rfyiamcool/grpc-client-pool

grpc client pool for grpc-sidecar and grpc-proxy.

grpc-client-pool

grpc-client-pool's scenes are mainly about grpc-sidecar and grpc-proxy !

desc

Each grpc request contains PATH in http2 header, the path is fullMethod.

what is fullMethod ?

/api.v1.election.CandidateSvc/Register

what is serviceName ?

/api.v1.election.CandidateSvc

what is methodName ?

/Register

process

1. init grpc client pool
2. get grpc-client by grpc fullMethod/serviceName
3. use gprc invoke request/response.

grpc-client-pool's Issues

不支持protobuf吗

你好，请问个grpc负载均衡的问题

看了你这边的连接池给了我很大的帮助，但有一个问题我不是很明白
如下：是通过域名解析实现的一个简单的负载均衡，但我不是很明白grpc内部是怎么对多个连接进行管理的

func main() {
var svc = flag.String("service", "hello_service", "service name")
var reg = flag.String("reg", "http://192.168.127.135:2379", "register etcd address")
flag.Parse()
r := grpclb.NewResolver(*reg, *svc)
resolver.Register(r)

ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
defer cancel()
DefaultServiceConfig := `{"loadBalancingPolicy":"round_robin"}`
// authority是自己随便起的，不是必须的，但是r.Scheme()+"://authority/"+*svc这种格式是必须的
conn, err := grpc.DialContext(ctx, r.Scheme()+"://authority/"+*svc, grpc.WithInsecure(), grpc.WithDefaultServiceConfig(DefaultServiceConfig), grpc.WithBlock())
if err != nil {
    panic(err)
}

ticker := time.NewTicker(1000 * time.Millisecond)
client := pb.NewGreeterClient(conn)
for t := range ticker.C {
    resp, err := client.SayHello(context.Background(), &pb.HelloRequest{Name: "world " + strconv.Itoa(t.Second())})
    if err == nil {
        logrus.Infof("%v: Reply is %s\n", t, resp.Message)
    }
}

}`

connect to backend server err would cause many goroutines been stuck at client.go#L104

we integrate client.go into our api-gateway.
when our backend gRPC server become unavailable,
our api-gateway process's cpu&memory&goroutines all goes up.

the problem is that client.go uses grpc.Dial() with grpc.WithBlock(),
so when server goes down, every call to grpcpool.getConn() will take 3-second to finish,
causing more and more goroutines got stuck at client.go#L104