*: Optimize struct memory usage by adjust field order (#11629)

cmd/importer/data.go

@@ -31,8 +31,8 @@ type datum struct {
 	timeValue   time.Time
 	remains     uint64
 	repeats     uint64
-	probability uint32
 	step        int64
+	probability uint32
 
 	init     bool
 	useRange bool

config/config.go

@@ -174,11 +174,11 @@ func (s *Security) ToTLSConfig() (*tls.Config, error) {
 
 // Status is the status section of the config.
 type Status struct {
-	ReportStatus    bool   `toml:"report-status" json:"report-status"`
 	StatusHost      string `toml:"status-host" json:"status-host"`
-	StatusPort      uint   `toml:"status-port" json:"status-port"`
 	MetricsAddr     string `toml:"metrics-addr" json:"metrics-addr"`
+	StatusPort      uint   `toml:"status-port" json:"status-port"`
 	MetricsInterval uint   `toml:"metrics-interval" json:"metrics-interval"`
+	ReportStatus    bool   `toml:"report-status" json:"report-status"`
 	RecordQPSbyDB   bool   `toml:"record-db-qps" json:"record-db-qps"`
 }
 
@@ -186,10 +186,7 @@ type Status struct {
 type Performance struct {
 	MaxProcs            uint    `toml:"max-procs" json:"max-procs"`
 	MaxMemory           uint64  `toml:"max-memory" json:"max-memory"`
-	TCPKeepAlive        bool    `toml:"tcp-keep-alive" json:"tcp-keep-alive"`
-	CrossJoin           bool    `toml:"cross-join" json:"cross-join"`
 	StatsLease          string  `toml:"stats-lease" json:"stats-lease"`
-	RunAutoAnalyze      bool    `toml:"run-auto-analyze" json:"run-auto-analyze"`
 	StmtCountLimit      uint    `toml:"stmt-count-limit" json:"stmt-count-limit"`
 	FeedbackProbability float64 `toml:"feedback-probability" json:"feedback-probability"`
 	QueryFeedbackLimit  uint    `toml:"query-feedback-limit" json:"query-feedback-limit"`
@@ -197,6 +194,9 @@ type Performance struct {
 	ForcePriority       string  `toml:"force-priority" json:"force-priority"`
 	BindInfoLease       string  `toml:"bind-info-lease" json:"bind-info-lease"`
 	TxnTotalSizeLimit   uint64  `toml:"txn-total-size-limit" json:"txn-total-size-limit"`
+	TCPKeepAlive        bool    `toml:"tcp-keep-alive" json:"tcp-keep-alive"`
+	CrossJoin           bool    `toml:"cross-join" json:"cross-join"`
+	RunAutoAnalyze      bool    `toml:"run-auto-analyze" json:"run-auto-analyze"`
 }
 
 // PlanCache is the PlanCache section of the config.
@@ -222,9 +222,9 @@ type PreparedPlanCache struct {
 // OpenTracing is the opentracing section of the config.
 type OpenTracing struct {
 	Enable     bool                `toml:"enable" json:"enable"`
+	RPCMetrics bool                `toml:"rpc-metrics" json:"rpc-metrics"`
 	Sampler    OpenTracingSampler  `toml:"sampler" json:"sampler"`
 	Reporter   OpenTracingReporter `toml:"reporter" json:"reporter"`
-	RPCMetrics bool                `toml:"rpc-metrics" json:"rpc-metrics"`
 }
 
 // OpenTracingSampler is the config for opentracing sampler.
@@ -285,11 +285,11 @@ type TiKVClient struct {
 
 // Binlog is the config for binlog.
 type Binlog struct {
-	Enable       bool   `toml:"enable" json:"enable"`
-	WriteTimeout string `toml:"write-timeout" json:"write-timeout"`
+	Enable bool `toml:"enable" json:"enable"`
 	// If IgnoreError is true, when writing binlog meets error, TiDB would
 	// ignore the error.
-	IgnoreError bool `toml:"ignore-error" json:"ignore-error"`
+	IgnoreError  bool   `toml:"ignore-error" json:"ignore-error"`
+	WriteTimeout string `toml:"write-timeout" json:"write-timeout"`
 	// Use socket file to write binlog, for compatible with kafka version tidb-binlog.
 	BinlogSocket string `toml:"binlog-socket" json:"binlog-socket"`
 	// The strategy for sending binlog to pump, value can be "range" or "hash" now.

