📖 Introduction
gnet
is an event-driven networking framework that is fast and lightweight. It makes direct epoll and kqueue syscalls rather than using the standard Go net package and works in a similar manner as netty and libuv, which makes gnet
achieve a much higher performance than Go net.
gnet
is not designed to displace the standard Go net package, but to create a networking server framework for Go that performs on par with Redis and Haproxy for networking packets handling.
gnet
sells itself as a high-performance, lightweight, non-blocking, event-driven networking framework written in pure Go which works on transport layer with TCP/UDP protocols and Unix Domain Socket , so it allows developers to implement their own protocols(HTTP, RPC, WebSocket, Redis, etc.) of application layer upon gnet
for building diversified network applications, for instance, you get an HTTP Server or Web Framework if you implement HTTP protocol upon gnet
while you have a Redis Server done with the implementation of Redis protocol upon gnet
and so on.
gnet
derives from the project: evio
while having a much higher performance and more features.
🚀 Features
- High-performance event-loop under networking model of multiple threads/goroutines
- Built-in goroutine pool powered by the library ants
- Built-in memory pool with bytes powered by the library bytebufferpool
- Lock-free during the entire runtime
- Concise and easy-to-use APIs
- Efficient, reusable and scalable memory buffer: Ring-Buffer
- Supporting multiple protocols/IPC mechanism:
TCP
,UDP
andUnix Domain Socket
- Supporting multiple load-balancing algorithms:
Round-Robin
,Source-Addr-Hash
andLeast-Connections
- Supporting two event-driven mechanisms:
epoll
on Linux andkqueue
on FreeBSD/DragonFly/Darwin - Supporting asynchronous write operation
- Flexible ticker event
- SO_REUSEPORT socket option
- Built-in multiple codecs to encode/decode network frames into/from TCP stream: LineBasedFrameCodec, DelimiterBasedFrameCodec, FixedLengthFrameCodec and LengthFieldBasedFrameCodec, referencing netty codec, also supporting customized codecs
- Supporting Windows platform with
event-driven mechanism of IOCPGo stdlib: net - Implementation of
gnet
Client
💡 Key Designs
Networking Model of Multiple Threads/Goroutines
Multiple Reactors
gnet
redesigns and implements a new built-in networking model of multiple threads/goroutines: 『multiple reactors』 which is also the default networking model of multiple threads in netty
, Here's the schematic diagram:
and it works as the following sequence diagram:
Multiple Reactors + Goroutine Pool
You may ask me a question: what if my business logic in EventHandler.React
contains some blocking code which leads to blocking in event-loop of gnet
, what is the solution for this kind of situation?
As you know, there is a most important tenet when writing code under gnet
: you should never block the event-loop goroutine in the EventHandler.React
, which is also the most important tenet in netty
, otherwise, it will result in a low throughput in your gnet
server.
And the solution to that could be found in the subsequent networking model of multiple threads/goroutines in gnet
: 『multiple reactors with thread/goroutine pool』which pulls you out from the blocking mire, it will construct a worker-pool with fixed capacity and put those blocking jobs in EventHandler.React
into the worker-pool to make the event-loop goroutines non-blocking.
The networking model:『multiple reactors with thread/goroutine pool』dissolves the blocking jobs by introducing a goroutine pool, as shown below:
and it works as the following sequence diagram:
gnet
implements the networking model:『multiple reactors with thread/goroutine pool』by the aid of a high-performance goroutine pool called ants that allows you to manage and recycle a massive number of goroutines in your concurrent programs, the full features and usages in ants
are documented here.
gnet
integrates ants
and provides the pool.goroutine.Default()
method that you can call to instantiate a ants
pool where you are able to put your blocking code logic and call the function gnet.Conn.AsyncWrite([]byte)
to send out data asynchronously after you finish the blocking process and get the output data, which makes the goroutine of event-loop non-blocking.
The details about integrating gnet
with ants
are shown here.
Reusable and auto-scaling Ring Buffer
There are two ring-buffers inside gnet
: inbound buffer and outbound buffer to buffer and manage inbound/outbound network data, ring-buffer inside gnet is designed and tuned to reuse memory and be auto-scaling on demand.
