migrate to use memory-mlock flag

Signed-off-by: Jiayin Mao <jiayin.mao@datadoghq.com>

server/config/config.go

@@ -184,13 +184,13 @@ type ServerConfig struct {
 
 	DowngradeCheckTime time.Duration
 
-	// ExperimentalMemoryMlock enables mlocking of etcd owned memory pages.
+	// MemoryMlock enables mlocking of etcd owned memory pages.
 	// The setting improves etcd tail latency in environments were:
 	//   - memory pressure might lead to swapping pages to disk
 	//   - disk latency might be unstable
 	// Currently all etcd memory gets mlocked, but in future the flag can
 	// be refined to mlock in-use area of bbolt only.
-	ExperimentalMemoryMlock bool `json:"experimental-memory-mlock"`
+	MemoryMlock bool `json:"memory-mlock"`
 
 	// ExperimentalTxnModeWriteWithSharedBuffer enable write transaction to use
 	// a shared buffer in its readonly check operations.

server/embed/config.go

@@ -471,12 +471,16 @@ type Config struct {
 
 	ExperimentalDowngradeCheckTime time.Duration `json:"experimental-downgrade-check-time"`
 
-	// ExperimentalMemoryMlock enables mlocking of etcd owned memory pages.
+	// MemoryMlock enables mlocking of etcd owned memory pages.
 	// The setting improves etcd tail latency in environments were:
 	//   - memory pressure might lead to swapping pages to disk
 	//   - disk latency might be unstable
 	// Currently all etcd memory gets mlocked, but in future the flag can
 	// be refined to mlock in-use area of bbolt only.
+	MemoryMlock bool `json:"memory-mlock"`
+
+	// Deprecated in v3.6 and will be decommissioned in v3.7. Use MemoryMlock.
+	// TODO: Delete in v3.7
 	ExperimentalMemoryMlock bool `json:"experimental-memory-mlock"`
 
 	// ExperimentalTxnModeWriteWithSharedBuffer enables write transaction to use a shared buffer in its readonly check operations.
@@ -594,6 +598,7 @@ func NewConfig() *Config {
 		EnableGRPCGateway:     true,
 
 		ExperimentalDowngradeCheckTime:      DefaultDowngradeCheckTime,
+		MemoryMlock:                         false,
 		ExperimentalMemoryMlock:             false,
 		ExperimentalStopGRPCServiceOnDefrag: false,
 		ExperimentalMaxLearners:             membership.DefaultMaxLearners,
@@ -802,7 +807,9 @@ func (cfg *Config) AddFlags(fs *flag.FlagSet) {
 	fs.DurationVar(&cfg.ExperimentalWarningApplyDuration, "experimental-warning-apply-duration", cfg.ExperimentalWarningApplyDuration, "Time duration after which a warning is generated if request takes more time.")
 	fs.DurationVar(&cfg.WarningUnaryRequestDuration, "warning-unary-request-duration", cfg.WarningUnaryRequestDuration, "Time duration after which a warning is generated if a unary request takes more time.")
 	fs.DurationVar(&cfg.ExperimentalWarningUnaryRequestDuration, "experimental-warning-unary-request-duration", cfg.ExperimentalWarningUnaryRequestDuration, "Time duration after which a warning is generated if a unary request takes more time. It's deprecated, and will be decommissioned in v3.7. Use --warning-unary-request-duration instead.")
+	// TODO: delete in v3.7
 	fs.BoolVar(&cfg.ExperimentalMemoryMlock, "experimental-memory-mlock", cfg.ExperimentalMemoryMlock, "Enable to enforce etcd pages (in particular bbolt) to stay in RAM.")
+	fs.BoolVar(&cfg.MemoryMlock, "memory-mlock", cfg.MemoryMlock, "Enable to enforce etcd pages (in particular bbolt) to stay in RAM.")
 	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.BoolVar(&cfg.ExperimentalStopGRPCServiceOnDefrag, "experimental-stop-grpc-service-on-defrag", cfg.ExperimentalStopGRPCServiceOnDefrag, "Enable etcd gRPC service to stop serving client requests on defragmentation.")
 	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.")

server/embed/etcd.go

@@ -221,7 +221,7 @@ func StartEtcd(inCfg *Config) (e *Etcd, err error) {
 		DowngradeCheckTime:                   cfg.ExperimentalDowngradeCheckTime,
 		WarningApplyDuration:                 cfg.ExperimentalWarningApplyDuration,
 		WarningUnaryRequestDuration:          cfg.WarningUnaryRequestDuration,
-		ExperimentalMemoryMlock:              cfg.ExperimentalMemoryMlock,
+		MemoryMlock:                          cfg.MemoryMlock,
 		ExperimentalBootstrapDefragThresholdMegabytes: cfg.ExperimentalBootstrapDefragThresholdMegabytes,
 		ExperimentalMaxLearners:                       cfg.ExperimentalMaxLearners,
 		V2Deprecation:                                 cfg.V2DeprecationEffective(),

server/etcdmain/config.go

@@ -67,6 +67,7 @@ var (
 		"experimental-txn-mode-write-with-shared-buffer": "--experimental-txn-mode-write-with-shared-buffer is deprecated in v3.6 and will be decommissioned in v3.7. Use '--feature-gates=TxnModeWriteWithSharedBuffer=true' instead.",
 		"experimental-corrupt-check-time":                "--experimental-corrupt-check-time is deprecated in v3.6 and will be decommissioned in v3.7. Use '--corrupt-check-time' instead.",
 		"experimental-compaction-batch-limit":            "--experimental-compaction-batch-limit is deprecated in v3.6 and will be decommissioned in v3.7. Use '--compaction-batch-limit' instead.",
+		"experimental-memory-mlock":                      "--experimental-memory-mlock is deprecated in v3.6 and will be decommissioned in v3.7. Use '--memory-mlock' instead.",
 	}
 )
 