ddl/ddl_worker_test.go

@@ -353,9 +353,9 @@ func checkCancelState(txn kv.Transaction, job *model.Job, test *testCancelJob) e
 }
 
 type testCancelJob struct {
-	act           model.ActionType // act is the job action.
 	jobIDs        []int64
-	cancelRetErrs []error // cancelRetErrs is the first return value of CancelJobs.
+	cancelRetErrs []error          // cancelRetErrs is the first return value of CancelJobs.
+	act           model.ActionType // act is the job action.
 	cancelState   model.SchemaState
 }
 

ddl/delete_range.go

@@ -55,14 +55,14 @@ type delRangeManager interface {
 }
 
 type delRange struct {
-	store        kv.Storage
-	sessPool     *sessionPool
-	storeSupport bool
-	emulatorCh   chan struct{}
-	keys         []kv.Key
-	quitCh       chan struct{}
+	store      kv.Storage
+	sessPool   *sessionPool
+	emulatorCh chan struct{}
+	keys       []kv.Key
+	quitCh     chan struct{}
 
-	wait sync.WaitGroup // wait is only used when storeSupport is false.
+	wait         sync.WaitGroup // wait is only used when storeSupport is false.
+	storeSupport bool
 }
 
 // newDelRangeManager returns a delRangeManager.

domain/domain.go

@@ -61,7 +61,6 @@ type Domain struct {
 	bindHandle           *bindinfo.BindHandle
 	statsHandle          unsafe.Pointer
 	statsLease           time.Duration
-	statsUpdating        sync2.AtomicInt32
 	ddl                  ddl.DDL
 	info                 *InfoSyncer
 	m                    sync.Mutex
@@ -69,10 +68,11 @@ type Domain struct {
 	sysSessionPool       *sessionPool
 	exit                 chan struct{}
 	etcdClient           *clientv3.Client
-	wg                   sync.WaitGroup
 	gvc                  GlobalVariableCache
 	slowQuery            *topNSlowQueries
 	expensiveQueryHandle *expensivequery.Handle
+	wg                   sync.WaitGroup
+	statsUpdating        sync2.AtomicInt32
 }
 
 // loadInfoSchema loads infoschema at startTS into handle, usedSchemaVersion is the currently used

domain/topn_slow_query.go

@@ -217,13 +217,13 @@ type SlowQueryInfo struct {
 	Start    time.Time
 	Duration time.Duration
 	Detail   execdetails.ExecDetails
-	Succ     bool
 	ConnID   uint64
 	TxnTS    uint64
 	User     string
 	DB       string
 	TableIDs string
 	IndexIDs string
-	Internal bool
 	Digest   string
+	Internal bool
+	Succ     bool
 }

executor/adapter.go

@@ -146,10 +146,6 @@ type ExecStmt struct {
 	InfoSchema infoschema.InfoSchema
 	// Plan stores a reference to the final physical plan.
 	Plan plannercore.Plan
-	// LowerPriority represents whether to lower the execution priority of a query.
-	LowerPriority bool
-	// Cacheable represents whether the physical plan can be cached.
-	Cacheable bool
 	// Text represents the origin query text.
 	Text string
 
@@ -157,7 +153,11 @@ type ExecStmt struct {
 
 	Ctx sessionctx.Context
 	// StartTime stands for the starting time when executing the statement.
-	StartTime         time.Time
+	StartTime time.Time
+	// LowerPriority represents whether to lower the execution priority of a query.
+	LowerPriority bool
+	// Cacheable represents whether the physical plan can be cached.
+	Cacheable         bool
 	isPreparedStmt    bool
 	isSelectForUpdate bool
 	retryCount        uint

executor/aggregate.go

@@ -132,7 +132,6 @@ type AfFinalResult struct {
 type HashAggExec struct {
 	baseExecutor
 
-	prepared         bool
 	sc               *stmtctx.StatementContext
 	PartialAggFuncs  []aggfuncs.AggFunc
 	FinalAggFuncs    []aggfuncs.AggFunc
@@ -144,10 +143,6 @@ type HashAggExec struct {
 	groupKeyBuffer   []byte
 	groupValDatums   []types.Datum
 
