Revert "etcd server shouldn't wait for the ready notification infinitely on startup"

CHANGELOG/CHANGELOG-3.6.md

@@ -65,7 +65,6 @@ See [code changes](https://github.com/etcd-io/etcd/compare/v3.5.0...v3.6.0).
 - Add [`etcd --experimental-max-learners`](https://github.com/etcd-io/etcd/pull/13377) flag to allow configuration of learner max membership.
 - Add [`etcd --experimental-enable-lease-checkpoint-persist`](https://github.com/etcd-io/etcd/pull/13508) flag to handle upgrade from v3.5.2 clusters with this feature enabled.
 - Add [`etcdctl make-mirror --rev`](https://github.com/etcd-io/etcd/pull/13519) flag to support incremental mirror.
-- Add [`etcd --experimental-wait-cluster-ready-timeout`](https://github.com/etcd-io/etcd/pull/13525) flag to wait for cluster to be ready before serving client requests.
 - Add [v3 discovery](https://github.com/etcd-io/etcd/pull/13635) to bootstrap a new etcd cluster.
 - Add [field `storage`](https://github.com/etcd-io/etcd/pull/13772) into the response body of endpoint `/version`.
 - Add [`etcd --max-concurrent-streams`](https://github.com/etcd-io/etcd/pull/14169) flag to configure the max concurrent streams each client can open at a time, and defaults to math.MaxUint32.

server/config/config.go

@@ -83,10 +83,6 @@ type ServerConfig struct {
 	TickMs        uint
 	ElectionTicks int
 
-	// WaitClusterReadyTimeout is the maximum time to wait for the
-	// cluster to be ready on startup before serving client requests.
-	WaitClusterReadyTimeout time.Duration
-
 	// InitialElectionTickAdvance is true, then local member fast-forwards
 	// election ticks to speed up "initial" leader election trigger. This
 	// benefits the case of larger election ticks. For instance, cross

server/embed/config.go

@@ -68,7 +68,6 @@ const (
 	DefaultGRPCKeepAliveInterval       = 2 * time.Hour
 	DefaultGRPCKeepAliveTimeout        = 20 * time.Second
 	DefaultDowngradeCheckTime          = 5 * time.Second
-	DefaultWaitClusterReadyTimeout     = 5 * time.Second
 	DefaultAutoCompactionMode          = "periodic"
 
 	DefaultDiscoveryDialTimeout      = 2 * time.Second
@@ -242,10 +241,9 @@ type Config struct {
 	Durl         string                      `json:"discovery"`
 	DiscoveryCfg v3discovery.DiscoveryConfig `json:"discovery-config"`
 
-	InitialCluster                      string        `json:"initial-cluster"`
-	InitialClusterToken                 string        `json:"initial-cluster-token"`
-	StrictReconfigCheck                 bool          `json:"strict-reconfig-check"`
-	ExperimentalWaitClusterReadyTimeout time.Duration `json:"wait-cluster-ready-timeout"`
+	InitialCluster      string `json:"initial-cluster"`
+	InitialClusterToken string `json:"initial-cluster-token"`
+	StrictReconfigCheck bool   `json:"strict-reconfig-check"`
 
 	// AutoCompactionMode is either 'periodic' or 'revision'.
 	AutoCompactionMode string `json:"auto-compaction-mode"`
@@ -502,9 +500,8 @@ func NewConfig() *Config {
 		AdvertisePeerUrls:   []url.URL{*apurl},
 		AdvertiseClientUrls: []url.URL{*acurl},
 
-		ClusterState:                        ClusterStateFlagNew,
-		InitialClusterToken:                 "etcd-cluster",
-		ExperimentalWaitClusterReadyTimeout: DefaultWaitClusterReadyTimeout,
+		ClusterState:        ClusterStateFlagNew,
+		InitialClusterToken: "etcd-cluster",
 
 		StrictReconfigCheck: DefaultStrictReconfigCheck,
 		Metrics:             "basic",
@@ -728,7 +725,6 @@ func (cfg *Config) AddFlags(fs *flag.FlagSet) {
 	fs.BoolVar(&cfg.ExperimentalTxnModeWriteWithSharedBuffer, "experimental-txn-mode-write-with-shared-buffer", true, "Enable the write transaction to use a shared buffer in its readonly check operations.")
 	fs.UintVar(&cfg.ExperimentalBootstrapDefragThresholdMegabytes, "experimental-bootstrap-defrag-threshold-megabytes", 0, "Enable the defrag during etcd server bootstrap on condition that it will free at least the provided threshold of disk space. Needs to be set to non-zero value to take effect.")
 	fs.IntVar(&cfg.ExperimentalMaxLearners, "experimental-max-learners", membership.DefaultMaxLearners, "Sets the maximum number of learners that can be available in the cluster membership.")
-	fs.DurationVar(&cfg.ExperimentalWaitClusterReadyTimeout, "experimental-wait-cluster-ready-timeout", cfg.ExperimentalWaitClusterReadyTimeout, "Maximum duration to wait for the cluster to be ready.")
 	fs.Uint64Var(&cfg.SnapshotCatchUpEntries, "experimental-snapshot-catchup-entries", cfg.SnapshotCatchUpEntries, "Number of entries for a slow follower to catch up after compacting the raft storage entries.")
 
