perfschema: fixed concurrent map bug (pingcap#1160)

perfschema/init.go

@@ -333,7 +333,7 @@ var setupTimersRecords [][]types.Datum
 func (ps *perfSchema) initialize() (err error) {
 	ps.tables = make(map[string]*model.TableInfo)
 	ps.mTables = make(map[string]table.Table, len(ps.tables))
-	ps.stmtHandles = make(map[uint64]int64)
+	ps.stmtHandles = make([]int64, currentElemMax)
 
 	allColDefs := [][]columnInfo{
 		setupActorsCols,

perfschema/perfschema.go

@@ -53,7 +53,7 @@ type perfSchema struct {
 	dbInfo      *model.DBInfo
 	tables      map[string]*model.TableInfo
 	mTables     map[string]table.Table // Memory tables for perfSchema
-	stmtHandles map[uint64]int64
+	stmtHandles []int64
 }
 
 var _ PerfSchema = (*perfSchema)(nil)

perfschema/statement.go

@@ -17,6 +17,7 @@ import (
 	"fmt"
 	"reflect"
 	"runtime"
+	"sync/atomic"
 	"time"
 
 	"github.com/juju/errors"
@@ -253,13 +254,14 @@ func (ps *perfSchema) updateEventsStmtsCurrent(connID uint64, record []types.Dat
 	if tbl == nil {
 		return nil
 	}
-	handle, ok := ps.stmtHandles[connID]
-	if !ok {
+	index := connID % uint64(currentElemMax)
+	handle := atomic.LoadInt64(&ps.stmtHandles[index])
+	if handle == 0 {
 		newHandle, err := tbl.AddRecord(nil, record)
 		if err != nil {
 			return errors.Trace(err)
 		}
-		ps.stmtHandles[connID] = newHandle
+		atomic.StoreInt64(&ps.stmtHandles[index], newHandle)
 		return nil
 	}
 	err := tbl.UpdateRecord(nil, handle, nil, record, nil)

table/tables/bounded_tables.go

@@ -35,6 +35,10 @@ const (
 	invalidRecordID int64 = 0
 )
 
+var (
+	errOpNotSupported = errors.New("Operation not supported")
+)
+
 type boundedItem struct {
 	handle int64
 	data   []types.Datum
@@ -263,7 +267,7 @@ func (t *BoundedTable) LockRow(ctx context.Context, h int64, forRead bool) error
 // RemoveRecord implements table.Table RemoveRecord interface.
 func (t *BoundedTable) RemoveRecord(ctx context.Context, h int64, r []types.Datum) error {
 	// not supported, BoundedTable is TRUNCATE only
-	return nil
+	return errOpNotSupported
 }
 
 // AllocAutoID implements table.Table AllocAutoID interface.