-	// After we support parallel execution for aggregation functions with distinct,
-	// we can remove this attribute.
-	isUnparallelExec bool
-
 	finishCh         chan struct{}
 	finalOutputCh    chan *AfFinalResult
 	finalInputCh     chan *chunk.Chunk
@@ -157,10 +152,14 @@ type HashAggExec struct {
 	partialWorkers   []HashAggPartialWorker
 	finalWorkers     []HashAggFinalWorker
 	defaultVal       *chunk.Chunk
+	childResult      *chunk.Chunk
+
 	// isChildReturnEmpty indicates whether the child executor only returns an empty input.
 	isChildReturnEmpty bool
-
-	childResult *chunk.Chunk
+	// After we support parallel execution for aggregation functions with distinct,
+	// we can remove this attribute.
+	isUnparallelExec bool
+	prepared         bool
 }
 
 // HashAggInput indicates the input of hash agg exec.

executor/executor.go

@@ -1240,14 +1240,14 @@ type UnionExec struct {
 	baseExecutor
 
 	stopFetchData atomic.Value
-	wg            sync.WaitGroup
 
 	finished      chan struct{}
 	resourcePools []chan *chunk.Chunk
 	resultPool    chan *unionWorkerResult
-	initialized   bool
 
 	childrenResults []*chunk.Chunk
+	wg              sync.WaitGroup
+	initialized     bool
 }
 
 // unionWorkerResult stores the result for a union worker.

executor/grant.go

@@ -46,10 +46,10 @@ type GrantExec struct {
 	ObjectType ast.ObjectTypeType
 	Level      *ast.GrantLevel
 	Users      []*ast.UserSpec
-	WithGrant  bool
 
-	is   infoschema.InfoSchema
-	done bool
+	is        infoschema.InfoSchema
+	WithGrant bool
+	done      bool
 }
 
 // Next implements the Executor Next interface.

executor/join.go

@@ -48,7 +48,6 @@ type HashJoinExec struct {
 	outerKeys   []*expression.Column
 	innerKeys   []*expression.Column
 
-	prepared bool
 	// concurrency is the number of partition, build and join workers.
 	concurrency     uint
 	hashTable       *mvmap.MVMap
@@ -58,10 +57,8 @@ type HashJoinExec struct {
 	joinWorkerWaitGroup sync.WaitGroup
 	finished            atomic.Value
 	// closeCh add a lock for closing executor.
-	closeCh  chan struct{}
-	joinType plannercore.JoinType
-
-	isOuterJoin  bool
+	closeCh      chan struct{}
+	joinType     plannercore.JoinType
 	requiredRows int64
 
 	// We build individual joiner for each join worker when use chunk-based
@@ -77,7 +74,9 @@ type HashJoinExec struct {
 	joinResultCh       chan *hashjoinWorkerResult
 	hashTableValBufs   [][][]byte
 
-	memTracker *memory.Tracker // track memory usage.
+	memTracker  *memory.Tracker // track memory usage.
+	prepared    bool
+	isOuterJoin bool
 }
 
 // outerChkResource stores the result of the join outer fetch worker,

executor/load_data.go

@@ -351,14 +351,14 @@ type field struct {
 
 type fieldWriter struct {
 	pos           int
+	ReadBuf       []byte
+	OutputBuf     []byte
 	enclosedChar  byte
 	fieldTermChar byte
 	term          string
 	isEnclosed    bool
 	isLineStart   bool
 	isFieldStart  bool
-	ReadBuf       []byte
-	OutputBuf     []byte
 }
 
 func (w *fieldWriter) Init(enclosedChar byte, fieldTermChar byte, readBuf []byte, term string) {

executor/prepared.go

@@ -205,10 +205,10 @@ type ExecuteExec struct {
 	is            infoschema.InfoSchema
 	name          string
 	usingVars     []expression.Expression
-	id            uint32
 	stmtExec      Executor
 	stmt          ast.StmtNode
 	plan          plannercore.Plan
+	id            uint32
 	lowerPriority bool
 }
 

executor/show.go

@@ -58,24 +58,23 @@ var etcdDialTimeout = 5 * time.Second
 type ShowExec struct {
 	baseExecutor
 