The purpose of implementing inbound and outbound ring-buffers in gnet
is to transfer the logic of buffering and managing network data based on application protocol upon TCP stream from business server to framework and unify the network data buffer, which minimizes the complexity of business code so that developers are able to concentrate on business logic instead of the underlying implementation.
🎉 Getting Started
Prerequisites
gnet
requires Go 1.9 or later.
Installation
go get -u github.com/panjf2000/gnet
gnet
is available as a Go module, with Go 1.11 Modules support (Go 1.11+), just simply import "github.com/panjf2000/gnet"
in your source code and go [build|run|test]
will download the necessary dependencies automatically.
Usage Examples
The detailed documentation is located in here: docs of gnet, but let's pass through the brief instructions first.
It is easy to create a network server with gnet
. All you have to do is just to make your implementation of gnet.EventHandler
interface and register your event-handler functions to it, then pass it to the gnet.Serve
function along with the binding address(es). Each connection is represented as a gnet.Conn
interface that is passed to various events to differentiate the clients. At any point you can close a connection or shutdown the server by return a Close
or Shutdown
action from an event function.
The simplest example to get you started playing with gnet
would be the echo server. So here you are, a simplest echo server upon gnet
that is listening on port 9000:
Echo server without blocking logic
Old version(<=v1.0.0-rc.4)
package mainimport ("log""github.com/panjf2000/gnet")type echoServer struct {*gnet.EventServer}func (es *echoServer) React(c gnet.Conn) (out []byte, action gnet.Action) {out = c.Read()c.ResetBuffer()return}func main() {echo := new(echoServer)log.Fatal(gnet.Serve(echo, "tcp://:9000", gnet.WithMulticore(true)))}
package mainimport ("log""github.com/panjf2000/gnet")type echoServer struct {*gnet.EventServer}func (es *echoServer) React(frame []byte, c gnet.Conn) (out []byte, action gnet.Action) {out = framereturn}func main() {echo := new(echoServer)log.Fatal(gnet.Serve(echo, "tcp://:9000", gnet.WithMulticore(true)))}
As you can see, this example of echo server only sets up the EventHandler.React
function where you commonly write your main business code and it will be called once the server receives input data from a client. What you should know is that the input parameter: frame
is a complete packet which has been decoded by the codec, as a general rule, you should implement the gnet
codec interface as the business codec to packet and unpacket TCP stream, but if you don't, your gnet
server is going to work with the default codec under the acquiescence, which means all data inculding latest data and previous data in buffer will be stored in the input parameter: frame
when EventHandler.React
is being triggered. The output data will be then encoded and sent back to that client by assigning the out
variable and returning it after your business code finish processing data(in this case, it just echo the data back).
Echo server with blocking logic
Old version(<=v1.0.0-rc.4)
package mainimport ("log""time""github.com/panjf2000/gnet""github.com/panjf2000/gnet/pool/goroutine")type echoServer struct {*gnet.EventServerpool *goroutine.Pool}func (es *echoServer) React(c gnet.Conn) (out []byte, action gnet.Action) {data := append([]byte{}, c.Read()...)c.ResetBuffer()// Use ants pool to unblock the event-loop._ = es.pool.Submit(func() {time.Sleep(1 * time.Second)c.AsyncWrite(data)})return}func main() {p := goroutine.Default()defer p.Release()echo := &echoServer{pool: p}log.Fatal(gnet.Serve(echo, "tcp://:9000", gnet.WithMulticore(true)))}
package mainimport ("log""time""github.com/panjf2000/gnet""github.com/panjf2000/gnet/pool/goroutine")type echoServer struct {*gnet.EventServerpool *goroutine.Pool}func (es *echoServer) React(frame []byte, c gnet.Conn) (out []byte, action gnet.Action) {data := append([]byte{}, frame...)// Use ants pool to unblock the event-loop._ = es.pool.Submit(func() {time.Sleep(1 * time.Second)c.AsyncWrite(data)})return}func main() {p := goroutine.Default()defer p.Release()echo := &echoServer{pool: p}log.Fatal(gnet.Serve(echo, "tcp://:9000", gnet.WithMulticore(true)))}
Like I said in the 『Multiple Reactors + Goroutine Pool』section, if there are blocking code in your business logic, then you ought to turn them into non-blocking code in any way, for instance, you can wrap them into a goroutine, but it will result in a massive amount of goroutines if massive traffic is passing through your server so I would suggest you utilize a goroutine pool like ants to manage those goroutines and reduce the cost of system resources.
