https server will not be impacted by the MaxConcurrentStreams settin…

go.mod

@@ -40,6 +40,7 @@ require (
 
 require (
 	cloud.google.com/go v0.81.0 // indirect
+	github.com/BurntSushi/toml v1.1.0 // indirect
 	github.com/beorn7/perks v1.0.1 // indirect
 	github.com/cenkalti/backoff/v4 v4.1.1 // indirect
 	github.com/cespare/xxhash/v2 v2.1.2 // indirect
@@ -68,7 +69,7 @@ require (
 	github.com/sirupsen/logrus v1.8.1 // indirect
 	github.com/soheilhy/cmux v0.1.5 // indirect
 	github.com/spf13/pflag v1.0.5 // indirect
-	github.com/stretchr/testify v1.7.0 // indirect
+	github.com/stretchr/testify v1.7.1 // indirect
 	github.com/tmc/grpc-websocket-proxy v0.0.0-20201229170055-e5319fda7802 // indirect
 	github.com/xiang90/probing v0.0.0-20190116061207-43a291ad63a2 // indirect
 	go.opentelemetry.io/contrib/instrumentation/google.golang.org/grpc/otelgrpc v0.26.1 // indirect

go.sum

@@ -37,8 +37,9 @@ cloud.google.com/go/storage v1.6.0/go.mod h1:N7U0C8pVQ/+NIKOBQyamJIeKQKkZ+mxpohl
 cloud.google.com/go/storage v1.8.0/go.mod h1:Wv1Oy7z6Yz3DshWRJFhqM/UCfaWIRTdp0RXyy7KQOVs=
 cloud.google.com/go/storage v1.10.0/go.mod h1:FLPqc6j+Ki4BU591ie1oL6qBQGu2Bl/tZ9ullr3+Kg0=
 dmitri.shuralyov.com/gpu/mtl v0.0.0-20190408044501-666a987793e9/go.mod h1:H6x//7gZCb22OMCxBHrMx7a5I7Hp++hsVxbQ4BYO7hU=
-github.com/BurntSushi/toml v0.3.1 h1:WXkYYl6Yr3qBf1K79EBnL4mak0OimBfB0XUf9Vl28OQ=
 github.com/BurntSushi/toml v0.3.1/go.mod h1:xHWCNGjB5oqiDr8zfno3MHue2Ht5sIBksp03qcyfWMU=
+github.com/BurntSushi/toml v1.1.0 h1:ksErzDEI1khOiGPgpwuI7x2ebx/uXQNw7xJpn9Eq1+I=
+github.com/BurntSushi/toml v1.1.0/go.mod h1:CxXYINrC8qIiEnFrOxCa7Jy5BFHlXnUU2pbicEuybxQ=
 github.com/BurntSushi/xgb v0.0.0-20160522181843-27f122750802/go.mod h1:IVnqGOEym/WlBOVXweHU+Q+/VP0lqqI8lqeDx9IjBqo=
 github.com/OneOfOne/xxhash v1.2.2/go.mod h1:HSdplMjZKSmBqAxg5vPj2TmRDmfkzw+cTzAElWljhcU=
 github.com/alecthomas/template v0.0.0-20160405071501-a0175ee3bccc/go.mod h1:LOuyumcjzFXgccqObfd/Ljyb9UuFJ6TxHnclSeseNhc=
@@ -297,8 +298,9 @@ github.com/stretchr/testify v1.3.0/go.mod h1:M5WIy9Dh21IEIfnGCwXGc5bZfKNJtfHm1UV
 github.com/stretchr/testify v1.4.0/go.mod h1:j7eGeouHqKxXV5pUuKE4zz7dFj8WfuZ+81PSLYec5m4=
 github.com/stretchr/testify v1.5.1/go.mod h1:5W2xD1RspED5o8YsWQXVCued0rvSQ+mT+I5cxcmMvtA=
 github.com/stretchr/testify v1.6.1/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
-github.com/stretchr/testify v1.7.0 h1:nwc3DEeHmmLAfoZucVR881uASk0Mfjw8xYJ99tb5CcY=
 github.com/stretchr/testify v1.7.0/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
+github.com/stretchr/testify v1.7.1 h1:5TQK59W5E3v0r2duFAb7P95B6hEeOyEnHRa8MjYSMTY=
+github.com/stretchr/testify v1.7.1/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
 github.com/tmc/grpc-websocket-proxy v0.0.0-20201229170055-e5319fda7802 h1:uruHq4dN7GR16kFc5fp3d1RIYzJW5onx8Ybykw2YQFA=
 github.com/tmc/grpc-websocket-proxy v0.0.0-20201229170055-e5319fda7802/go.mod h1:ncp9v5uamzpCO7NfCPTXjqaC+bZgJeR0sMTm6dMHP7U=
 github.com/xiang90/probing v0.0.0-20190116061207-43a291ad63a2 h1:eY9dn8+vbi4tKz5Qo6v2eYzo7kUS51QINcR5jNpbZS8=