-	Tp          ast.ShowStmtType // Databases/Tables/Columns/....
-	DBName      model.CIStr
-	Table       *ast.TableName  // Used for showing columns.
-	Column      *ast.ColumnName // Used for `desc table column`.
-	IndexName   model.CIStr     // Used for show table regions.
-	Flag        int             // Some flag parsed from sql, such as FULL.
-	Full        bool
-	User        *auth.UserIdentity   // Used by show grants, show create user.
-	Roles       []*auth.RoleIdentity // Used for show grants.
-	IfNotExists bool                 // Used for `show create database if not exists`
-
-	// GlobalScope is used by show variables
-	GlobalScope bool
+	Tp        ast.ShowStmtType // Databases/Tables/Columns/....
+	DBName    model.CIStr
+	Table     *ast.TableName       // Used for showing columns.
+	Column    *ast.ColumnName      // Used for `desc table column`.
+	IndexName model.CIStr          // Used for show table regions.
+	Flag      int                  // Some flag parsed from sql, such as FULL.
+	Roles     []*auth.RoleIdentity // Used for show grants.
+	User      *auth.UserIdentity   // Used by show grants, show create user.
 
 	is infoschema.InfoSchema
 
 	result *chunk.Chunk
 	cursor int
+
+	Full        bool
+	IfNotExists bool // Used for `show create database if not exists`
+	GlobalScope bool // GlobalScope is used by show variables
 }
 
 // Next implements the Executor Next interface.

executor/table_reader.go

@@ -55,10 +55,8 @@ func (sr selectResultHook) SelectResult(ctx context.Context, sctx sessionctx.Con
 type TableReaderExecutor struct {
 	baseExecutor
 
-	table     table.Table
-	keepOrder bool
-	desc      bool
-	ranges    []*ranger.Range
+	table  table.Table
+	ranges []*ranger.Range
 	// kvRanges are only use for union scan.
 	kvRanges []kv.KeyRange
 	dagPB    *tipb.DAGRequest
@@ -68,18 +66,19 @@ type TableReaderExecutor struct {
 	// resultHandler handles the order of the result. Since (MAXInt64, MAXUint64] stores before [0, MaxInt64] physically
 	// for unsigned int.
 	resultHandler *tableResultHandler
-	streaming     bool
 	feedback      *statistics.QueryFeedback
+	plans         []plannercore.PhysicalPlan
 
+	memTracker       *memory.Tracker
+	selectResultHook // for testing
+
+	keepOrder bool
+	desc      bool
+	streaming bool
 	// corColInFilter tells whether there's correlated column in filter.
 	corColInFilter bool
 	// corColInAccess tells whether there's correlated column in access conditions.
 	corColInAccess bool
-	plans          []plannercore.PhysicalPlan
-
-	memTracker *memory.Tracker
-
-	selectResultHook // for testing
 }
 
 // Open initialzes necessary variables for using this executor.

expression/aggregation/concat.go

@@ -28,8 +28,8 @@ import (
 type concatFunction struct {
 	aggFunction
 	separator string
-	sepInited bool
 	maxLen    uint64
+	sepInited bool
 	// truncated according to MySQL, a 'group_concat' function generates exactly one 'truncated' warning during its life time, no matter
 	// how many group actually truncated. 'truncated' acts as a sentinel to indicate whether this warning has already been
 	// generated.

expression/column.go

@@ -163,16 +163,16 @@ type Column struct {
 	ID int64
 	// UniqueID is the unique id of this column.
 	UniqueID int64
-	// IsReferenced means if this column is referenced to an Aggregation column, or a Subquery column,
-	// or an argument column of function IfNull.
-	// If so, this column's name will be the plain sql text.
-	IsReferenced bool
 
 	// Index is used for execution, to tell the column's position in the given row.
 	Index int
 
 	hashcode []byte
 
+	// IsReferenced means if this column is referenced to an Aggregation column, or a Subquery column,
+	// or an argument column of function IfNull.
+	// If so, this column's name will be the plain sql text.
+	IsReferenced bool
 	// InOperand indicates whether this column is the inner operand of column equal condition converted
 	// from `[not] in (subq)`.
 	InOperand bool

infoschema/slow_log.go

@@ -184,7 +184,6 @@ type slowQueryTuple struct {
 	processKeys       uint64
 	db                string
 	indexIDs          string
-	isInternal        bool
 	digest            string
 	statsInfo         string
 	avgProcessTime    float64
@@ -196,8 +195,9 @@ type slowQueryTuple struct {
 	maxWaitTime       float64
 	maxWaitAddress    string
 	memMax            int64
-	succ              bool
 	sql               string
+	isInternal        bool
+	succ              bool
 }
 
 func (st *slowQueryTuple) setFieldValue(tz *time.Location, field, value string) error {

