Concurrent CSV parsing and reduce S3 select allocations (#8200)

```
CSV parsing, BEFORE:
BenchmarkReaderBasic-12         	    2842	    407533 ns/op	  397860 B/op	     957 allocs/op
BenchmarkReaderReplace-12       	    2718	    429914 ns/op	  397844 B/op	     957 allocs/op
BenchmarkReaderReplaceTwo-12    	    2718	    435556 ns/op	  397855 B/op	     957 allocs/op
BenchmarkAggregateCount_100K-12    	     171	   6798974 ns/op	16667102 B/op	  308077 allocs/op
BenchmarkAggregateCount_1M-12    	      19	  65657411 ns/op	168057743 B/op	 3146610 allocs/op
BenchmarkSelectAll_10M-12    	       1	20882119900 ns/op	2758799896 B/op	41978762 allocs/op

CSV parsing, AFTER:
BenchmarkReaderBasic-12         	    3721	    312549 ns/op	  101920 B/op	     338 allocs/op
BenchmarkReaderReplace-12       	    3776	    318810 ns/op	  101993 B/op	     340 allocs/op
BenchmarkReaderReplaceTwo-12    	    3610	    330967 ns/op	  102012 B/op	     341 allocs/op
BenchmarkAggregateCount_100K-12    	     295	   4149588 ns/op	 3553623 B/op	  103261 allocs/op
BenchmarkAggregateCount_1M-12    	      30	  37746503 ns/op	33827931 B/op	 1049435 allocs/op
BenchmarkSelectAll_10M-12    	       1	17608495800 ns/op	1416504040 B/op	21007082 allocs/op

~ benchcmp old.txt new.txt
benchmark                           old ns/op       new ns/op       delta
BenchmarkReaderBasic-12             407533          312549          -23.31%
BenchmarkReaderReplace-12           429914          318810          -25.84%
BenchmarkReaderReplaceTwo-12        435556          330967          -24.01%
BenchmarkAggregateCount_100K-12     6798974         4149588         -38.97%
BenchmarkAggregateCount_1M-12       65657411        37746503        -42.51%
BenchmarkSelectAll_10M-12           20882119900     17608495800     -15.68%

benchmark                           old allocs     new allocs     delta
BenchmarkReaderBasic-12             957            338            -64.68%
BenchmarkReaderReplace-12           957            340            -64.47%
BenchmarkReaderReplaceTwo-12        957            341            -64.37%
BenchmarkAggregateCount_100K-12     308077         103261         -66.48%
BenchmarkAggregateCount_1M-12       3146610        1049435        -66.65%
BenchmarkSelectAll_10M-12           41978762       21007082       -49.96%

benchmark                           old bytes      new bytes      delta
BenchmarkReaderBasic-12             397860         101920         -74.38%
BenchmarkReaderReplace-12           397844         101993         -74.36%
BenchmarkReaderReplaceTwo-12        397855         102012         -74.36%
BenchmarkAggregateCount_100K-12     16667102       3553623        -78.68%
BenchmarkAggregateCount_1M-12       168057743      33827931       -79.87%
BenchmarkSelectAll_10M-12           2758799896     1416504040     -48.66%
```

```
BenchmarkReaderHuge/97K-12         	    2200	    540840 ns/op	 184.32 MB/s	 1604450 B/op	     687 allocs/op
BenchmarkReaderHuge/194K-12        	    1522	    752257 ns/op	 265.04 MB/s	 2143135 B/op	    1335 allocs/op
BenchmarkReaderHuge/389K-12        	    1190	    947858 ns/op	 420.69 MB/s	 3221831 B/op	    2630 allocs/op
BenchmarkReaderHuge/778K-12        	     806	   1472486 ns/op	 541.61 MB/s	 5201856 B/op	    5187 allocs/op
BenchmarkReaderHuge/1557K-12       	     426	   2575269 ns/op	 619.36 MB/s	 9101330 B/op	   10233 allocs/op
BenchmarkReaderHuge/3115K-12       	     286	   4034656 ns/op	 790.66 MB/s	12397968 B/op	   16099 allocs/op
BenchmarkReaderHuge/6230K-12       	     172	   6830563 ns/op	 934.05 MB/s	16008416 B/op	   26844 allocs/op
BenchmarkReaderHuge/12461K-12      	     100	  11409467 ns/op	1118.39 MB/s	22655163 B/op	   48107 allocs/op
BenchmarkReaderHuge/24922K-12      	      66	  19780395 ns/op	1290.19 MB/s	35158559 B/op	   90216 allocs/op
BenchmarkReaderHuge/49844K-12      	      34	  37282559 ns/op	1369.03 MB/s	60528624 B/op	  174497 allocs/op
```

docs/select/README.md

@@ -106,3 +106,4 @@ For a more detailed SELECT SQL reference, please see [here](https://docs.aws.ama
 - Large numbers (outside of the signed 64-bit range) are not yet supported.
 - The Date [functions](https://docs.aws.amazon.com/AmazonS3/latest/dev/s3-glacier-select-sql-reference-date.html) `DATE_ADD`, `DATE_DIFF`, `EXTRACT` and `UTCNOW` along with type conversion using `CAST` to the `TIMESTAMP` data type are currently supported.
 - AWS S3's [reserved keywords](https://docs.aws.amazon.com/AmazonS3/latest/dev/s3-glacier-select-sql-reference-keyword-list.html) list is not yet respected.
+- CSV input fields (even quoted) cannot contain newlines even if `RecordDelimiter` is something else.

