This is an automated cherry-pick of pingcap#3474

Signed-off-by: ti-chi-bot <ti-community-prow-bot@tidb.io>

dm/dm/master/scheduler/scheduler.go

@@ -1780,6 +1780,16 @@ func (s *Scheduler) handleWorkerOnline(ev ha.WorkerEvent, toLock bool) error {
 
 	// 3. change the stage (from Offline) to Free or Relay.
 	lastRelaySource := w.RelaySourceID()
+	if lastRelaySource == "" {
+		// when worker is removed (for example lost keepalive when master scheduler boots up), w.RelaySourceID() is
+		// of course nothing, so we find the relay source from a better place
+		for source, workerM := range s.relayWorkers {
+			if _, ok2 := workerM[w.BaseInfo().Name]; ok2 {
+				lastRelaySource = source
+				break
+			}
+		}
+	}
 	w.ToFree()
 	// TODO: rename ToFree to Online and move below logic inside it
 	if lastRelaySource != "" {

dm/tests/new_relay/conf/source2.yaml

@@ -0,0 +1,14 @@
+source-id: mysql-replica-02
+server-id: 123456
+flavor: 'mysql'
+enable-gtid: true
+relay-binlog-name: ''
+relay-binlog-gtid: ''
+enable-relay: false
+from:
+  host: 127.0.0.1
+  user: root
+  password: /Q7B9DizNLLTTfiZHv9WoEAKamfpIUs=
+  port: 3307
+checker:
+  check-enable: false

dm/tests/new_relay/run.sh

@@ -43,6 +43,125 @@ function test_cant_dail_upstream() {
 	cleanup_data $TEST_NAME
 }
 