kv/kv.go

@@ -199,10 +199,7 @@ type Request struct {
 	StartTs   uint64
 	Data      []byte
 	KeyRanges []KeyRange
-	// KeepOrder is true, if the response should be returned in order.
-	KeepOrder bool
-	// Desc is true, if the request is sent in descending order.
-	Desc bool
+
 	// Concurrency is 1, if it only sends the request to a single storage unit when
 	// ResponseIterator.Next is called. If concurrency is greater than 1, the request will be
 	// sent to multiple storage units concurrently.
@@ -211,6 +208,12 @@ type Request struct {
 	IsolationLevel IsoLevel
 	// Priority is the priority of this KV request, its value may be PriorityNormal/PriorityLow/PriorityHigh.
 	Priority int
+	// MemTracker is used to trace and control memory usage in co-processor layer.
+	MemTracker *memory.Tracker
+	// KeepOrder is true, if the response should be returned in order.
+	KeepOrder bool
+	// Desc is true, if the request is sent in descending order.
+	Desc bool
 	// NotFillCache makes this request do not touch the LRU cache of the underlying storage.
 	NotFillCache bool
 	// SyncLog decides whether the WAL(write-ahead log) of this request should be synchronized.
@@ -218,8 +221,6 @@ type Request struct {
 	// Streaming indicates using streaming API for this request, result in that one Next()
 	// call would not corresponds to a whole region result.
 	Streaming bool
-	// MemTracker is used to trace and control memory usage in co-processor layer.
-	MemTracker *memory.Tracker
 }
 
 // ResultSubset represents a result subset from a single storage unit.

planner/core/common_plans.go

@@ -371,11 +371,11 @@ type Show struct {
 	Table       *ast.TableName  // Used for showing columns.
 	Column      *ast.ColumnName // Used for `desc table column`.
 	IndexName   model.CIStr
-	Flag        int // Some flag parsed from sql, such as FULL.
-	Full        bool
+	Flag        int                  // Some flag parsed from sql, such as FULL.
 	User        *auth.UserIdentity   // Used for show grants.
 	Roles       []*auth.RoleIdentity // Used for show grants.
-	IfNotExists bool                 // Used for `show create database if not exists`
+	Full        bool
+	IfNotExists bool // Used for `show create database if not exists`
 
 	GlobalScope bool // Used by show variables
 }

planner/core/physical_plans.go

@@ -98,11 +98,6 @@ type PhysicalIndexScan struct {
 	Ranges     []*ranger.Range
 	Columns    []*model.ColumnInfo
 	DBName     model.CIStr
-	Desc       bool
-	KeepOrder  bool
-	// DoubleRead means if the index executor will read kv two times.
-	// If the query requires the columns that don't belong to index, DoubleRead will be true.
-	DoubleRead bool
 
 	TableAsName *model.CIStr
 
@@ -117,10 +112,16 @@ type PhysicalIndexScan struct {
 	rangeInfo string
 
 	// The index scan may be on a partition.
-	isPartition     bool
 	physicalTableID int64
 
 	GenExprs map[model.TableColumnID]expression.Expression
+
+	isPartition bool
+	Desc        bool
+	KeepOrder   bool
+	// DoubleRead means if the index executor will read kv two times.
+	// If the query requires the columns that don't belong to index, DoubleRead will be true.
+	DoubleRead bool
 }
 
 // PhysicalMemTable reads memory table.
@@ -144,27 +145,27 @@ type PhysicalTableScan struct {
 	Table   *model.TableInfo
 	Columns []*model.ColumnInfo
 	DBName  model.CIStr
-	Desc    bool
 	Ranges  []*ranger.Range
 	pkCol   *expression.Column
 
 	TableAsName *model.CIStr
 
-	// KeepOrder is true, if sort data by scanning pkcol,
-	KeepOrder bool
-
 	// Hist is the histogram when the query was issued.
 	// It is used for query feedback.
 	Hist *statistics.Histogram
 
-	// The table scan may be a partition, rather than a real table.
-	isPartition     bool
 	physicalTableID int64
 
 	rangeDecidedBy []*expression.Column
 
 	// HandleIdx is the index of handle, which is only used for admin check table.
 	HandleIdx int
+
+	// The table scan may be a partition, rather than a real table.
+	isPartition bool
+	// KeepOrder is true, if sort data by scanning pkcol,
+	KeepOrder bool
+	Desc      bool
 }
 
 // IsPartition returns true and partition ID if it's actually a partition.