pkg/flags/int.go

@@ -0,0 +1,50 @@
+// Copyright 2018 The etcd Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package flags
+
+import (
+	"flag"
+	"fmt"
+	"strconv"
+)
+
+type uint32Value uint32
+
+func NewUint32Value(s string) *uint32Value {
+	var u uint32Value
+	if s == "" || s == "0" {
+		return &u
+	}
+	if err := u.Set(s); err != nil {
+		panic(fmt.Sprintf("new uint32Value should never fail: %v", err))
+	}
+	return &u
+}
+
+func (i *uint32Value) Set(s string) error {
+	v, err := strconv.ParseUint(s, 0, 32)
+	*i = uint32Value(v)
+	return err
+}
+func (i *uint32Value) Type() string {
+	return "uint32"
+}
+func (i *uint32Value) String() string { return strconv.FormatUint(uint64(*i), 10) }
+
+// Uint32FromFlag return the uint32 value of a flag with the given name
+func Uint32FromFlag(fs *flag.FlagSet, name string) uint32 {
+	val := *fs.Lookup(name).Value.(*uint32Value)
+	return uint32(val)
+}

pkg/flags/int_test.go

@@ -0,0 +1,57 @@
+// Copyright 2018 The etcd Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package flags
+
+import (
+	"reflect"
+	"testing"
+)
+
+func TestInvalidUint32(t *testing.T) {
+	tests := []string{
+		// string
+		"invalid",
+		// negative number
+		"-1",
+		// float number
+		"0.1",
+		"-0.2",
+		// larger than math.MaxUint32
+		"4294967296",
+	}
+	for i, in := range tests {
+		var u uint32Value
+		if err := u.Set(in); err == nil {
+			t.Errorf(`#%d: unexpected nil error for in=%q`, i, in)
+		}
+	}
+}
+
+func TestUint32Value(t *testing.T) {
+	tests := []struct {
+		s   string
+		exp uint32
+	}{
+		{s: "0", exp: 0},
+		{s: "1", exp: 1},
+		{s: "", exp: 0},
+	}
+	for i := range tests {
+		ss := uint32(*NewUint32Value(tests[i].s))
+		if !reflect.DeepEqual(tests[i].exp, ss) {
+			t.Fatalf("#%d: expected %q, got %q", i, tests[i].exp, ss)
+		}
+	}
+}

server/config/config.go

@@ -129,6 +129,10 @@ type ServerConfig struct {
 	// MaxRequestBytes is the maximum request size to send over raft.
 	MaxRequestBytes uint
 
+	// MaxConcurrentStreams optionally specifies the number of concurrent
+	// streams that each client may have open at a time.
+	MaxConcurrentStreams uint32
+
 	WarningApplyDuration        time.Duration
 	WarningUnaryRequestDuration time.Duration
 

server/embed/config.go

@@ -17,6 +17,7 @@ package embed
 import (
 	"errors"
 	"fmt"
+	"math"
 	"net"
 	"net/http"
 	"net/url"
@@ -59,6 +60,7 @@ const (
 	DefaultWarningApplyDuration        = 100 * time.Millisecond
 	DefaultWarningUnaryRequestDuration = 300 * time.Millisecond
 	DefaultMaxRequestBytes             = 1.5 * 1024 * 1024
+	DefaultMaxConcurrentStreams        = math.MaxUint32
 	DefaultGRPCKeepAliveMinTime        = 5 * time.Second
 	DefaultGRPCKeepAliveInterval       = 2 * time.Hour
 	DefaultGRPCKeepAliveTimeout        = 20 * time.Second
@@ -205,6 +207,10 @@ type Config struct {
 	MaxTxnOps           uint   `json:"max-txn-ops"`
 	MaxRequestBytes     uint   `json:"max-request-bytes"`
 