All gnet examples:
TCP Echo Server
package mainimport ("flag""fmt""log""github.com/panjf2000/gnet")type echoServer struct {*gnet.EventServer}func (es *echoServer) OnInitComplete(srv gnet.Server) (action gnet.Action) {log.Printf("Echo server is listening on %s (multi-cores: %t, loops: %d)\n",srv.Addr.String(), srv.Multicore, srv.NumEventLoop)return}func (es *echoServer) React(frame []byte, c gnet.Conn) (out []byte, action gnet.Action) {// Echo synchronously.out = framereturn/*// Echo asynchronously.data := append([]byte{}, frame...)go func() {time.Sleep(time.Second)c.AsyncWrite(data)}()return*/}func main() {var port intvar multicore, reuseport bool// Example command: go run echo.go --port 9000 --multicore=true --reuseport=trueflag.IntVar(&port, "port", 9000, "--port 9000")flag.BoolVar(&multicore, "multicore", false, "--multicore true")flag.BoolVar(&reuseport, "reuseport", false, "--reuseport true")flag.Parse()echo := new(echoServer)log.Fatal(gnet.Serve(echo, fmt.Sprintf("tcp://:%d", port), gnet.WithMulticore(multicore), gnet.WithReusePort(reuseport)))}
UDP Echo Server
package mainimport ("flag""fmt""log""github.com/panjf2000/gnet")type echoServer struct {*gnet.EventServer}func (es *echoServer) OnInitComplete(srv gnet.Server) (action gnet.Action) {log.Printf("UDP Echo server is listening on %s (multi-cores: %t, loops: %d)\n",srv.Addr.String(), srv.Multicore, srv.NumEventLoop)return}func (es *echoServer) React(frame []byte, c gnet.Conn) (out []byte, action gnet.Action) {// Echo synchronously.out = framereturn/*// Echo asynchronously.data := append([]byte{}, frame...)go func() {time.Sleep(time.Second)c.SendTo(data)}()return*/}func main() {var port intvar multicore, reuseport bool// Example command: go run echo.go --port 9000 --multicore=true --reuseport=trueflag.IntVar(&port, "port", 9000, "--port 9000")flag.BoolVar(&multicore, "multicore", false, "--multicore true")flag.BoolVar(&reuseport, "reuseport", false, "--reuseport true")flag.Parse()echo := new(echoServer)log.Fatal(gnet.Serve(echo, fmt.Sprintf("udp://:%d", port), gnet.WithMulticore(multicore), gnet.WithReusePort(reuseport)))}
UDS Echo Server
package mainimport ("flag""fmt""log""github.com/panjf2000/gnet")type echoServer struct {*gnet.EventServer}func (es *echoServer) OnInitComplete(srv gnet.Server) (action gnet.Action) {log.Printf("Echo server is listening on %s (multi-cores: %t, loops: %d)\n",srv.Addr.String(), srv.Multicore, srv.NumEventLoop)return}func (es *echoServer) React(frame []byte, c gnet.Conn) (out []byte, action gnet.Action) {// Echo synchronously.out = framereturn/*// Echo asynchronously.data := append([]byte{}, frame...)go func() {time.Sleep(time.Second)c.AsyncWrite(data)}()return*/}func main() {var addr stringvar multicore bool// Example command: go run echo.go --sock echo.sock --multicore=trueflag.StringVar(&addr, "sock", "echo.sock", "--port 9000")flag.BoolVar(&multicore, "multicore", false, "--multicore true")flag.Parse()echo := new(echoServer)log.Fatal(gnet.Serve(echo, fmt.Sprintf("unix://%s", addr), gnet.WithMulticore(multicore)))}
HTTP Server
