*: add global variable tidb_schema_version_cache_limit to control infoschema cache size

domain/domain.go

@@ -1053,7 +1053,7 @@ func NewDomain(store kv.Storage, ddlLease time.Duration, statsLease time.Duratio
 		exit:                make(chan struct{}),
 		sysSessionPool:      newSessionPool(capacity, factory),
 		statsLease:          statsLease,
-		infoCache:           infoschema.NewCache(16),
+		infoCache:           infoschema.NewCache(int(variable.SchemaVersionCacheLimit.Load())),
 		slowQuery:           newTopNSlowQueries(config.GetGlobalConfig().InMemSlowQueryTopNNum, time.Hour*24*7, config.GetGlobalConfig().InMemSlowQueryRecentNum),
 		indexUsageSyncLease: idxUsageSyncLease,
 		dumpFileGcChecker:   &dumpFileGcChecker{gcLease: dumpFileGcLease, paths: []string{replayer.GetPlanReplayerDirName(), GetOptimizerTraceDirName(), GetExtractTaskDirName()}},

domain/sysvar_cache.go

@@ -158,5 +158,6 @@ func (do *Domain) rebuildSysVarCache(ctx sessionctx.Context) error {
 	defer do.sysVarCache.Unlock()
 	do.sysVarCache.session = newSessionCache
 	do.sysVarCache.global = newGlobalCache
+	do.infoCache.ReSize(int(variable.SchemaVersionCacheLimit.Load()))
 	return nil
 }

executor/set_test.go

@@ -880,6 +880,23 @@ func TestSetVar(t *testing.T) {
 	tk.MustQuery("select @@session.tidb_skip_missing_partition_stats").Check(testkit.Rows("0"))
 	tk.MustExec("set session tidb_skip_missing_partition_stats = 1")
 	tk.MustQuery("select @@session.tidb_skip_missing_partition_stats").Check(testkit.Rows("1"))
+
+	// test tidb_schema_version_cache_limit
+	tk.MustQuery("select @@global.tidb_schema_version_cache_limit").Check(testkit.Rows("16"))
+	tk.MustExec("set @@global.tidb_schema_version_cache_limit=64;")
+	tk.MustQuery("select @@global.tidb_schema_version_cache_limit").Check(testkit.Rows("64"))
+	tk.MustExec("set @@global.tidb_schema_version_cache_limit=2;")
+	tk.MustQuery("select @@global.tidb_schema_version_cache_limit").Check(testkit.Rows("2"))
+	tk.MustExec("set @@global.tidb_schema_version_cache_limit=256;")
+	tk.MustQuery("SHOW WARNINGS").Check(testkit.Rows("Warning 1292 Truncated incorrect tidb_schema_version_cache_limit value: '256'"))
+	tk.MustQuery("select @@global.tidb_schema_version_cache_limit").Check(testkit.Rows("255"))
+	tk.MustExec("set @@global.tidb_schema_version_cache_limit=0;")
+	tk.MustQuery("SHOW WARNINGS").Check(testkit.Rows("Warning 1292 Truncated incorrect tidb_schema_version_cache_limit value: '0'"))
+	tk.MustQuery("select @@global.tidb_schema_version_cache_limit").Check(testkit.Rows("2"))
+	tk.MustGetErrMsg("set @@global.tidb_schema_version_cache_limit='x';", "[variable:1232]Incorrect argument type to variable 'tidb_schema_version_cache_limit'")
+	tk.MustQuery("select @@global.tidb_schema_version_cache_limit").Check(testkit.Rows("2"))
+	tk.MustExec("set @@global.tidb_schema_version_cache_limit=64;")
+	tk.MustQuery("select @@global.tidb_schema_version_cache_limit").Check(testkit.Rows("64"))
 }
 
 func TestGetSetNoopVars(t *testing.T) {

infoschema/cache.go

@@ -44,6 +44,30 @@ func NewCache(capacity int) *InfoCache {
 	}
 }
 
+// ReSize re-size the cache.
+func (h *InfoCache) ReSize(capacity int) {
+	h.mu.Lock()
+	defer h.mu.Unlock()
+	if cap(h.cache) == capacity {
+		return
+	}
+	oldCache := h.cache
+	h.cache = make([]schemaAndTimestamp, 0, capacity)
+	for i, v := range oldCache {
+		if i >= capacity {
+			break
+		}
+		h.cache = append(h.cache, v)
+	}
+}
+
+// Size returns the size of the cache, export for test.
+func (h *InfoCache) Size() int {
+	h.mu.Lock()
+	defer h.mu.Unlock()
+	return len(h.cache)
+}
+
 // Reset resets the cache.
 func (h *InfoCache) Reset(capacity int) {
 	h.mu.Lock()

