mydump: set read block buffer size to BlockSize * 5

lightning/config/config.go

@@ -130,7 +130,7 @@ func NewConfig() *Config {
 		App: Lightning{
 			RegionConcurrency: runtime.NumCPU(),
 			TableConcurrency:  8,
-			IOConcurrency:     2,
+			IOConcurrency:     5,
 			CheckRequirements: true,
 		},
 		TiDB: DBStore{

lightning/config/const.go

@@ -9,6 +9,8 @@ const (
 	ReadBlockSize int64 = 64 * _K
 	MinRegionSize int64 = 256 * _M
 
+	BufferSizeScale = 5
+
 	// kv import
 	KVMaxBatchSize int64 = 200 * _G
 )

lightning/metric/metric.go

@@ -106,15 +106,15 @@ var (
 		prometheus.HistogramOpts{
 			Namespace: "lightning",
 			Name:      "chunk_parser_read_block_seconds",
-			Help:      "time needed to chunk parser read a block",
+			Help:      "time needed for chunk parser read a block",
 			Buckets:   prometheus.ExponentialBuckets(0.001, 3.1622776601683795, 10),
 		},
 	)
 	ChunkParserReadRowSecondsHistogram = prometheus.NewHistogram(
 		prometheus.HistogramOpts{
 			Namespace: "lightning",
 			Name:      "chunk_parser_read_row_seconds",
-			Help:      "time needed to chunk parser read a row",
+			Help:      "time needed for chunk parser read a row",
 			Buckets:   prometheus.ExponentialBuckets(0.001, 3.1622776601683795, 10),
 		},
 	)

lightning/mydump/parser.go

@@ -7,6 +7,7 @@ import (
 
 	"github.com/pkg/errors"
 
+	"github.com/pingcap/tidb-lightning/lightning/config"
 	"github.com/pingcap/tidb-lightning/lightning/metric"
 	"github.com/pingcap/tidb-lightning/lightning/worker"
 )
@@ -54,7 +55,7 @@ type Row struct {
 func NewChunkParser(reader io.Reader, blockBufSize int64, ioWorkers *worker.RestoreWorkerPool) *ChunkParser {
 	return &ChunkParser{
 		reader:    reader,
-		blockBuf:  make([]byte, blockBufSize),
+		blockBuf:  make([]byte, blockBufSize*config.BufferSizeScale),
 		remainBuf: &bytes.Buffer{},
 		appendBuf: &bytes.Buffer{},
 		ioWorkers: ioWorkers,
@@ -92,7 +93,7 @@ func (parser *ChunkParser) readBlock() error {
 	// limit IO concurrency
 	w := parser.ioWorkers.Apply()
 	n, err := parser.reader.Read(parser.blockBuf)
-	defer parser.ioWorkers.Recycle(w)
+	parser.ioWorkers.Recycle(w)
 
 	switch err {
 	case io.ErrUnexpectedEOF, io.EOF:

tidb-lightning.toml

@@ -12,9 +12,14 @@ table-concurrency = 8
 # region-concurrency changes the concurrency number of data. It is set to the number of logical CPU cores by default and needs no configuration.
 # In mixed configuration, you can set it to 75% of the size of logical CPU cores.
 # region-concurrency default to runtime.NumCPU()
+
 # region-concurrency =
 # io-concurrency controls the maximum io concurrent
-# io-concurrency = 2
+# Excessive IO concurrency causes an increase in IO latency because the disk
+# internal buffer is frequently refreshed causing a cache miss. For different
+# disk media, concurrency has different effects on IO latency, which can be
+# adjusted according to monitoring.
+# io-concurrency = 5
 
 # logging
 level = "info"