package mainimport ("flag""fmt""log""strconv""strings""time""unsafe""github.com/panjf2000/gnet")var res stringtype request struct {proto, method stringpath, query stringhead, body stringremoteAddr string}type httpServer struct {*gnet.EventServer}var (errMsg = "Internal Server Error"errMsgBytes = []byte(errMsg))type httpCodec struct {req request}func (hc *httpCodec) Encode(c gnet.Conn, buf []byte) (out []byte, err error) {if c.Context() == nil {return buf, nil}return appendResp(out, "500 Error", "", errMsg+"\n"), nil}func (hc *httpCodec) Decode(c gnet.Conn) (out []byte, err error) {buf := c.Read()c.ResetBuffer()// process the pipelinevar leftover []bytepipeline:leftover, err = parseReq(buf, &hc.req)// bad thing happenedif err != nil {c.SetContext(err)return nil, err} else if len(leftover) == len(buf) {// request not ready, yetreturn}out = appendHandle(out, res)buf = leftovergoto pipeline}func (hs *httpServer) OnInitComplete(srv gnet.Server) (action gnet.Action) {log.Printf("HTTP server is listening on %s (multi-cores: %t, loops: %d)\n",srv.Addr.String(), srv.Multicore, srv.NumEventLoop)return}func (hs *httpServer) React(frame []byte, c gnet.Conn) (out []byte, action gnet.Action) {if c.Context() != nil {// bad thing happenedout = errMsgBytesaction = gnet.Closereturn}// handle the requestout = framereturn}func main() {var port intvar multicore bool// Example command: go run http.go --port 8080 --multicore=trueflag.IntVar(&port, "port", 8080, "server port")flag.BoolVar(&multicore, "multicore", true, "multicore")flag.Parse()res = "Hello World!\r\n"http := new(httpServer)hc := new(httpCodec)// Start serving!log.Fatal(gnet.Serve(http, fmt.Sprintf("tcp://:%d", port), gnet.WithMulticore(multicore), gnet.WithCodec(hc)))}// appendHandle handles the incoming request and appends the response to// the provided bytes, which is then returned to the caller.func appendHandle(b []byte, res string) []byte {return appendResp(b, "200 OK", "", res)}// appendResp will append a valid http response to the provide bytes.// The status param should be the code plus text such as "200 OK".// The head parameter should be a series of lines ending with "\r\n" or empty.func appendResp(b []byte, status, head, body string) []byte {b = append(b, "HTTP/1.1"...)b = append(b, ' ')b = append(b, status...)b = append(b, '\r', '\n')b = append(b, "Server: gnet\r\n"...)b = append(b, "Date: "...)b = time.Now().AppendFormat(b, "Mon, 02 Jan 2006 15:04:05 GMT")b = append(b, '\r', '\n')if len(body) > 0 {b = append(b, "Content-Length: "...)b = strconv.AppendInt(b, int64(len(body)), 10)b = append(b, '\r', '\n')}b = append(b, head...)b = append(b, '\r', '\n')if len(body) > 0 {b = append(b, body...)}return b}func b2s(b []byte) string {return *(*string)(unsafe.Pointer(&b))}// parseReq is a very simple http request parser. This operation// waits for the entire payload to be buffered before returning a// valid request.func parseReq(data []byte, req *request) (leftover []byte, err error) {sdata := b2s(data)var i, s intvar head stringvar clen intq := -1// method, path, proto linefor ; i < len(sdata); i++ {if sdata[i] == ' ' {req.method = sdata[s:i]for i, s = i+1, i+1; i < len(sdata); i++ {if sdata[i] == '?' && q == -1 {q = i - s} else if sdata[i] == ' ' {if q != -1 {req.path = sdata[s:q]req.query = req.path[q+1 : i]} else {req.path = sdata[s:i]}for i, s = i+1, i+1; i < len(sdata); i++ {if sdata[i] == '\n' && sdata[i-1] == '\r' {req.proto = sdata[s:i]i, s = i+1, i+1break}}break}}break}}if req.proto == "" {return data, fmt.Errorf("malformed request")}head = sdata[:s]for ; i < len(sdata); i++ {if i > 1 && sdata[i] == '\n' && sdata[i-1] == '\r' {line := sdata[s : i-1]s = i + 1if line == "" {req.head = sdata[len(head)+2 : i+1]i++if clen > 0 {if len(sdata[i:]) < clen {break}req.body = sdata[i : i+clen]i += clen}return data[i:], nil}if strings.HasPrefix(line, "Content-Length:") {n, err := strconv.ParseInt(strings.TrimSpace(line[len("Content-Length:"):]), 10, 64)if err == nil {clen = int(n)}}}}// not enough datareturn data, nil}
