This is an automated cherry-pick of tikv#4875

close tikv#4769

Signed-off-by: ti-chi-bot <[email protected]>

server/cluster/cluster.go

@@ -593,6 +593,11 @@ func (c *RaftCluster) HandleStoreHeartbeat(stats *pdpb.StoreStats) error {
 	return nil
 }
 
+// IsPrepared return true if the prepare checker is ready.
+func (c *RaftCluster) IsPrepared() bool {
+	return c.coordinator.prepareChecker.isPrepared()
+}
+
 var regionGuide = core.GenerateRegionGuideFunc(true)
 
 // processRegionHeartbeat updates the region information.
@@ -663,8 +668,13 @@ func (c *RaftCluster) processRegionHeartbeat(region *core.RegionInfo) error {
 		regionEventCounter.WithLabelValues("update_cache").Inc()
 	}
 
+<<<<<<< HEAD
 	if isNew {
 		c.prepareChecker.collect(region)
+=======
+	if !c.IsPrepared() && isNew {
+		c.coordinator.prepareChecker.collect(region)
+>>>>>>> 429b49283 (*: fix scheduling can not immediately start after transfer leader (#4875))
 	}
 
 	if c.regionStats != nil {
@@ -718,13 +728,16 @@ func (c *RaftCluster) updateStoreStatusLocked(id uint64) {
 	c.core.UpdateStoreStatus(id, leaderCount, regionCount, pendingPeerCount, leaderRegionSize, regionSize)
 }
 
+<<<<<<< HEAD
 //nolint:unused
 func (c *RaftCluster) getClusterID() uint64 {
 	c.RLock()
 	defer c.RUnlock()
 	return c.meta.GetId()
 }
 
+=======
+>>>>>>> 429b49283 (*: fix scheduling can not immediately start after transfer leader (#4875))
 func (c *RaftCluster) putMetaLocked(meta *metapb.Cluster) error {
 	if c.storage != nil {
 		if err := c.storage.SaveMeta(meta); err != nil {

server/cluster/coordinator.go

@@ -279,6 +279,9 @@ func (c *coordinator) drivePushOperator() {
 
 func (c *coordinator) run() {
 	ticker := time.NewTicker(runSchedulerCheckInterval)
+	failpoint.Inject("changeCoordinatorTicker", func() {
+		ticker = time.NewTicker(100 * time.Millisecond)
+	})
 	defer ticker.Stop()
 	log.Info("coordinator starts to collect cluster information")
 	for {

server/cluster/coordinator_test.go

@@ -191,7 +191,11 @@ func (s *testCoordinatorSuite) TestBasic(c *C) {
 func (s *testCoordinatorSuite) TestDispatch(c *C) {
 	tc, co, cleanup := prepare(nil, func(tc *testCluster) { tc.prepareChecker.isPrepared = true }, nil, c)
 	defer cleanup()
+<<<<<<< HEAD
 
+=======
+	co.prepareChecker.prepared = true
+>>>>>>> 429b49283 (*: fix scheduling can not immediately start after transfer leader (#4875))
 	// Transfer peer from store 4 to store 1.
 	c.Assert(tc.addRegionStore(4, 40), IsNil)
 	c.Assert(tc.addRegionStore(3, 30), IsNil)
@@ -284,7 +288,7 @@ func prepare(setCfg func(*config.ScheduleConfig), setTc func(*testCluster), run
 		setCfg(cfg)
 	}
 	tc := newTestCluster(ctx, opt)
-	hbStreams := hbstream.NewTestHeartbeatStreams(ctx, tc.getClusterID(), tc, true /* need to run */)
+	hbStreams := hbstream.NewTestHeartbeatStreams(ctx, tc.meta.GetId(), tc, true /* need to run */)
 	if setTc != nil {
 		setTc(tc)
 	}

server/cluster/prepare_checker.go

@@ -0,0 +1,81 @@
+// Copyright 2022 TiKV Project 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 cluster
+
+import (
+	"time"
+
+	"github.com/tikv/pd/pkg/syncutil"
+	"github.com/tikv/pd/server/core"
+)
+
+type prepareChecker struct {
+	syncutil.RWMutex
+	reactiveRegions map[uint64]int
+	start           time.Time
+	sum             int
+	prepared        bool
+}
+
+func newPrepareChecker() *prepareChecker {
+	return &prepareChecker{
+		start:           time.Now(),
+		reactiveRegions: make(map[uint64]int),
+	}
+}
+
+// Before starting up the scheduler, we need to take the proportion of the regions on each store into consideration.
+func (checker *prepareChecker) check(c *core.BasicCluster) bool {
+	checker.RLock()
+	defer checker.RUnlock()
+	if checker.prepared {
+		return true
+	}
+	if time.Since(checker.start) > collectTimeout {
+		checker.prepared = true
+		return true
+	}
+	// The number of active regions should be more than total region of all stores * collectFactor
+	if float64(c.GetRegionCount())*collectFactor > float64(checker.sum) {
+		return false
+	}
+	for _, store := range c.GetStores() {
+		if !store.IsPreparing() && !store.IsServing() {
+			continue
+		}
+		storeID := store.GetID()
+		// For each store, the number of active regions should be more than total region of the store * collectFactor
+		if float64(c.GetStoreRegionCount(storeID))*collectFactor > float64(checker.reactiveRegions[storeID]) {
+			return false
+		}
+	}
+	checker.prepared = true
+	return true
+}
+
+func (checker *prepareChecker) collect(region *core.RegionInfo) {
+	checker.Lock()
+	defer checker.Unlock()
+	for _, p := range region.GetPeers() {
+		checker.reactiveRegions[p.GetStoreId()]++
+	}
+	checker.sum++
+}
+
+func (checker *prepareChecker) isPrepared() bool {
+	checker.RLock()
+	defer checker.RUnlock()
+	return checker.prepared
+}