+	// MaxConcurrentStreams optionally specifies the number of concurrent
+	// streams that each client may have open at a time.
+	MaxConcurrentStreams uint32 `json:"max-concurrent-streams"`
+
 	LPUrls, LCUrls []url.URL
 	APUrls, ACUrls []url.URL
 	ClientTLSInfo  transport.TLSInfo
@@ -311,7 +317,7 @@ type Config struct {
 	AuthToken  string `json:"auth-token"`
 	BcryptCost uint   `json:"bcrypt-cost"`
 
-	//The AuthTokenTTL in seconds of the simple token
+	// AuthTokenTTL in seconds of the simple token
 	AuthTokenTTL uint `json:"auth-token-ttl"`
 
 	ExperimentalInitialCorruptCheck bool          `json:"experimental-initial-corrupt-check"`
@@ -462,6 +468,7 @@ func NewConfig() *Config {
 
 		MaxTxnOps:                        DefaultMaxTxnOps,
 		MaxRequestBytes:                  DefaultMaxRequestBytes,
+		MaxConcurrentStreams:             DefaultMaxConcurrentStreams,
 		ExperimentalWarningApplyDuration: DefaultWarningApplyDuration,
 
 		ExperimentalWarningUnaryRequestDuration: DefaultWarningUnaryRequestDuration,

server/embed/etcd.go

@@ -191,6 +191,7 @@ func StartEtcd(inCfg *Config) (e *Etcd, err error) {
 		BackendBatchInterval:                     cfg.BackendBatchInterval,
 		MaxTxnOps:                                cfg.MaxTxnOps,
 		MaxRequestBytes:                          cfg.MaxRequestBytes,
+		MaxConcurrentStreams:                     cfg.MaxConcurrentStreams,
 		SocketOpts:                               cfg.SocketOpts,
 		StrictReconfigCheck:                      cfg.StrictReconfigCheck,
 		ClientCertAuthEnabled:                    cfg.ClientTLSInfo.ClientCertAuth,

server/embed/serve.go

@@ -44,6 +44,7 @@ import (
 	"github.com/soheilhy/cmux"
 	"github.com/tmc/grpc-websocket-proxy/wsproxy"
 	"go.uber.org/zap"
+	"golang.org/x/net/http2"
 	"golang.org/x/net/trace"
 	"google.golang.org/grpc"
 )
@@ -142,6 +143,9 @@ func (sctx *serveCtx) serve(
 			Handler:  createAccessController(sctx.lg, s, httpmux),
 			ErrorLog: logger, // do not log user error
 		}
+		if err := setMaxConcurrentStreams(srvhttp, s.Cfg.MaxConcurrentStreams); err != nil {
+			return err
+		}
 		httpl := m.Match(cmux.HTTP1())
 		go func() { errHandler(srvhttp.Serve(httpl)) }()
 
@@ -191,6 +195,9 @@ func (sctx *serveCtx) serve(
 			TLSConfig: tlscfg,
 			ErrorLog:  logger, // do not log user error
 		}
+		if err := setMaxConcurrentStreams(srv, s.Cfg.MaxConcurrentStreams); err != nil {
+			return err
+		}
 		go func() { errHandler(srv.Serve(tlsl)) }()
 
 		sctx.serversC <- &servers{secure: true, grpc: gs, http: srv}
@@ -204,6 +211,13 @@ func (sctx *serveCtx) serve(
 	return m.Serve()
 }
 
+// setMaxConcurrentStreams sets the maxConcurrentStreams for the http server
+func setMaxConcurrentStreams(srv *http.Server, maxConcurrentStreams uint32) error {
+	return http2.ConfigureServer(srv, &http2.Server{
+		MaxConcurrentStreams: maxConcurrentStreams,
+	})
+}
+
 // grpcHandlerFunc returns an http.Handler that delegates to grpcServer on incoming gRPC
 // connections or otherHandler otherwise. Given in gRPC docs.
 func grpcHandlerFunc(grpcServer *grpc.Server, otherHandler http.Handler) http.Handler {

server/etcdmain/config.go

@@ -142,6 +142,8 @@ func newConfig() *config {
 	fs.DurationVar(&rafthttp.ConnReadTimeout, "raft-read-timeout", rafthttp.DefaultConnReadTimeout, "Read timeout set on each rafthttp connection")
 	fs.DurationVar(&rafthttp.ConnWriteTimeout, "raft-write-timeout", rafthttp.DefaultConnWriteTimeout, "Write timeout set on each rafthttp connection")
 