Push Server
package mainimport ("flag""fmt""log""sync""time""github.com/panjf2000/gnet")type pushServer struct {*gnet.EventServertick time.DurationconnectedSockets sync.Map}func (ps *pushServer) OnInitComplete(srv gnet.Server) (action gnet.Action) {log.Printf("Push server is listening on %s (multi-cores: %t, loops: %d), "+"pushing data every %s ...\n", srv.Addr.String(), srv.Multicore, srv.NumEventLoop, ps.tick.String())return}func (ps *pushServer) OnOpened(c gnet.Conn) (out []byte, action gnet.Action) {log.Printf("Socket with addr: %s has been opened...\n", c.RemoteAddr().String())ps.connectedSockets.Store(c.RemoteAddr().String(), c)return}func (ps *pushServer) OnClosed(c gnet.Conn, err error) (action gnet.Action) {log.Printf("Socket with addr: %s is closing...\n", c.RemoteAddr().String())ps.connectedSockets.Delete(c.RemoteAddr().String())return}func (ps *pushServer) Tick() (delay time.Duration, action gnet.Action) {log.Println("It's time to push data to clients!!!")ps.connectedSockets.Range(func(key, value interface{}) bool {addr := key.(string)c := value.(gnet.Conn)c.AsyncWrite([]byte(fmt.Sprintf("heart beating to %s\n", addr)))return true})delay = ps.tickreturn}func (ps *pushServer) React(frame []byte, c gnet.Conn) (out []byte, action gnet.Action) {out = framereturn}func main() {var port intvar multicore boolvar interval time.Durationvar ticker bool// Example command: go run push.go --port 9000 --tick 1s --multicore=trueflag.IntVar(&port, "port", 9000, "server port")flag.BoolVar(&multicore, "multicore", true, "multicore")flag.DurationVar(&interval, "tick", 0, "pushing tick")flag.Parse()if interval > 0 {ticker = true}push := &pushServer{tick: interval}log.Fatal(gnet.Serve(push, fmt.Sprintf("tcp://:%d", port), gnet.WithMulticore(multicore), gnet.WithTicker(ticker)))}
Codec Client/Server
Client:
// Reference https://github.com/smallnest/goframe/blob/master/_examples/goclient/client.gopackage mainimport ("encoding/binary""fmt""net""github.com/smallnest/goframe")func main() {conn, err := net.Dial("tcp", "127.0.0.1:9000")if err != nil {panic(err)}defer conn.Close()encoderConfig := goframe.EncoderConfig{ByteOrder: binary.BigEndian,LengthFieldLength: 4,LengthAdjustment: 0,LengthIncludesLengthFieldLength: false,}decoderConfig := goframe.DecoderConfig{ByteOrder: binary.BigEndian,LengthFieldOffset: 0,LengthFieldLength: 4,LengthAdjustment: 0,InitialBytesToStrip: 4,}fc := goframe.NewLengthFieldBasedFrameConn(encoderConfig, decoderConfig, conn)err = fc.WriteFrame([]byte("hello"))if err != nil {panic(err)}err = fc.WriteFrame([]byte("world"))if err != nil {panic(err)}buf, err := fc.ReadFrame()if err != nil {panic(err)}fmt.Println("received: ", string(buf))buf, err = fc.ReadFrame()if err != nil {panic(err)}fmt.Println("received: ", string(buf))}
Server:
package mainimport ("encoding/binary""flag""fmt""log""time""github.com/panjf2000/gnet""github.com/panjf2000/gnet/pool/goroutine")type codecServer struct {*gnet.EventServeraddr stringmulticore boolasync boolcodec gnet.ICodecworkerPool *goroutine.Pool}func (cs *codecServer) OnInitComplete(srv gnet.Server) (action gnet.Action) {log.Printf("Test codec server is listening on %s (multi-cores: %t, loops: %d)\n",srv.Addr.String(), srv.Multicore, srv.NumEventLoop)return}func (cs *codecServer) React(frame []byte, c gnet.Conn) (out []byte, action gnet.Action) {if cs.async {data := append([]byte{}, frame...)