 	// unsafe

server/embed/etcd.go

@@ -185,7 +185,6 @@ func StartEtcd(inCfg *Config) (e *Etcd, err error) {
 		PeerTLSInfo:                              cfg.PeerTLSInfo,
 		TickMs:                                   cfg.TickMs,
 		ElectionTicks:                            cfg.ElectionTicks(),
-		WaitClusterReadyTimeout:                  cfg.ExperimentalWaitClusterReadyTimeout,
 		InitialElectionTickAdvance:               cfg.InitialElectionTickAdvance,
 		AutoCompactionRetention:                  autoCompactionRetention,
 		AutoCompactionMode:                       cfg.AutoCompactionMode,
@@ -328,7 +327,6 @@ func print(lg *zap.Logger, ec Config, sc config.ServerConfig, memberInitialized
 		zap.Bool("force-new-cluster", sc.ForceNewCluster),
 		zap.String("heartbeat-interval", fmt.Sprintf("%v", time.Duration(sc.TickMs)*time.Millisecond)),
 		zap.String("election-timeout", fmt.Sprintf("%v", time.Duration(sc.ElectionTicks*int(sc.TickMs))*time.Millisecond)),
-		zap.String("wait-cluster-ready-timeout", sc.WaitClusterReadyTimeout.String()),
 		zap.Bool("initial-election-tick-advance", sc.InitialElectionTickAdvance),
 		zap.Uint64("snapshot-count", sc.SnapshotCount),
 		zap.Uint("max-wals", sc.MaxWALFiles),

server/embed/serve.go

@@ -22,7 +22,6 @@ import (
 	"net"
 	"net/http"
 	"strings"
-	"time"
 
 	gw "github.com/grpc-ecosystem/grpc-gateway/v2/runtime"
 	"github.com/soheilhy/cmux"
@@ -100,15 +99,7 @@ func (sctx *serveCtx) serve(
 	splitHttp bool,
 	gopts ...grpc.ServerOption) (err error) {
 	logger := defaultLog.New(io.Discard, "etcdhttp", 0)
-
-	// When the quorum isn't satisfied, then etcd server will be blocked
-	// on <-s.ReadyNotify(). Set a timeout here so that the etcd server
-	// can continue to serve serializable read request.
-	select {
-	case <-time.After(s.Cfg.WaitClusterReadyTimeout):
-		sctx.lg.Warn("timed out waiting for the ready notification")
-	case <-s.ReadyNotify():
-	}
+	<-s.ReadyNotify()
 
 	sctx.lg.Info("ready to serve client requests")
 

server/etcdmain/etcd.go

@@ -19,7 +19,6 @@ import (
 	"os"
 	"runtime"
 	"strings"
-	"time"
 
 	"go.uber.org/zap"
 	"google.golang.org/grpc"
@@ -211,8 +210,6 @@ func startEtcd(cfg *embed.Config) (<-chan struct{}, <-chan error, error) {
 	select {
 	case <-e.Server.ReadyNotify(): // wait for e.Server to join the cluster
 	case <-e.Server.StopNotify(): // publish aborted from 'ErrStopped'
-	case <-time.After(cfg.ExperimentalWaitClusterReadyTimeout):
-		e.GetLogger().Warn("startEtcd: timed out waiting for the ready notification")
 	}
 	return e.Server.StopNotify(), e.Err(), nil
 }

server/etcdmain/help.go

@@ -293,8 +293,6 @@ Experimental feature:
     Set time duration after which a warning is generated if a unary request takes more than this duration. It's deprecated, and will be decommissioned in v3.7. Use --warning-unary-request-duration instead.
   --experimental-max-learners '1'
     Set the max number of learner members allowed in the cluster membership.
-  --experimental-wait-cluster-ready-timeout '5s'
-    Set the maximum time duration to wait for the cluster to be ready.
   --experimental-snapshot-catch-up-entries '5000'
     Number of entries for a slow follower to catch up after compacting the raft storage entries.
   --experimental-compaction-sleep-interval

tests/e2e/corrupt_test.go

@@ -12,11 +12,14 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
+//go:build !cluster_proxy
+
 package e2e
 
 import (
 	"context"
 	"fmt"
+	"sync"
 	"testing"
 	"time"
 
