use sync.Pool to reduce gc presure on hot path

ast/flag_test.go

@@ -33,7 +33,7 @@ type testFlagSuite struct {
 }
 
 func (ts *testFlagSuite) SetUpSuite(c *C) {
-	ts.Parser = parser.New()
+	ts.Parser = parser.NewParser()
 }
 
 func (ts *testFlagSuite) TestHasAggFlag(c *C) {

ast/format_test.go

@@ -84,7 +84,7 @@ func (ts *testAstFormatSuite) TestAstFormat(c *C) {
 	for _, tt := range testcases {
 		expr := fmt.Sprintf("select %s", tt.input)
 		charset, collation := getDefaultCharsetAndCollate()
-		stmts, err := parser.New().Parse(expr, charset, collation)
+		stmts, err := parser.NewParser().Parse(expr, charset, collation)
 		node := stmts[0].(*ast.SelectStmt).Fields.Fields[0].Expr
 		c.Assert(err, IsNil)
 

ast/misc_test.go

@@ -97,7 +97,7 @@ jobAbbr char(4) not null,
 constraint foreign key (jobabbr) references ffxi_jobtype (jobabbr) on delete cascade on update cascade
 );
 `
-	parse := parser.New()
+	parse := parser.NewParser()
 	stmts, err := parse.Parse(sql, "", "")
 	c.Assert(err, IsNil)
 	for _, stmt := range stmts {
@@ -116,7 +116,7 @@ update t1 set col1 = col1 + 1, col2 = col1;
 show create table t;
 load data infile '/tmp/t.csv' into table t fields terminated by 'ab' enclosed by 'b';`
 
-	p := parser.New()
+	p := parser.NewParser()
 	stmts, err := p.Parse(sql, "", "")
 	c.Assert(err, IsNil)
 	for _, stmt := range stmts {

bootstrap_test.go

@@ -115,7 +115,7 @@ func globalVarsCount() int64 {
 func (s *testBootstrapSuite) bootstrapWithOnlyDDLWork(store kv.Storage, c *C) {
 	ss := &session{
 		store:       store,
-		parser:      parser.New(),
+		parser:      parser.NewParser(),
 		sessionVars: variable.NewSessionVars(),
 	}
 	ss.mu.values = make(map[fmt.Stringer]interface{})

cmd/importer/parser.go

@@ -219,7 +219,7 @@ func parseTable(t *table, stmt *ast.CreateTableStmt) error {
 }
 
 func parseTableSQL(table *table, sql string) error {
-	stmt, err := parser.New().ParseOneStmt(sql, "", "")
+	stmt, err := parser.NewParser().ParseOneStmt(sql, "", "")
 	if err != nil {
 		return errors.Trace(err)
 	}
@@ -256,7 +256,7 @@ func parseIndexSQL(table *table, sql string) error {
 		return nil
 	}
 
-	stmt, err := parser.New().ParseOneStmt(sql, "", "")
+	stmt, err := parser.NewParser().ParseOneStmt(sql, "", "")
 	if err != nil {
 		return errors.Trace(err)
 	}

ddl/column_test.go

@@ -926,7 +926,7 @@ func (s *testColumnSuite) TestModifyColumn(c *C) {
 
 func (s *testColumnSuite) colDefStrToFieldType(c *C, str string) *types.FieldType {
 	sqlA := "alter table t modify column a " + str
-	stmt, err := parser.New().ParseOneStmt(sqlA, "", "")
+	stmt, err := parser.NewParser().ParseOneStmt(sqlA, "", "")
 	c.Assert(err, IsNil)
 	colDef := stmt.(*ast.AlterTableStmt).Specs[0].NewColumns[0]
 	col, _, err := buildColumnAndConstraint(nil, 0, colDef)

ddl/ddl_db_change_test.go

@@ -57,7 +57,7 @@ func (s *testStateChangeSuite) SetUpSuite(c *C) {
 	c.Assert(err, IsNil)
 	_, err = s.se.Execute(goctx.Background(), "use test_db_state")
 	c.Assert(err, IsNil)
-	s.p = parser.New()
+	s.p = parser.NewParser()
 }
 