_ = cs.workerPool.Submit(func() {c.AsyncWrite(data)})return}out = framereturn}func testCodecServe(addr string, multicore, async bool, codec gnet.ICodec) {var err errorif codec == nil {encoderConfig := gnet.EncoderConfig{ByteOrder: binary.BigEndian,LengthFieldLength: 4,LengthAdjustment: 0,LengthIncludesLengthFieldLength: false,}decoderConfig := gnet.DecoderConfig{ByteOrder: binary.BigEndian,LengthFieldOffset: 0,LengthFieldLength: 4,LengthAdjustment: 0,InitialBytesToStrip: 4,}codec = gnet.NewLengthFieldBasedFrameCodec(encoderConfig, decoderConfig)}cs := &codecServer{addr: addr, multicore: multicore, async: async, codec: codec, workerPool: goroutine.Default()}err = gnet.Serve(cs, addr, gnet.WithMulticore(multicore), gnet.WithTCPKeepAlive(time.Minute*5), gnet.WithCodec(codec))if err != nil {panic(err)}}func main() {var port intvar multicore bool// Example command: go run server.go --port 9000 --multicore=trueflag.IntVar(&port, "port", 9000, "server port")flag.BoolVar(&multicore, "multicore", true, "multicore")flag.Parse()addr := fmt.Sprintf("tcp://:%d", port)testCodecServe(addr, multicore, false, nil)}
Custom Codec Demo with Client/Server
protocol intro:
// CustomLengthFieldProtocol : custom protocol// custom protocol header contains Version, ActionType and DataLength fields// its payload is Data fieldtype CustomLengthFieldProtocol struct {Version uint16ActionType uint16DataLength uint32Data []byte}// Encode ...func (cc *CustomLengthFieldProtocol) Encode(c gnet.Conn, buf []byte) ([]byte, error) {result := make([]byte, 0)buffer := bytes.NewBuffer(result)// take out the param that `React()` event saved.item := c.Context().(CustomLengthFieldProtocol)if err := binary.Write(buffer, binary.BigEndian, item.Version); err != nil {s := fmt.Sprintf("Pack version error , %v", err)return nil, errors.New(s)}if err := binary.Write(buffer, binary.BigEndian, item.ActionType); err != nil {s := fmt.Sprintf("Pack type error , %v", err)return nil, errors.New(s)}dataLen := uint32(len(buf))if err := binary.Write(buffer, binary.BigEndian, dataLen); err != nil {s := fmt.Sprintf("Pack datalength error , %v", err)return nil, errors.New(s)}if dataLen > 0 {if err := binary.Write(buffer, binary.BigEndian, buf); err != nil {s := fmt.Sprintf("Pack data error , %v", err)return nil, errors.New(s)}}return buffer.Bytes(), nil}// Decode ...func (cc *CustomLengthFieldProtocol) Decode(c gnet.Conn) ([]byte, error) {// parse headerheaderLen := DefaultHeadLength // uint16+uint16+uint32if size, header := c.ReadN(headerLen); size == headerLen {byteBuffer := bytes.NewBuffer(header)var pbVersion, actionType uint16var dataLength uint32binary.Read(byteBuffer, binary.BigEndian, &pbVersion)binary.Read(byteBuffer, binary.BigEndian, &actionType)binary.Read(byteBuffer, binary.BigEndian, &dataLength)// to check the protocol version and actionType,// reset buffer if the version or actionType is not correctif pbVersion != DefaultProtocolVersion || isCorrectAction(actionType) == false {c.ResetBuffer()log.Println("not normal protocol:", pbVersion, DefaultProtocolVersion, actionType, dataLength)return nil, errors.New("not normal protocol")}// parse payloaddataLen := int(dataLength) // max int32 can contain 210MB payloadprotocolLen := headerLen + dataLenif dataSize, data := c.ReadN(protocolLen); dataSize == protocolLen {c.ShiftN(protocolLen)// log.Println("parse success:", data, dataSize)// return the payload of the datareturn data[headerLen:], nil}// log.Println("not enough payload data:", dataLen, protocolLen, dataSize)return nil, errors.New("not enough payload data")}// log.Println("not enough header data:", size)return nil, errors.New("not enough header data")}
Client/Server: Check out the source code.
