Index: src/kudu/master/auto_leader_rebalancer.cc
IDEA additional info:
Subsystem: com.intellij.openapi.diff.impl.patch.CharsetEP
<+>UTF-8
===================================================================
diff --git a/src/kudu/master/auto_leader_rebalancer.cc b/src/kudu/master/auto_leader_rebalancer.cc
--- a/src/kudu/master/auto_leader_rebalancer.cc	(revision 909b5676bff20400628a2338f0087940fa3bc524)
+++ b/src/kudu/master/auto_leader_rebalancer.cc	(revision d2a611fa8102e62d407f7eff3b3a2280e2d3518d)
@@ -201,6 +201,16 @@
   map<string, std::pair<int32_t, int32_t>> replica_and_leader_count_by_ts_uuid;
   // uuid->leader should transfer count
   map<string, int32_t> leader_transfer_source;
+  uint32_t remain_tablets_num = tablet_infos.size();
+  uint32_t remain_tservers = tserver_uuids.size();
+  // Get the exact num of tablet servers who will take a part in the leader rebalance.
+  for (const auto& uuid : tserver_uuids) {
+    auto* tablet_ids_ptr = FindOrNull(tablet_ids_by_ts_uuid, uuid);
+    uint32_t replica_count = tablet_ids_ptr ? tablet_ids_ptr->size() : 0;
+    if (replica_count == 0) {
+      remain_tservers --;
+    }
+  }
   for (const auto& uuid : tserver_uuids) {
     auto* tablet_ids_ptr = FindOrNull(tablet_ids_by_ts_uuid, uuid);
     uint32_t replica_count = tablet_ids_ptr ? tablet_ids_ptr->size() : 0;
@@ -215,15 +225,26 @@
     VLOG(1) << Substitute(
         "uuid: $0, replica_count: $1, leader_count: $2", uuid, replica_count, leader_count);
 
-    // Our target is every tserver' replicas, number of leader : number of follower is
-    // 1 : (replica_refactor -1). The constant 1 is a coarse-grained correction factor to help
-    // leader rebalancer to converge stable.
-    int32_t should_transfer_count = static_cast<int32_t>(leader_count) -
-                                    (static_cast<int32_t>(replica_count) / replication_factor + 1);
+    // If the remaining tablets could be divided by the remaining tablet servers,
+    // the leader num of all the remaining tablet servers should be the division
+    // result.
+    // Else, The maximum leader num of a tablet server should be the ceil value
+    // of average leaders num. Transfer the excess leaders if a tablet server have
+    // leaders more than that.
+    int32_t expect_leader_count;
+    if (remain_tablets_num % remain_tservers == 0) {
+      expect_leader_count = remain_tablets_num / tserver_uuids.size();
+    } else {
+      expect_leader_count = std::ceil(remain_tablets_num /
+          static_cast<double_t>(remain_tservers));
+    }
+    int32_t should_transfer_count = leader_count - expect_leader_count;
     if (should_transfer_count > 0) {
       leader_transfer_source.insert({uuid, should_transfer_count});
       VLOG(1) << Substitute("$0 should transfer leader count: $1", uuid, should_transfer_count);
     }
+    remain_tablets_num -= expect_leader_count;
+    remain_tservers--;
   }
 
   // Step 3.
@@ -383,7 +404,10 @@
   // we get all tserver uuids
   TSDescriptorVector descriptors;
   ts_manager_->GetAllDescriptors(&descriptors);
-
+  if (PREDICT_FALSE(descriptors.empty())) {
+    LOG(INFO) << "No tserver registered for now, skipping this loop.";
+    return Status::OK();
+  }
   vector<string> tserver_uuids;
   for (const auto& e : descriptors) {
     if (e->PresumedDead()) {