checker(dm): add a worker pool to concurrently working

dm/checker/checker.go

@@ -169,35 +169,6 @@ func (c *Checker) getTablePairInfo(ctx context.Context) (info *tablePairInfo, er
 		return nil, egErr
 	}
 
-	if _, ok := c.checkingItems[config.LightningFreeSpaceChecking]; ok &&
-		c.stCfgs[0].LoaderConfig.ImportMode == config.LoadModePhysical &&
-		c.stCfgs[0].Mode != config.ModeIncrement {
-		// TODO: concurrently read it intra-source later
-		for idx := range c.instances {
-			i := idx
-			eg.Go(func() error {
-				for _, sourceTables := range tableMapPerUpstream[i] {
-					for _, sourceTable := range sourceTables {
-						size, err2 := conn.FetchTableEstimatedBytes(
-							ctx,
-							c.instances[i].sourceDB,
-							sourceTable.Schema,
-							sourceTable.Name,
-						)
-						if err2 != nil {
-							return err2
-						}
-						info.totalDataSize.Add(size)
-					}
-				}
-				return nil
-			})
-		}
-	}
-	if egErr := eg.Wait(); egErr != nil {
-		return nil, egErr
-	}
-
 	info.targetTable2ExtendedColumns = extendedColumnPerTable
 	info.targetTable2SourceTablesMap = make(map[filter.Table]map[string][]filter.Table)
 	info.targetTableShardNum = make(map[filter.Table]int)
@@ -226,6 +197,8 @@ func (c *Checker) getTablePairInfo(ctx context.Context) (info *tablePairInfo, er
 	info.sourceID2SourceTables = make(map[string][]filter.Table, len(c.instances))
 	info.sourceID2InterestedDB = make([]map[string]struct{}, len(c.instances))
 	info.sourceID2TableMap = make(map[string]map[filter.Table][]filter.Table, len(c.instances))
+	sourceIDs := make([]string, 0, len(c.instances))
+	dbs := make(map[string]*conn.BaseDB, len(c.instances))
 	for i, inst := range c.instances {
 		sourceID := inst.cfg.SourceID
 		info.sourceID2InterestedDB[i] = make(map[string]struct{})
@@ -237,7 +210,55 @@ func (c *Checker) getTablePairInfo(ctx context.Context) (info *tablePairInfo, er
 				info.sourceID2InterestedDB[i][table.Schema] = struct{}{}
 			}
 		}
+		sourceIDs = append(sourceIDs, sourceID)
+		dbs[sourceID] = inst.sourceDB
 	}
+
+	if _, ok := c.checkingItems[config.LightningFreeSpaceChecking]; ok &&
+		c.stCfgs[0].LoaderConfig.ImportMode == config.LoadModePhysical &&
+		c.stCfgs[0].Mode != config.ModeIncrement {
+		concurrency, err := checker.GetConcurrency(ctx, sourceIDs, dbs, c.stCfgs[0].MydumperConfig.Threads)
+		if err != nil {
+			return nil, err
+		}
+
+		type job struct {
+			db     *conn.BaseDB
+			schema string
+			table  string
+		}
+
+		pool := checker.NewWorkerPoolWithContext[job, int64](ctx, func(result int64) {
+			info.totalDataSize.Add(result)
+		})
+		for i := 0; i < concurrency; i++ {
+			pool.Go(func(ctx context.Context, job job) (int64, error) {
+				return conn.FetchTableEstimatedBytes(
+					ctx,
+					job.db,
+					job.schema,
+					job.table,
+				)
+			})
+		}
+
+		for idx := range c.instances {
+			for _, sourceTables := range tableMapPerUpstream[idx] {
+				for _, sourceTable := range sourceTables {
+					pool.PutJob(job{
+						db:     c.instances[idx].sourceDB,
+						schema: sourceTable.Schema,
+						table:  sourceTable.Name,
+					})
+				}
+			}
+		}
+		err2 := pool.Wait()
+		if err2 != nil {
+			return nil, err2
+		}
+	}
+
 	return info, nil
 }