planner/core/planbuilder.go

@@ -173,7 +173,6 @@ type PlanBuilder struct {
 	ctx          sessionctx.Context
 	is           infoschema.InfoSchema
 	outerSchemas []*expression.Schema
-	inUpdateStmt bool
 	// colMapper stores the column that must be pre-resolved.
 	colMapper map[*ast.ColumnNameExpr]int
 	// visitInfo is used for privilege check.
@@ -188,11 +187,11 @@ type PlanBuilder struct {
 	rewriterPool    []*expressionRewriter
 	rewriterCounter int
 
+	windowSpecs  map[string]*ast.WindowSpec
+	inUpdateStmt bool
 	// inStraightJoin represents whether the current "SELECT" statement has
 	// "STRAIGHT_JOIN" option.
 	inStraightJoin bool
-
-	windowSpecs map[string]*ast.WindowSpec
 }
 
 // GetVisitInfo gets the visitInfo of the PlanBuilder.

planner/core/point_get_plan.go

@@ -43,11 +43,11 @@ type PointGetPlan struct {
 	IndexInfo        *model.IndexInfo
 	Handle           int64
 	HandleParam      *driver.ParamMarkerExpr
-	UnsignedHandle   bool
 	IndexValues      []types.Datum
 	IndexValueParams []*driver.ParamMarkerExpr
 	expr             expression.Expression
 	ctx              sessionctx.Context
+	UnsignedHandle   bool
 	IsTableDual      bool
 	Lock             bool
 	IsForUpdate      bool

plugin/plugin.go

@@ -96,9 +96,9 @@ type Config struct {
 type Plugin struct {
 	*Manifest
 	library  *gplugin.Plugin
-	State    State
 	Path     string
 	Disabled uint32
+	State    State
 }
 
 // StateValue returns readable state string.

plugin/spi.go

@@ -31,10 +31,8 @@ const (
 
 // Manifest describes plugin info and how it can do by plugin itself.
 type Manifest struct {
-	Kind           Kind
 	Name           string
 	Description    string
-	Version        uint16
 	RequireVersion map[string]uint16
 	License        string
 	BuildTime      string
@@ -54,6 +52,9 @@ type Manifest struct {
 	// return error will write log and continue watch following flush.
 	OnFlush      func(ctx context.Context, manifest *Manifest) error
 	flushWatcher *flushWatcher
+
+	Version uint16
+	Kind    Kind
 }
 
 // ExportManifest exports a manifest to TiDB as a known format.

server/conn.go

@@ -139,7 +139,6 @@ type clientConn struct {
 	server       *Server           // a reference of server instance.
 	capability   uint32            // client capability affects the way server handles client request.
 	connectionID uint32            // atomically allocated by a global variable, unique in process scope.
-	collation    uint8             // collation used by client, may be different from the collation used by database.
 	user         string            // user of the client.
 	dbname       string            // default database name.
 	salt         []byte            // random bytes used for authentication.
@@ -147,10 +146,11 @@ type clientConn struct {
 	lastCmd      string            // latest sql query string, currently used for logging error.
 	ctx          QueryCtx          // an interface to execute sql statements.
 	attrs        map[string]string // attributes parsed from client handshake response, not used for now.
-	status       int32             // dispatching/reading/shutdown/waitshutdown
 	peerHost     string            // peer host
 	peerPort     string            // peer port
+	status       int32             // dispatching/reading/shutdown/waitshutdown
 	lastCode     uint16            // last error code
+	collation    uint8             // collation used by client, may be different from the collation used by database.
 }
 
 func (cc *clientConn) String() string {

sessionctx/variable/session.go

@@ -99,22 +99,22 @@ func (r *RetryInfo) GetCurrAutoIncrementID() (int64, error) {
 
 // TransactionContext is used to store variables that has transaction scope.
 type TransactionContext struct {
-	ForUpdate     bool
 	forUpdateTS   uint64
 	DirtyDB       interface{}
 	Binlog        interface{}
 	InfoSchema    interface{}
-	CouldRetry    bool
 	History       interface{}
 	SchemaVersion int64
 	StartTS       uint64
 	Shard         *int64
 	TableDeltaMap map[int64]TableDelta
-	IsPessimistic bool
 
 	// CreateTime For metrics.
 	CreateTime     time.Time
 	StatementCount int
+	ForUpdate      bool
+	CouldRetry     bool
+	IsPessimistic  bool
 }
 
 // UpdateDeltaForTable updates the delta info for some table.