+	fs.Var(flags.NewUint32Value(""), "max-concurrent-streams", "Maximum concurrent streams that each client may have open at a time.")
+
 	// clustering
 	fs.Var(
 		flags.NewUniqueURLsWithExceptions(embed.DefaultInitialAdvertisePeerURLs, ""),
@@ -380,6 +382,8 @@ func (cfg *config) configFromCmdLine() error {
 
 	cfg.ec.CipherSuites = flags.StringsFromFlag(cfg.cf.flagSet, "cipher-suites")
 
+	cfg.ec.MaxConcurrentStreams = flags.Uint32FromFlag(cfg.cf.flagSet, "max-concurrent-streams")
+
 	cfg.ec.LogOutputs = flags.UniqueStringsFromFlag(cfg.cf.flagSet, "log-outputs")
 
 	cfg.ec.ClusterState = cfg.cf.clusterState.String()

server/etcdmain/grpc_proxy.go

@@ -47,6 +47,7 @@ import (
 	"github.com/soheilhy/cmux"
 	"github.com/spf13/cobra"
 	"go.uber.org/zap"
+	"golang.org/x/net/http2"
 	"google.golang.org/grpc"
 	"google.golang.org/grpc/grpclog"
 	"google.golang.org/grpc/keepalive"
@@ -95,6 +96,8 @@ var (
 	grpcKeepAliveMinTime  time.Duration
 	grpcKeepAliveTimeout  time.Duration
 	grpcKeepAliveInterval time.Duration
+
+	maxConcurrentStreams uint32
 )
 
 const defaultGRPCMaxCallSendMsgSize = 1.5 * 1024 * 1024
@@ -159,6 +162,8 @@ func newGRPCProxyStartCommand() *cobra.Command {
 
 	cmd.Flags().BoolVar(&grpcProxyDebug, "debug", false, "Enable debug-level logging for grpc-proxy.")
 
+	cmd.Flags().Uint32Var(&maxConcurrentStreams, "max-concurrent-streams", math.MaxUint32, "Maximum concurrent streams that each client may have open at a time.")
+
 	return &cmd
 }
 
@@ -212,6 +217,12 @@ func startGRPCProxy(cmd *cobra.Command, args []string) {
 	httpClient := mustNewHTTPClient(lg)
 
 	srvhttp, httpl := mustHTTPListener(lg, m, tlsinfo, client, proxyClient)
+	if err := http2.ConfigureServer(srvhttp, &http2.Server{
+		MaxConcurrentStreams: maxConcurrentStreams,
+	}); err != nil {
+		panic(err)
+	}
+
 	errc := make(chan error, 3)
 	go func() { errc <- newGRPCProxyServer(lg, client).Serve(grpcl) }()
 	go func() { errc <- srvhttp.Serve(httpl) }()

server/etcdmain/help.go

@@ -81,6 +81,8 @@ Member:
     Maximum number of operations permitted in a transaction.
   --max-request-bytes '1572864'
     Maximum client request size in bytes the server will accept.
+  --max-concurrent-streams '0'
+    Maximum concurrent streams that each client may have open at a time.
   --grpc-keepalive-min-time '5s'
     Minimum duration interval that a client should wait before pinging server.
   --grpc-keepalive-interval '2h'

server/etcdserver/api/v3rpc/grpc.go

@@ -32,7 +32,6 @@ import (
 
 const (
 	grpcOverheadBytes = 512 * 1024
-	maxStreams        = math.MaxUint32
 	maxSendBytes      = math.MaxInt32
 )
 
@@ -68,7 +67,7 @@ func Server(s *etcdserver.EtcdServer, tls *tls.Config, interceptor grpc.UnarySer
 
 	opts = append(opts, grpc.MaxRecvMsgSize(int(s.Cfg.MaxRequestBytes+grpcOverheadBytes)))
 	opts = append(opts, grpc.MaxSendMsgSize(maxSendBytes))
-	opts = append(opts, grpc.MaxConcurrentStreams(maxStreams))
+	opts = append(opts, grpc.MaxConcurrentStreams(s.Cfg.MaxConcurrentStreams))
 
 	grpcServer := grpc.NewServer(append(opts, gopts...)...)