For more details, check out here: all examples of gnet.
I/O Events
Current supported I/O events in gnet
:
EventHandler.OnInitComplete
fires when the server has been initialized and ready to accept new connections.EventHandler.OnOpened
fires once a connection has been opened.EventHandler.OnClosed
fires after a connection has been closed.EventHandler.React
fires when the server receives inbound data from a socket/connection. (usually it is where you write the code of business logic)EventHandler.Tick
fires right after the server starts and then fires every specified interval.EventHandler.PreWrite
fires just before any data has been written to client.
Ticker
The EventHandler.Tick
event fires ticks at a specified interval.
The first tick fires right after the gnet server starts up and if you intend to set up a ticker event, don't forget to pass an option: gnet.WithTicker(true)
to gnet.Serve
.
events.Tick = func() (delay time.Duration, action Action){log.Printf("tick")delay = time.Secondreturn}
UDP
gnet
supports UDP protocol so the gnet.Serve
method can bind to UDP addresses.
- All incoming and outgoing packets will not be buffered but read and sent directly, which means all functions of
gnet.Conn
that manipulate the internal buffers are not available; users should use theframe []byte
from thegnet.React(frame []byte, c gnet.Conn)
as the UDP packet instead calling functions ofgnet.Conn
, likec.Read()
,c.ResetBuffer()
,c.BufferLength()
and so on, to process data. - The
EventHandler.OnOpened
andEventHandler.OnClosed
events are not available for UDP sockets, only theReact
event. - The UDP equivalents of
AsyncWrite([]byte)
in TCP isSendTo([]byte)
.
Unix Domain Socket
gnet
also supports UDS(Unix Domain Socket), just pass the UDS addresses like "unix://xxx" to the gnet.Serve
method and you could play with it.
It is nothing different from making use of TCP when doing stuff with UDS, so the gnet
UDS servers are able to leverage all event functions which are available under TCP protocol.
Multi-threads
The gnet.WithMulticore(true)
indicates whether the server will be effectively created with multi-cores, if so, then you must take care of synchronizing memory between all event callbacks, otherwise, it will run the server with a single thread. The number of threads in the server will be automatically assigned to the value of runtime.NumCPU()
.
Load Balancing
gnet
currently supports three load balancing algorithms: Round-Robin
, Source-Addr-Hash
and Least-Connections
, you are able to decide which algorithm to use by passing the functional option LB
(RoundRobin/LeastConnections/SourceAddrHash) to gnet.Serve
.
If the load balancing algorithm is not specified explicitly, gnet
will use Round-Robin
by default.
SO_REUSEPORT
gnet
server is able to utilize the SO_REUSEPORT option which allows multiple sockets on the same host to bind to the same port and the OS kernel takes care of the load balancing for you, it wakes one socket per connect
event coming to resolved the thundering herd
.