@@ -155,22 +158,30 @@ func TestInPlaceRecovery(t *testing.T) {
 	assert.NoError(t, err)
 
 	// Rolling recovery of the servers.
+	wg := sync.WaitGroup{}
 	t.Log("rolling updating servers in place...")
-	for i, newProc := range epcNew.Procs {
+	for i := range epcNew.Procs {
 		oldProc := epcOld.Procs[i]
 		err = oldProc.Close()
 		if err != nil {
 			t.Fatalf("could not stop etcd process (%v)", err)
 		}
 		t.Logf("old cluster server %d: %s stopped.", i, oldProc.Config().Name)
-		err = newProc.Start(ctx)
-		if err != nil {
-			t.Fatalf("could not start etcd process (%v)", err)
-		}
-		t.Logf("new cluster server %d: %s started in-place with blank db.", i, newProc.Config().Name)
+		wg.Add(1)
+		// Start servers in background to avoid blocking on server start.
+		// EtcdProcess.Start waits until etcd becomes healthy, which will not happen here until we restart at least 2 members.
+		go func(proc e2e.EtcdProcess) {
+			defer wg.Done()
+			err = proc.Start(ctx)
+			if err != nil {
+				t.Errorf("could not start etcd process (%v)", err)
+			}
+			t.Logf("new cluster server: %s started in-place with blank db.", proc.Config().Name)
+		}(epcNew.Procs[i])
 		t.Log("sleeping 5 sec to let nodes do periodical check...")
 		time.Sleep(5 * time.Second)
 	}
+	wg.Wait()
 	t.Log("new cluster started.")
 
 	alarmResponse, err := newCc.AlarmList(ctx)

tests/e2e/ctl_v3_member_test.go

@@ -69,7 +69,6 @@ func TestCtlV3ConsistentMemberList(t *testing.T) {
 
 	epc, err := e2e.NewEtcdProcessCluster(ctx, t,
 		e2e.WithClusterSize(1),
-		e2e.WithWaitClusterReadyTimeout(1*time.Nanosecond),
 		e2e.WithEnvVars(map[string]string{"GOFAIL_FAILPOINTS": `beforeApplyOneConfChange=sleep("2s")`}),
 	)
 	require.NoError(t, err, "failed to start etcd cluster: %v", err)

tests/framework/e2e/cluster.go

@@ -354,10 +354,6 @@ func WithWatchProcessNotifyInterval(interval time.Duration) EPClusterOption {
 	return func(c *EtcdProcessClusterConfig) { c.ServerConfig.ExperimentalWatchProgressNotifyInterval = interval }
 }
 
-func WithWaitClusterReadyTimeout(readyTimeout time.Duration) EPClusterOption {
-	return func(c *EtcdProcessClusterConfig) { c.ServerConfig.ExperimentalWaitClusterReadyTimeout = readyTimeout }
-}
-
 func WithEnvVars(ev map[string]string) EPClusterOption {
 	return func(c *EtcdProcessClusterConfig) { c.EnvVars = ev }
 }
@@ -601,9 +597,6 @@ func (cfg *EtcdProcessClusterConfig) EtcdServerProcessConfig(tb testing.TB, i in
 	if cfg.ServerConfig.ExperimentalWatchProgressNotifyInterval != 0 {
 		args = append(args, "--experimental-watch-progress-notify-interval", cfg.ServerConfig.ExperimentalWatchProgressNotifyInterval.String())
 	}
-	if cfg.ServerConfig.ExperimentalWaitClusterReadyTimeout != 0 {
-		args = append(args, "--experimental-wait-cluster-ready-timeout", cfg.ServerConfig.ExperimentalWaitClusterReadyTimeout.String())
-	}
 	if cfg.ServerConfig.SnapshotCatchUpEntries != etcdserver.DefaultSnapshotCatchUpEntries {
 		if cfg.Version == CurrentVersion || (cfg.Version == MinorityLastVersion && i <= cfg.ClusterSize/2) || (cfg.Version == QuorumLastVersion && i > cfg.ClusterSize/2) {
 			args = append(args, "--experimental-snapshot-catchup-entries", fmt.Sprintf("%d", cfg.ServerConfig.SnapshotCatchUpEntries))