+<<<<<<< HEAD
+=======
+function test_cant_dail_downstream() {
+	cleanup_data $TEST_NAME
+	cleanup_process
+
+	run_dm_master $WORK_DIR/master $MASTER_PORT $cur/conf/dm-master.toml
+	check_rpc_alive $cur/../bin/check_master_online 127.0.0.1:$MASTER_PORT
+	run_dm_worker $WORK_DIR/worker1 $WORKER1_PORT $cur/conf/dm-worker1.toml
+	check_rpc_alive $cur/../bin/check_worker_online 127.0.0.1:$WORKER1_PORT
+
+	cp $cur/conf/source1.yaml $WORK_DIR/source1.yaml
+	dmctl_operate_source create $WORK_DIR/source1.yaml $SOURCE_ID1
+
+	run_dm_ctl_with_retry $WORK_DIR "127.0.0.1:$MASTER_PORT" \
+		"start-relay -s $SOURCE_ID1 worker1" \
+		"\"result\": true" 1
+	dmctl_start_task_standalone $cur/conf/dm-task.yaml "--remove-meta"
+
+	kill_dm_worker
+	# kill tidb
+	pkill -hup tidb-server 2>/dev/null || true
+	wait_process_exit tidb-server
+
+	run_dm_worker $WORK_DIR/worker1 $WORKER1_PORT $cur/conf/dm-worker1.toml
+	check_rpc_alive $cur/../bin/check_worker_online 127.0.0.1:$WORKER1_PORT
+
+	# make sure DM-worker doesn't exit
+	sleep 2
+	run_dm_ctl_with_retry $WORK_DIR "127.0.0.1:$MASTER_PORT" \
+		"query-status -s $SOURCE_ID1" \
+		"\"relayCatchUpMaster\": true" 1 \
+		"dial tcp 127.0.0.1:4000: connect: connection refused" 1
+
+	# restart tidb
+	run_tidb_server 4000 $TIDB_PASSWORD
+	sleep 2
+
+	cleanup_process
+	cleanup_data $TEST_NAME
+}
+
+function test_restart_relay_status() {
+	cleanup_data $TEST_NAME
+	cleanup_process
+
+	run_dm_master $WORK_DIR/master $MASTER_PORT $cur/conf/dm-master.toml
+	check_rpc_alive $cur/../bin/check_master_online 127.0.0.1:$MASTER_PORT
+	run_dm_worker $WORK_DIR/worker1 $WORKER1_PORT $cur/conf/dm-worker1.toml
+	check_rpc_alive $cur/../bin/check_worker_online 127.0.0.1:$WORKER1_PORT
+
+	dmctl_operate_source create $cur/conf/source1.yaml $SOURCE_ID1
+
+	run_dm_ctl_with_retry $WORK_DIR "127.0.0.1:$MASTER_PORT" \
+		"start-relay -s $SOURCE_ID1 worker1"
+	run_dm_ctl_with_retry $WORK_DIR "127.0.0.1:$MASTER_PORT" \
+		"query-status -s $SOURCE_ID1" \
+		"\"result\": true" 2 \
+		"\"worker\": \"worker1\"" 1
+
+	run_dm_worker $WORK_DIR/worker2 $WORKER2_PORT $cur/conf/dm-worker2.toml
+	check_rpc_alive $cur/../bin/check_worker_online 127.0.0.1:$WORKER2_PORT
+
+	dmctl_operate_source create $cur/conf/source2.yaml $SOURCE_ID2
+
+	run_dm_ctl_with_retry $WORK_DIR "127.0.0.1:$MASTER_PORT" \
+		"start-relay -s $SOURCE_ID2 worker2"
+	run_dm_ctl_with_retry $WORK_DIR "127.0.0.1:$MASTER_PORT" \
+		"query-status -s $SOURCE_ID2" \
+		"\"result\": true" 2 \
+		"\"worker\": \"worker2\"" 1
+
+	run_dm_worker $WORK_DIR/worker3 $WORKER3_PORT $cur/conf/dm-worker3.toml
+	check_rpc_alive $cur/../bin/check_worker_online 127.0.0.1:$WORKER3_PORT
+
+	run_dm_ctl_with_retry $WORK_DIR "127.0.0.1:$MASTER_PORT" \
+		"start-relay -s $SOURCE_ID2 worker3"
+	run_dm_ctl_with_retry $WORK_DIR "127.0.0.1:$MASTER_PORT" \
+		"query-status -s $SOURCE_ID2" \
+		"\"result\": true" 3 \
+		"\"worker\": \"worker2\"" 1 \
+		"\"worker\": \"worker3\"" 1
+
+	run_dm_ctl $WORK_DIR "127.0.0.1:$MASTER_PORT" \
+		"list-member -n worker3" \
+		"relay" 1
+
+	kill_dm_worker
+	kill_dm_master
+
+	run_dm_master $WORK_DIR/master $MASTER_PORT $cur/conf/dm-master.toml
+	check_rpc_alive $cur/../bin/check_master_online 127.0.0.1:$MASTER_PORT
+
+	run_dm_worker $WORK_DIR/worker1 $WORKER1_PORT $cur/conf/dm-worker1.toml
+	run_dm_worker $WORK_DIR/worker3 $WORKER3_PORT $cur/conf/dm-worker3.toml
+	check_rpc_alive $cur/../bin/check_worker_online 127.0.0.1:$WORKER1_PORT
+	check_rpc_alive $cur/../bin/check_worker_online 127.0.0.1:$WORKER3_PORT
+
+	run_dm_worker $WORK_DIR/worker2 $WORKER2_PORT $cur/conf/dm-worker2.toml
+	check_rpc_alive $cur/../bin/check_worker_online 127.0.0.1:$WORKER2_PORT
+
+	run_dm_ctl_with_retry $WORK_DIR "127.0.0.1:$MASTER_PORT" \
+		"query-status -s $SOURCE_ID1" \
+		"\"result\": true" 2 \
+		"\"worker\": \"worker1\"" 1
+
+	run_dm_ctl_with_retry $WORK_DIR "127.0.0.1:$MASTER_PORT" \
+		"query-status -s $SOURCE_ID2" \
+		"\"result\": true" 3 \
+		"\"worker\": \"worker2\"" 1 \
+		"\"worker\": \"worker3\"" 1
+
+	run_dm_ctl $WORK_DIR "127.0.0.1:$MASTER_PORT" \
+		"list-member --worker" \
+		"relay" 1 \
+		"bound" 2
+}
+
+>>>>>>> a839044e8 (dm/scheduler: fix inconsistent of relay status (#3474))
 function test_kill_dump_connection() {
 	cleanup_data $TEST_NAME
 	cleanup_process
@@ -68,7 +187,7 @@ function test_kill_dump_connection() {
 		"\"worker\": \"worker1\"" 1
 	run_sql_source1 "show processlist"
 
-	# kill dumop connection to test wheather relay will auto reconnect db
+	# kill dump connection to test whether relay will auto reconnect db
 	dump_conn_id=$(cat $TEST_DIR/sql_res.$TEST_NAME.txt | grep Binlog -B 4 | grep Id | cut -d : -f2)
 	run_sql_source1 "kill ${dump_conn_id}"
 
@@ -83,6 +202,11 @@ function test_kill_dump_connection() {
 }
 
 function run() {
+<<<<<<< HEAD
+=======
+	test_restart_relay_status
+	test_cant_dail_downstream
+>>>>>>> a839044e8 (dm/scheduler: fix inconsistent of relay status (#3474))
 	test_cant_dail_upstream
 
 	export GO_FAILPOINTS="github.com/pingcap/ticdc/dm/relay/ReportRelayLogSpaceInBackground=return(1)"