By default, gnet
is not going to be haunted by the thundering herd
under its networking model:『multiple reactors』which gets only one main reactor to listen on "address:port" and accept new sockets. So this SO_REUSEPORT
option is trivial in gnet
but note that it will fall back to the old networking model of evio
when you enable the SO_REUSEPORT
option.
Just use functional options to set up SO_REUSEPORT
and you can enjoy this feature:
gnet.Serve(events, "tcp://:9000", gnet.WithMulticore(true), gnet.WithReusePort(true)))
Multiple built-in codecs for TCP stream
There are multiple built-in codecs in gnet
which allow you to encode/decode frames into/from TCP stream.
So far gnet
has four kinds of built-in codecs: LineBasedFrameCodec, DelimiterBasedFrameCodec, FixedLengthFrameCodec and LengthFieldBasedFrameCodec, which generally meets most scenarios, but still gnet
allows users to customize their own codecs in their gnet
servers by implementing the interface gnet.ICodec and replacing the default codec in gnet
with customized codec via functional options.
Here is an example with codec, showing you how to leverage codec to encode/decode network frames into/from TCP stream.
📊 Performance
Benchmarks on TechEmpower
# Hardware EnvironmentCPU: 28 HT Cores Intel(R) Xeon(R) Gold 5120 CPU @ 2.20GHzMem: 32GB RAMOS : Ubuntu 18.04.3 4.15.0-88-generic #88-UbuntuNet: Switched 10-gigabit ethernetGo : go1.14.x linux/amd64
This is the top 50 on the framework ranking of all programming languages consists of a total of 422 frameworks from all over the world where gnet
is the runner-up.
This is the full framework ranking of Go and gnet
tops all the other frameworks, which makes gnet
the fastest networking framework in Go.
To see the full ranking list, visit TechEmpower Plaintext Benchmark.
Contrasts to the similar networking libraries
On Linux (epoll)
Test Environment
# Machine informationOS : Ubuntu 20.04/x86_64CPU : 8 processors, AMD EPYC 7K62 48-Core ProcessorMemory : 16.0 GiB# Go version and settingsGo Version : go1.15.7 linux/amd64GOMAXPROCS : 8# Netwokr settingsTCP connections : 300Test duration : 30s
Echo Server
HTTP Server
On FreeBSD (kqueue)
Test Environment
# Machine informationOS : macOS Catalina 10.15.7/x86_64CPU : 6-Core Intel Core i7Memory : 16.0 GiB# Go version and configurationsGo Version : go1.15.7 darwin/amd64GOMAXPROCS : 12# Netwokr settingsTCP connections : 100Test duration : 20s
Echo Server
HTTP Server
️🚨 License
Source code in gnet
is available under the MIT License.
👏 Contributors
Please read the Contributing Guidelines before opening a PR and thank you to all the developers who already made contributions to gnet
!
🙏 Acknowledgments
⚓ Relevant Articles
- A Million WebSockets and Go
- Going Infinite, handling 1M websockets connections in Go
- Go netpoller 原生网络模型之源码全面揭秘
- gnet: 一个轻量级且高性能的 Golang 网络库
- 最快的 Go 网络框架 gnet 来啦!
- 字节跳动在 Go 网络库上的实践
🎡 User cases
The following companies/organizations use gnet
as the underlying network service in production.





If your projects are also using gnet
, feel free to open a pull request refreshing this list of user cases.
💰 Backers
Support us with a monthly donation and help us continue our activities.
💎 Sponsors
Become a bronze sponsor with a monthly donation of $10 and get your logo on our README on Github.
☕️ Buy me a coffee
Please be sure to leave your name, Github account or other social media accounts when you donate by the following means so that I can add it to the list of donors as a token of my appreciation.
💴 Donors
💵 Paid Support
If you need a tailored version of gnet
and want the author to help develop it, or bug fix/fast resolution/consultation which takes a lot of effort, you can request paid support here.
🔑 JetBrains OS licenses
gnet
had been being developed with GoLand
IDE under the free JetBrains Open Source license(s) granted by JetBrains s.r.o., hence I would like to express my thanks here.