 func (s *testStateChangeSuite) TearDownSuite(c *C) {

executor/executor_test.go

@@ -78,7 +78,7 @@ var mockTikv = flag.Bool("mockTikv", true, "use mock tikv store in executor test
 func (s *testSuite) SetUpSuite(c *C) {
 	s.autoIDStep = autoid.GetStep()
 	autoid.SetStep(5000)
-	s.Parser = parser.New()
+	s.Parser = parser.NewParser()
 	flag.Lookup("mockTikv")
 	useMockTikv := *mockTikv
 	if useMockTikv {

executor/metrics_test.go

@@ -58,7 +58,7 @@ func (s *testSuite) TestStmtLabel(c *C) {
 	}
 	var ignore bool
 	for _, tt := range tests {
-		stmtNode, err := parser.New().ParseOneStmt(tt.sql, "", "")
+		stmtNode, err := parser.NewParser().ParseOneStmt(tt.sql, "", "")
 		c.Check(err, IsNil)
 		is := executor.GetInfoSchema(tk.Se)
 		err = plan.Preprocess(tk.Se.(context.Context), stmtNode, is, false)

executor/prepared.go

@@ -120,7 +120,7 @@ func (e *PrepareExec) DoPrepare() error {
 	if sqlParser, ok := e.ctx.(sqlexec.SQLParser); ok {
 		stmts, err = sqlParser.ParseSQL(e.sqlText, charset, collation)
 	} else {
-		stmts, err = parser.New().Parse(e.sqlText, charset, collation)
+		stmts, err = parser.NewParser().Parse(e.sqlText, charset, collation)
 	}
 	if err != nil {
 		return errors.Trace(err)

expression/aggregation/agg_to_pb_test.go

@@ -106,7 +106,7 @@ type testEvaluatorSuite struct {
 }
 
 func (s *testEvaluatorSuite) SetUpSuite(c *C) {
-	s.Parser = parser.New()
+	s.Parser = parser.NewParser()
 	s.ctx = mock.NewContext()
 }
 

expression/evaluator_test.go

@@ -41,7 +41,7 @@ type testEvaluatorSuite struct {
 }
 
 func (s *testEvaluatorSuite) SetUpSuite(c *C) {
-	s.Parser = parser.New()
+	s.Parser = parser.NewParser()
 	s.ctx = mock.NewContext()
 	s.ctx.GetSessionVars().StmtCtx.TimeZone = time.Local
 }

expression/typeinfer_test.go

@@ -52,7 +52,7 @@ type testInferTypeSuite struct {
 }
 
 func (s *testInferTypeSuite) SetUpSuite(c *C) {
-	s.Parser = parser.New()
+	s.Parser = parser.NewParser()
 }
 
 func (s *testInferTypeSuite) TearDownSuite(c *C) {

mysql/const_test.go

@@ -46,7 +46,7 @@ type testMySQLConstSuite struct {
 var mockTikv = flag.Bool("mockTikv", true, "use mock tikv store in executor test")
 
 func (s *testMySQLConstSuite) SetUpSuite(c *C) {
-	s.Parser = parser.New()
+	s.Parser = parser.NewParser()
 	flag.Lookup("mockTikv")
 	useMockTikv := *mockTikv
 	if useMockTikv {

new_session_test.go

@@ -339,7 +339,7 @@ func (s *testSessionSuite) TestRetryCleanTxn(c *C) {
 
 	// Hijack retry history, add a statement that returns error.
 	history := tidb.GetHistory(tk.Se)
-	stmtNode, err := parser.New().ParseOneStmt("insert retrytxn values (2, 'a')", "", "")
+	stmtNode, err := parser.NewParser().ParseOneStmt("insert retrytxn values (2, 'a')", "", "")
 	c.Assert(err, IsNil)
 	stmt, _ := tidb.Compile(goctx.TODO(), tk.Se, stmtNode)
 	executor.ResetStmtCtx(tk.Se, stmtNode)

parser/bench_test.go

@@ -17,34 +17,103 @@ import (
 	"testing"
 )
 