infoschema/test/cachetest/BUILD.bazel

@@ -8,7 +8,7 @@ go_test(
         "main_test.go",
     ],
     flaky = True,
-    shard_count = 5,
+    shard_count = 6,
     deps = [
         "//infoschema",
         "//testkit/testsetup",

infoschema/test/cachetest/cache_test.go

@@ -177,3 +177,37 @@ func TestGetByTimestamp(t *testing.T) {
 	require.Equal(t, is3, ic.GetBySnapshotTS(3))
 	require.Equal(t, 3, ic.Len())
 }
+
+func TestReSize(t *testing.T) {
+	ic := infoschema.NewCache(2)
+	require.NotNil(t, ic)
+	is1 := infoschema.MockInfoSchemaWithSchemaVer(nil, 1)
+	ic.Insert(is1, 1)
+	is2 := infoschema.MockInfoSchemaWithSchemaVer(nil, 2)
+	ic.Insert(is2, 2)
+
+	ic.ReSize(3)
+	require.Equal(t, 2, ic.Size())
+	require.Equal(t, is1, ic.GetByVersion(1))
+	require.Equal(t, is2, ic.GetByVersion(2))
+	is3 := infoschema.MockInfoSchemaWithSchemaVer(nil, 3)
+	require.True(t, ic.Insert(is3, 3))
+	require.Equal(t, is1, ic.GetByVersion(1))
+	require.Equal(t, is2, ic.GetByVersion(2))
+	require.Equal(t, is3, ic.GetByVersion(3))
+
+	ic.ReSize(1)
+	require.Equal(t, 1, ic.Size())
+	require.Nil(t, ic.GetByVersion(1))
+	require.Nil(t, ic.GetByVersion(2))
+	require.Equal(t, is3, ic.GetByVersion(3))
+	require.False(t, ic.Insert(is2, 2))
+	require.Equal(t, 1, ic.Size())
+	is4 := infoschema.MockInfoSchemaWithSchemaVer(nil, 4)
+	require.True(t, ic.Insert(is4, 4))
+	require.Equal(t, 1, ic.Size())
+	require.Nil(t, ic.GetByVersion(1))
+	require.Nil(t, ic.GetByVersion(2))
+	require.Nil(t, ic.GetByVersion(3))
+	require.Equal(t, is4, ic.GetByVersion(4))
+}

sessionctx/variable/sysvar.go

@@ -2852,6 +2852,11 @@ var defaultSysVars = []*SysVar{
 		}, GetGlobal: func(ctx context.Context, vars *SessionVars) (string, error) {
 			return ServiceScope.Load(), nil
 		}},
+	{Scope: ScopeGlobal, Name: TiDBSchemaVersionCacheLimit, Value: strconv.Itoa(DefTiDBSchemaVersionCacheLimit), Type: TypeInt, MinValue: 2, MaxValue: math.MaxUint8, AllowEmpty: true,
+		SetGlobal: func(_ context.Context, s *SessionVars, val string) error {
+			SchemaVersionCacheLimit.Store(TidbOptInt64(val, DefTiDBSchemaVersionCacheLimit))
+			return nil
+		}},
 }
 
 func setTiFlashComputeDispatchPolicy(s *SessionVars, val string) error {

sessionctx/variable/tidb_vars.go

@@ -1097,6 +1097,8 @@ const (
 	TiDBSessionAlias = "tidb_session_alias"
 	// TiDBServiceScope indicates the role for tidb for distributed task framework.
 	TiDBServiceScope = "tidb_service_scope"
+	// TiDBSchemaVersionCacheLimit defines the capacity size of domain infoSchema cache.
+	TiDBSchemaVersionCacheLimit = "tidb_schema_version_cache_limit"
 )
 
 // TiDB intentional limits
@@ -1404,6 +1406,7 @@ const (
 	DefTiDBEnableCheckConstraint                      = false
 	DefTiDBSkipMissingPartitionStats                  = true
 	DefTiDBOptObjective                               = OptObjectiveModerate
+	DefTiDBSchemaVersionCacheLimit                    = 16
 )
 
 // Process global variables.
@@ -1500,6 +1503,7 @@ var (
 	EnableCheckConstraint     = atomic.NewBool(DefTiDBEnableCheckConstraint)
 	SkipMissingPartitionStats = atomic.NewBool(DefTiDBSkipMissingPartitionStats)
 	ServiceScope              = atomic.NewString("")
+	SchemaVersionCacheLimit   = atomic.NewInt64(DefTiDBSchemaVersionCacheLimit)
 )
 
 var (