Add a switch for perfschema (pingcap#1390)

Add a switch for perfschema and disable it by default. You can enable perfschema by set tidb-server flag.
R1ckyZhang · Jul 5, 2016 · 4e177d3 · 4e177d3
1 parent 5520e26
commit 4e177d3
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Showing 5 changed files with 41 additions and 1 deletion.
diff --git a/perfschema/perfschema.go b/perfschema/perfschema.go
@@ -58,7 +58,17 @@ type perfSchema struct {
 	stmtInfos   map[reflect.Type]*statementInfo
 }
 
-var _ PerfSchema = (*perfSchema)(nil)
+var (
+	_ PerfSchema = (*perfSchema)(nil)
+
+	// perfschema is disabled by default to avoid performance consuming.
+	enablePerfSchema = false
+)
+
+// EnablePerfSchema enables perfschema.
+func EnablePerfSchema() {
+	enablePerfSchema = true
+}
 
 // NewPerfHandle creates a new perfSchema on store.
 func NewPerfHandle() (PerfSchema, error) {

diff --git a/perfschema/perfschema_test.go b/perfschema/perfschema_test.go
@@ -21,6 +21,7 @@ import (
 
 	. "github.com/pingcap/check"
 	"github.com/pingcap/tidb"
+	"github.com/pingcap/tidb/perfschema"
 	"github.com/pingcap/tidb/util/testleak"
 )
 
@@ -36,6 +37,10 @@ var _ = Suite(&testPerfSchemaSuit{
 	vars: make(map[string]interface{}),
 })
 
+func (s *testPerfSchemaSuit) SetUpSuite(c *C) {
+	perfschema.EnablePerfSchema()
+}
+
 func mustBegin(c *C, currDB *sql.DB) *sql.Tx {
 	tx, err := currDB.Begin()
 	c.Assert(err, IsNil)

diff --git a/perfschema/statement.go b/perfschema/statement.go
@@ -113,6 +113,9 @@ func (ps *perfSchema) RegisterStatement(category, name string, elem interface{})
 }
 
 func (ps *perfSchema) StartStatement(sql string, connID uint64, callerName EnumCallerName, elem interface{}) *StatementState {
+	if !enablePerfSchema {
+		return nil
+	}
 	stmtType := reflect.TypeOf(elem)
 	info, ok := ps.stmtInfos[stmtType]
 	if !ok {
@@ -176,6 +179,9 @@ func (ps *perfSchema) StartStatement(sql string, connID uint64, callerName EnumC
 }
 
 func (ps *perfSchema) EndStatement(state *StatementState) {
+	if !enablePerfSchema {
+		return
+	}
 	if state == nil {
 		return
 	}

diff --git a/perfschema/statement_test.go b/perfschema/statement_test.go
@@ -15,6 +15,7 @@ package perfschema
 
 import (
 	. "github.com/pingcap/check"
+	"github.com/pingcap/tidb/ast"
 	"github.com/pingcap/tidb/util/testleak"
 	"github.com/pingcap/tidb/util/types"
 )
@@ -36,3 +37,14 @@ func (p *testStatementSuit) TestUninitPS(c *C) {
 	err = ps.appendEventsStmtsHistory([]types.Datum{})
 	c.Assert(err, IsNil)
 }
+
+func (p *testStatementSuit) TestDisablePS(c *C) {
+	defer testleak.AfterTest(c)()
+	ps, err := NewPerfHandle()
+	c.Assert(err, IsNil)
+	s := ps.StartStatement("select * from t", uint64(1), CallerNameSessionExecute, &ast.SelectStmt{})
+	c.Assert(s, IsNil)
+	EnablePerfSchema()
+	s = ps.StartStatement("select * from t", uint64(1), CallerNameSessionExecute, &ast.SelectStmt{})
+	c.Assert(s, NotNil)
+}
diff --git a/tidb-server/main.go b/tidb-server/main.go
@@ -26,6 +26,7 @@ import (
 	"github.com/ngaut/log"
 	"github.com/pingcap/tidb"
 	"github.com/pingcap/tidb/metric"
+	"github.com/pingcap/tidb/perfschema"
 	"github.com/pingcap/tidb/server"
 	"github.com/pingcap/tidb/store/localstore/boltdb"
 	"github.com/pingcap/tidb/store/tikv"
@@ -40,6 +41,7 @@ var (
 	statusPort = flag.String("status", "10080", "tidb server status port")
 	lease      = flag.Int("lease", 1, "schema lease seconds, very dangerous to change only if you know what you do")
 	socket     = flag.String("socket", "", "The socket file to use for connection.")
+	enablePS   = flag.Int("perfschema", 0, "If enable performance schema.")
 )
 
 func main() {
@@ -70,6 +72,11 @@ func main() {
 	if err != nil {
 		log.Fatal(errors.ErrorStack(err))
 	}
+
+	if *enablePS == 1 {
+		perfschema.EnablePerfSchema()
+	}
+
 	// Create a session to load information schema.
 	se, err := tidb.CreateSession(store)
 	if err != nil {