Fix switchover when many connection appear

README.md

@@ -116,6 +116,7 @@ replication_repair_max_attempts: 3
 
 external_replication_type: off
 show_only_gtid_diff: False
+force_switchover: False
 ```
 
 ### Usage

internal/app/app.go

@@ -1208,6 +1208,21 @@ func (app *App) performSwitchover(clusterState map[string]*NodeState, activeNode
 		}
 		node := app.cluster.Get(host)
 		// in case node is a master
+
+		if app.config.ForceSwitchover {
+			err := node.SetOffline()
+			if err != nil {
+				app.logger.Infof("switchover: failed to set node %s offline: %v", host, err)
+				return fmt.Errorf("failed to set node %s read-only: %v", host, err)
+			}
+
+			err = node.SemiSyncDisable()
+			if err != nil {
+				app.logger.Infof("switchover: failed to disable semi-sync on node %s: %v", host, err)
+				return fmt.Errorf("failed to set node %s read-only: %v", host, err)
+			}
+		}
+
 		err := node.SetReadOnly(true)
 		if err != nil || app.emulateError("freeze_ro") {
 			app.logger.Infof("switchover: failed to set node %s read-only, trying kill bad queries: %v", host, err)

internal/config/config.go

@@ -97,6 +97,7 @@ type Config struct {
 	ReplMonErrorWaitInterval                time.Duration                `config:"repl_mon_error_wait_interval" yaml:"repl_mon_error_wait_interval"`
 	ReplMonSlaveWaitInterval                time.Duration                `config:"repl_mon_slave_wait_interval" yaml:"repl_mon_slave_wait_interval"`
 	ShowOnlyGTIDDiff                        bool                         `config:"show_only_gtid_diff" yaml:"show_only_gtid_diff"`
+	ForceSwitchover                         bool                         `config:"force_switchover" yaml:"force_switchover"`
 }
 
 // DefaultConfig returns default configuration for MySync
@@ -182,6 +183,7 @@ func DefaultConfig() (Config, error) {
 		ReplMonErrorWaitInterval:                10 * time.Second,
 		ReplMonSlaveWaitInterval:                10 * time.Second,
 		ShowOnlyGTIDDiff:                        false,
+		ForceSwitchover:                         false,
 	}
 	return config, nil
 }

tests/images/mysql/mysync.yaml

@@ -62,3 +62,4 @@ replication_channel: ''
 external_replication_type: 'external'
 show_only_gtid_diff: false
 repl_mon: ${REPL_MON:-false}
+force_switchover: false