statistics/table.go

@@ -57,18 +57,19 @@ type Table struct {
 // HistColl is a collection of histogram. It collects enough information for plan to calculate the selectivity.
 type HistColl struct {
 	PhysicalID int64
-	// HavePhysicalID is true means this HistColl is from single table and have its ID's information.
-	// The physical id is used when try to load column stats from storage.
-	HavePhysicalID bool
-	Columns        map[int64]*Column
-	Indices        map[int64]*Index
+	Columns    map[int64]*Column
+	Indices    map[int64]*Index
 	// Idx2ColumnIDs maps the index id to its column ids. It's used to calculate the selectivity in planner.
 	Idx2ColumnIDs map[int64][]int64
 	// ColID2IdxID maps the column id to index id whose first column is it. It's used to calculate the selectivity in planner.
 	ColID2IdxID map[int64]int64
-	Pseudo      bool
 	Count       int64
 	ModifyCount int64 // Total modify count in a table.
+
+	// HavePhysicalID is true means this HistColl is from single table and have its ID's information.
+	// The physical id is used when try to load column stats from storage.
+	HavePhysicalID bool
+	Pseudo         bool
 }
 
 // Copy copies the current table.

store/tikv/2pc.go

@@ -89,26 +89,28 @@ type twoPhaseCommitter struct {
 	mutations map[string]*mutationEx
 	lockTTL   uint64
 	commitTS  uint64
-	mu        struct {
-		sync.RWMutex
-		committed       bool
-		undeterminedErr error // undeterminedErr saves the rpc error we encounter when commit primary key.
-	}
-	priority pb.CommandPri
-	syncLog  bool
-	connID   uint64 // connID is used for log.
-	cleanWg  sync.WaitGroup
+	priority  pb.CommandPri
+	connID    uint64 // connID is used for log.
+	cleanWg   sync.WaitGroup
 	// maxTxnTimeUse represents max time a Txn may use (in ms) from its startTS to commitTS.
 	// We use it to guarantee GC worker will not influence any active txn. The value
 	// should be less than GC life time.
 	maxTxnTimeUse uint64
 	detail        *execdetails.CommitDetails
-	// For pessimistic transaction
-	isPessimistic  bool
+
 	primaryKey     []byte
 	forUpdateTS    uint64
-	isFirstLock    bool
 	pessimisticTTL uint64
+
+	mu struct {
+		sync.RWMutex
+		undeterminedErr error // undeterminedErr saves the rpc error we encounter when commit primary key.
+		committed       bool
+	}
+	syncLog bool
+	// For pessimistic transaction
+	isPessimistic bool
+	isFirstLock   bool
 }
 
 type mutationEx struct {

store/tikv/client.go

@@ -199,15 +199,15 @@ func (a *connArray) Close() {
 // that there are too many concurrent requests which overload the service of TiKV.
 type rpcClient struct {
 	sync.RWMutex
-	isClosed bool
-	done     chan struct{}
+	done chan struct{}
 
 	conns    map[string]*connArray
 	security config.Security
 
-	// Implement background cleanup.
-	// Periodically check whether there is any connection that is idle and then close and remove these idle connections.
 	idleNotify uint32
+	// Periodically check whether there is any connection that is idle and then close and remove these idle connections.
+	// Implement background cleanup.
+	isClosed bool
 }
 
 func newRPCClient(security config.Security) *rpcClient {

store/tikv/client_batch.go

@@ -35,7 +35,6 @@ import (
 )
 
 type batchConn struct {
-	index uint32
 	// batchCommandsCh used for batch commands.
 	batchCommandsCh        chan *batchCommandsEntry
 	batchCommandsClients   []*batchCommandsClient
@@ -44,10 +43,12 @@ type batchConn struct {
 
 	// Notify rpcClient to check the idle flag
 	idleNotify *uint32
-	idle       bool
 	idleDetect *time.Timer
 
 	pendingRequests prometheus.Gauge
+
+	index uint32
+	idle  bool
 }
 
 func newBatchConn(connCount, maxBatchSize uint, idleNotify *uint32) *batchConn {

store/tikv/coprocessor.go

@@ -330,10 +330,6 @@ type copIterator struct {
 	req         *kv.Request
 	concurrency int
 	finishCh    chan struct{}
-	// closed represents when the Close is called.
-	// There are two cases we need to close the `finishCh` channel, one is when context is done, the other one is
-	// when the Close is called. we use atomic.CompareAndSwap `closed` to to make sure the channel is not closed twice.
-	closed uint32
 
