ddl: release memory cache for all tidb-servers when unlock tables (pi…

…ngcap#21006) Signed-off-by: Shuaipeng Yu <jackysp@gmail.com>
sticnarf · Nov 13, 2020 · 975bbaf · 975bbaf
1 parent 5aada1f
commit 975bbaf
Show file tree

Hide file tree

Showing 3 changed files with 31 additions and 1 deletion.
diff --git a/ddl/ddl_api.go b/ddl/ddl_api.go
@@ -5420,7 +5420,6 @@ func (d *ddl) UnlockTables(ctx sessionctx.Context, unlockTables []model.TableLoc
 	err := d.doDDLJob(ctx, job)
 	if err == nil {
 		ctx.ReleaseAllTableLocks()
-		ctx.GetStore().GetMemCache().Release()
 	}
 	err = d.callHookOnChanged(err)
 	return errors.Trace(err)

diff --git a/domain/schema_validator.go b/domain/schema_validator.go
@@ -18,6 +18,7 @@ import (
 	"sync"
 	"time"
 
+	"github.com/pingcap/parser/model"
 	"github.com/pingcap/tidb/infoschema"
 	"github.com/pingcap/tidb/metrics"
 	"github.com/pingcap/tidb/sessionctx/variable"
@@ -153,6 +154,13 @@ func (s *schemaValidator) Update(leaseGrantTS uint64, oldVer, currVer int64, cha
 			tblIDs = change.PhyTblIDS
 			actionTypes = change.ActionTypes
 		}
+		for _, ac := range actionTypes {
+			// NOTE: ac is not an action type, it is (1 << action type).
+			if ac == 1<<model.ActionUnlockTable {
+				// TODO: If we could unlock only one table, we should release parts of the cache.
+				s.do.Store().GetMemCache().Release()
+			}
+		}
 		logutil.BgLogger().Debug("update schema validator", zap.Int64("oldVer", oldVer),
 			zap.Int64("currVer", currVer), zap.Int64s("changedTableIDs", tblIDs), zap.Uint64s("changedActionTypes", actionTypes))
 	}

diff --git a/executor/point_get_test.go b/executor/point_get_test.go
@@ -624,6 +624,29 @@ func (s *testPointGetSuite) TestPointGetReadLock(c *C) {
 	c.Assert(len(rows), Equals, 1)
 	explain = fmt.Sprintf("%v", rows[0])
 	c.Assert(explain, Matches, ".*num_rpc.*")
+
+	// Test cache release after unlocking tables.
+	tk.MustExec("lock tables point read")
+	rows = tk.MustQuery("explain analyze select * from point where id = 1").Rows()
+	c.Assert(len(rows), Equals, 1)
+	explain = fmt.Sprintf("%v", rows[0])
+	c.Assert(explain, Matches, ".*num_rpc.*")
+
+	rows = tk.MustQuery("explain analyze select * from point where id = 1").Rows()
+	c.Assert(len(rows), Equals, 1)
+	explain = fmt.Sprintf("%v", rows[0])
+	ok = strings.Contains(explain, "num_rpc")
+	c.Assert(ok, IsFalse)
+
+	tk.MustExec("unlock tables")
+	tk.MustExec("lock tables point read")
+
+	rows = tk.MustQuery("explain analyze select * from point where id = 1").Rows()
+	c.Assert(len(rows), Equals, 1)
+	explain = fmt.Sprintf("%v", rows[0])
+	c.Assert(explain, Matches, ".*num_rpc.*")
+
+	tk.MustExec("unlock tables")
 }
 
 func (s *testPointGetSuite) TestPointGetWriteLock(c *C) {