var (
someMap = syncmap.Map{}
)
go func() {
someMap.Store("key", "value")
}()
v, ok := someMap.Load("key")
if !ok {
fmt.Println("key missing")
return
}
fmt.Println(v)
// with syncmap, looping over all keys is simple without locking the whole map for the entire loop
someMap.Range(func(key, value interface{}) bool {
// cast value to correct format
val, ok := value.(string)
if !ok {
// this will break iteration
return false
}
// do something with key/value
fmt.Println(key, val)
// this will continue iterating
return true
})
一般建议
您应该使用-race
选项测试服务器,然后消除它引发的所有竞争条件.这样一来,您就可以更轻松地在此类错误发生之前消除它们.
General Advice
You should test your server with -race
option and then eliminate all the race conditions it throws. That way you can easier eliminate such errors before they occur.
go run -race server.go
请参见 golang种族检测器
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