 	// If keepOrder, results are stored in copTask.respChan, read them out one by one.
 	tasks []*copTask
@@ -344,11 +340,16 @@ type copIterator struct {
 
 	// Otherwise, results are stored in respChan.
 	respChan chan *copResponse
-	wg       sync.WaitGroup
 
 	vars *kv.Variables
 
 	memTracker *memory.Tracker
+
+	wg sync.WaitGroup
+	// closed represents when the Close is called.
+	// There are two cases we need to close the `finishCh` channel, one is when context is done, the other one is
+	// when the Close is called. we use atomic.CompareAndSwap `closed` to to make sure the channel is not closed twice.
+	closed uint32
 }
 
 // copIteratorWorker receives tasks from copIteratorTaskSender, handles tasks and sends the copResponse to respChan.

store/tikv/scan.go

@@ -29,16 +29,17 @@ import (
 type Scanner struct {
 	snapshot     *tikvSnapshot
 	batchSize    int
-	valid        bool
 	cache        []*pb.KvPair
 	idx          int
 	nextStartKey []byte
 	endKey       []byte
-	eof          bool
 
 	// Use for reverse scan.
-	reverse    bool
 	nextEndKey []byte
+	reverse    bool
+
+	valid bool
+	eof   bool
 }
 
 func newScanner(snapshot *tikvSnapshot, startKey []byte, endKey []byte, batchSize int, reverse bool) (*Scanner, error) {

store/tikv/txn.go

@@ -58,11 +58,9 @@ type tikvTxn struct {
 	startTS   uint64
 	startTime time.Time // Monotonic timestamp for recording txn time consuming.
 	commitTS  uint64
-	valid     bool
 	lockKeys  [][]byte
 	lockedMap map[string]struct{}
 	mu        sync.Mutex // For thread-safe LockKeys function.
-	dirty     bool
 	setCnt    int64
 	vars      *kv.Variables
 	committer *twoPhaseCommitter
@@ -73,6 +71,9 @@ type tikvTxn struct {
 	// StmtCommit/StmtRollback may change the confirmed position.
 	assertions []assertionPair
 	confirmed  int
+
+	valid bool
+	dirty bool
 }
 
 func newTiKVTxn(store *tikvStore) (*tikvTxn, error) {

util/filesort/filesort.go

@@ -117,15 +117,11 @@ type FileSorter struct {
 	nWorkers int // number of workers used in async sorting
 	cWorker  int // the next worker to which the sorting job is sent
 
-	mu       sync.Mutex
-	wg       sync.WaitGroup
-	tmpDir   string
-	files    []string
-	nFiles   int
-	closed   bool
-	fetched  bool
-	external bool // mark the necessity of performing external file sort
-	cursor   int  // required when performing full in-memory sort
+	mu     sync.Mutex
+	tmpDir string
+	files  []string
+	nFiles int
+	cursor int // required when performing full in-memory sort
 
 	rowHeap    *rowHeap
 	fds        []*os.File
@@ -135,6 +131,11 @@ type FileSorter struct {
 	keySize    int
 	valSize    int
 	maxRowSize int
+
+	wg       sync.WaitGroup
+	closed   bool
+	fetched  bool
+	external bool // mark the necessity of performing external file sort
 }
 
 // Worker sorts file asynchronously.

util/processinfo.go

@@ -24,22 +24,23 @@ import (
 
 // ProcessInfo is a struct used for show processlist statement.
 type ProcessInfo struct {
-	ID                        uint64
-	User                      string
-	Host                      string
-	DB                        string
-	Command                   byte
-	Plan                      interface{}
-	Time                      time.Time
-	State                     uint16
-	Info                      string
-	CurTxnStartTS             uint64
-	StmtCtx                   *stmtctx.StatementContext
-	StatsInfo                 func(interface{}) map[string]uint64
-	ExceedExpensiveTimeThresh bool
+	ID            uint64
+	User          string
+	Host          string
+	DB            string
+	Plan          interface{}
+	Time          time.Time
+	Info          string
+	CurTxnStartTS uint64
+	StmtCtx       *stmtctx.StatementContext
+	StatsInfo     func(interface{}) map[string]uint64
 	// MaxExecutionTime is the timeout for select statement, in milliseconds.
 	// If the query takes too long, kill it.
 	MaxExecutionTime uint64
+
+	State                     uint16
+	Command                   byte
+	ExceedExpensiveTimeThresh bool
 }
 
 // ToRowForShow returns []interface{} for the row data of "SHOW [FULL] PROCESSLIST".