-func BenchmarkSysbenchSelect(b *testing.B) {
-	parser := New()
-	sql := "SELECT pad FROM sbtest1 WHERE id=1;"
-	b.ResetTimer()
-	for i := 0; i < b.N; i++ {
+func sysebchSelect(parser *Parser, sql string, num int, b *testing.B) {
+	for i := 0; i < num; i++ {
 		_, err := parser.Parse(sql, "", "")
 		if err != nil {
 			b.Fatal(err)
 		}
 	}
+}
+
+func BenchmarkSysbenchSelect1024(b *testing.B) {
+	parser := NewParser()
+	sql := "SELECT pad FROM sbtest1 WHERE id=1;"
+	b.ResetTimer()
+	for i := 0; i < b.N; i++ {
+		sysebchSelect(parser, sql, 1024, b)
+	}
+	b.ReportAllocs()
+}
+
+func BenchmarkSysbenchSelect256(b *testing.B) {
+	parser := NewParser()
+	sql := "SELECT pad FROM sbtest1 WHERE id=1;"
+	b.ResetTimer()
+	for i := 0; i < b.N; i++ {
+		sysebchSelect(parser, sql, 256, b)
+	}
+	b.ReportAllocs()
+}
+
+func BenchmarkSysbenchSelect128(b *testing.B) {
+	parser := NewParser()
+	sql := "SELECT pad FROM sbtest1 WHERE id=1;"
+	b.ResetTimer()
+	for i := 0; i < b.N; i++ {
+		sysebchSelect(parser, sql, 128, b)
+	}
+	b.ReportAllocs()
+}
+
+func BenchmarkParseInt4096(b *testing.B) {
+	parser := NewParser()
+	b.ResetTimer()
+	for i := 0; i < b.N; i++ {
+		for _, v := range table {
+			parseInt(parser, v, 4096, b)
+		}
+	}
+	b.ReportAllocs()
+}
+
+func BenchmarkParseInt1024(b *testing.B) {
+	parser := NewParser()
+	b.ResetTimer()
+	for i := 0; i < b.N; i++ {
+		for _, v := range table {
+			parseInt(parser, v, 1024, b)
+		}
+	}
+	b.ReportAllocs()
+}
+
+var table = []string{
+	"insert into t values (1), (2), (3)",
+	"insert into t values (4), (5), (6), (7)",
+	"select c from t where c > 2",
+	"select c from t where c > 1234567890123456789012345678901234567890.0;",
+}
+
+func BenchmarkParseInt512(b *testing.B) {
+	parser := NewParser()
+	b.ResetTimer()
+	for i := 0; i < b.N; i++ {
+		for _, v := range table {
+			parseInt(parser, v, 512, b)
+		}
+
+	}
 	b.ReportAllocs()
 }
 
-func BenchmarkParse(b *testing.B) {
-	var table = []string{
-		"insert into t values (1), (2), (3)",
-		"insert into t values (4), (5), (6), (7)",
-		"select c from t where c > 2",
+func parseInt(parser *Parser, sql string, num int, b *testing.B) {
+	for i := 0; i < num; i++ {
+		_, err := parser.Parse(sql, "", "")
+		if err != nil {
+			b.Failed()
+		}
 	}
-	parser := New()
+}
+
+func BenchmarkParseInt256(b *testing.B) {
+	parser := NewParser()
 	b.ResetTimer()
 	for i := 0; i < b.N; i++ {
 		for _, v := range table {
-			_, err := parser.Parse(v, "", "")
-			if err != nil {
-				b.Failed()
-			}
+			parseInt(parser, v, 256, b)
 		}
+
 	}
 	b.ReportAllocs()
 }

parser/lexer.go

@@ -97,7 +97,8 @@ func (s *Scanner) reset(sql string) {
 }
 
 func (s *Scanner) stmtText() string {
-	endPos := s.r.pos().Offset
+	var endPos int
+	endPos = s.r.pos().Offset
 	if s.r.s[endPos-1] == '\n' {
 		endPos = endPos - 1 // trim new line
 	}
@@ -134,9 +135,8 @@ func (s *Scanner) Lex(v *yySymType) int {
 	v.ident = lit
 	if tok == identifier {
 		tok = handleIdent(v)
-	}
-	if tok == identifier {
-		if tok1 := s.isTokenIdentifier(lit, pos.Offset); tok1 != 0 {
+		var tok1 int
+		if tok1 = s.isTokenIdentifier(lit, pos.Offset); tok1 != 0 {
 			tok = tok1
 		}
 	}