@@ -184,6 +185,10 @@ func (cfg *config) parse(arguments []string) error {
 		cfg.ec.CompactionBatchLimit = cfg.ec.ExperimentalCompactionBatchLimit
 	}
 
+	if cfg.ec.FlagsExplicitlySet["experimental-memory-mlock"] {
+		cfg.ec.MemoryMlock = cfg.ec.ExperimentalMemoryMlock
+	}
+
 	// `V2Deprecation` (--v2-deprecation) is deprecated and scheduled for removal in v3.8. The default value is enforced, ignoring user input.
 	cfg.ec.V2Deprecation = cconfig.V2DeprDefault
 

server/etcdmain/config_test.go

@@ -701,6 +701,65 @@ func TestCompactionBatchLimitFlagMigration(t *testing.T) {
 	}
 }
 
+// TestMemoryMlockFlagMigration tests the migration from
+// --experimental-memory-mlock to --memory-mlock
+// TODO: delete in v3.7
+func TestMemoryMlockFlagMigration(t *testing.T) {
+	testCases := []struct {
+		name                    string
+		memoryMlock             bool
+		experimentalMemoryMlock bool
+		expectedMemoryMlock     bool
+	}{
+		{
+			name:                "default",
+			expectedMemoryMlock: false,
+		},
+		{
+			name:                    "can set experimental flag",
+			experimentalMemoryMlock: true,
+			expectedMemoryMlock:     true,
+		},
+		{
+			name:                "can set non experimental flag",
+			memoryMlock:         true,
+			expectedMemoryMlock: true,
+		},
+	}
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
+			cmdLineArgs := []string{}
+			yc := struct {
+				MemoryMlock             bool `json:"memory-mlock,omitempty"`
+				ExperimentalMemoryMlock bool `json:"experimental-memory-mlock,omitempty"`
+			}{}
+
+			if tc.memoryMlock {
+				cmdLineArgs = append(cmdLineArgs, "--memory-mlock")
+				yc.MemoryMlock = tc.memoryMlock
+			}
+
+			if tc.experimentalMemoryMlock {
+				cmdLineArgs = append(cmdLineArgs, "--experimental-memory-mlock")
+				yc.ExperimentalMemoryMlock = tc.experimentalMemoryMlock
+			}
+
+			cfgFromCmdLine, errFromCmdLine, cfgFromFile, errFromFile := generateCfgsFromFileAndCmdLine(t, yc, cmdLineArgs)
+
+			if errFromCmdLine != nil || errFromFile != nil {
+				t.Fatal("error parsing config")
+			}
+
+			if cfgFromCmdLine.ec.MemoryMlock != tc.expectedMemoryMlock {
+				t.Errorf("expected MemoryMlock=%v, got %v", tc.expectedMemoryMlock, cfgFromCmdLine.ec.MemoryMlock)
+			}
+			if cfgFromFile.ec.MemoryMlock != tc.expectedMemoryMlock {
+				t.Errorf("expected MemoryMlock=%v, got %v", tc.expectedMemoryMlock, cfgFromFile.ec.MemoryMlock)
+			}
+		})
+	}
+}
+
 // TODO delete in v3.7
 func generateCfgsFromFileAndCmdLine(t *testing.T, yc any, cmdLineArgs []string) (*config, error, *config, error) {
 	b, err := yaml.Marshal(&yc)

server/etcdmain/help.go

@@ -75,6 +75,8 @@ Member:
     Maximum number of snapshot files to retain (0 is unlimited). Deprecated in v3.6 and will be decommissioned in v3.7.
   --max-wals '` + strconv.Itoa(embed.DefaultMaxWALs) + `'
     Maximum number of wal files to retain (0 is unlimited).
+  --memory-mlock
+    Enable to enforce etcd pages (in particular bbolt) to stay in RAM.
   --quota-backend-bytes '0'
     Raise alarms when backend size exceeds the given quota (0 defaults to low space quota).
   --backend-bbolt-freelist-type 'map'

server/storage/backend.go

@@ -50,7 +50,7 @@ func newBackend(cfg config.ServerConfig, hooks backend.Hooks) backend.Backend {
 		// permit 10% excess over quota for disarm
 		bcfg.MmapSize = uint64(cfg.QuotaBackendBytes + cfg.QuotaBackendBytes/10)
 	}
-	bcfg.Mlock = cfg.ExperimentalMemoryMlock
+	bcfg.Mlock = cfg.MemoryMlock
 	bcfg.Hooks = hooks
 	return backend.New(bcfg)
 }