go.mod

@@ -29,6 +29,7 @@ require (
 	github.com/hashicorp/vault v1.1.0
 	github.com/inconshreveable/go-update v0.0.0-20160112193335-8152e7eb6ccf
 	github.com/json-iterator/go v1.1.7
+	github.com/klauspost/compress v1.5.0
 	github.com/klauspost/pgzip v1.2.1
 	github.com/klauspost/readahead v1.3.0
 	github.com/klauspost/reedsolomon v1.9.1

pkg/s3select/csv/reader.go

@@ -17,89 +17,66 @@
 package csv
 
 import (
+	"bufio"
 	"bytes"
 	"encoding/csv"
 	"fmt"
 	"io"
+	"runtime"
+	"sync"
 
 	"github.com/minio/minio/pkg/s3select/sql"
 )
 
-type recordReader struct {
-	reader          io.Reader
-	recordDelimiter []byte
-	oneByte         []byte
-	useOneByte      bool
-}
-
-func (rr *recordReader) Read(p []byte) (n int, err error) {
-	if rr.useOneByte {
-		p[0] = rr.oneByte[0]
-		rr.useOneByte = false
-		n, err = rr.reader.Read(p[1:])
-		n++
-	} else {
-		n, err = rr.reader.Read(p)
-	}
-
-	if err != nil {
-		return 0, err
-	}
-
-	if string(rr.recordDelimiter) == "\n" {
-		return n, nil
-	}
-
-	for {
-		i := bytes.Index(p, rr.recordDelimiter)
-		if i < 0 {
-			break
-		}
-
-		p[i] = '\n'
-		if len(rr.recordDelimiter) > 1 {
-			p = append(p[:i+1], p[i+len(rr.recordDelimiter):]...)
-			n--
-		}
-	}
-
-	if len(rr.recordDelimiter) == 1 || p[n-1] != rr.recordDelimiter[0] {
-		return n, nil
-	}
-
-	if _, err = rr.reader.Read(rr.oneByte); err != nil {
-		return 0, err
-	}
-
-	if rr.oneByte[0] == rr.recordDelimiter[1] {
-		p[n-1] = '\n'
-		return n, nil
-	}
-
-	rr.useOneByte = true
-	return n, nil
-}
-
 // Reader - CSV record reader for S3Select.
 type Reader struct {
 	args         *ReaderArgs
-	readCloser   io.ReadCloser
-	csvReader    *csv.Reader
-	columnNames  []string
-	nameIndexMap map[string]int64
+	readCloser   io.ReadCloser    // raw input
+	buf          *bufio.Reader    // input to the splitter
+	columnNames  []string         // names of columns
+	nameIndexMap map[string]int64 // name to column index
+	current      [][]string       // current block of results to be returned
+	recordsRead  int              // number of records read in current slice
+	input        chan *queueItem  // input for workers
+	queue        chan *queueItem  // output from workers in order
+	err          error            // global error state, only touched by Reader.Read
+	bufferPool   sync.Pool        // pool of []byte objects for input
+	csvDstPool   sync.Pool        // pool of [][]string used for output
+	close        chan struct{}    // used for shutting down the splitter before end of stream
+	readerWg     sync.WaitGroup   // used to keep track of async reader.
+}
+
+// queueItem is an item in the queue.
+type queueItem struct {
+	input []byte          // raw input sent to the worker
+	dst   chan [][]string // result of block decode
+	err   error           // any error encountered will be set here
 }
 
 // Read - reads single record.
-func (r *Reader) Read() (sql.Record, error) {
-	csvRecord, err := r.csvReader.Read()
-	if err != nil {
-		if err != io.EOF {
-			return nil, errCSVParsingError(err)
+// Once Read is called the previous record should no longer be referenced.
+func (r *Reader) Read(dst sql.Record) (sql.Record, error) {
+	// If we have have any records left, return these before any error.
+	for len(r.current) <= r.recordsRead {
+		if r.err != nil {
+			return nil, r.err
 		}
-
-		return nil, err
+		// Move to next block
+		item, ok := <-r.queue
+		if !ok {
+			r.err = io.EOF
+			return nil, r.err
+		}
+		//lint:ignore SA6002 Using pointer would allocate more since we would have to copy slice header before taking a pointer.
+		r.csvDstPool.Put(r.current)
+		r.current = <-item.dst
+		r.err = item.err
+		r.recordsRead = 0
 	}
+	csvRecord := r.current[r.recordsRead]
+	r.recordsRead++
 
+	// If no column names are set, use _(index)
 	if r.columnNames == nil {
 		r.columnNames = make([]string, len(csvRecord))
 		for i := range csvRecord {
@@ -107,67 +84,225 @@ func (r *Reader) Read() (sql.Record, error) {
 		}
 	}
 
+	// If no index max, add that.
 	if r.nameIndexMap == nil {
 		r.nameIndexMap = make(map[string]int64)
 		for i := range r.columnNames {
 			r.nameIndexMap[r.columnNames[i]] = int64(i)
 		}
 	}
+	dstRec, ok := dst.(*Record)
+	if !ok {
+		dstRec = &Record{}
+	}
+	dstRec.columnNames = r.columnNames
+	dstRec.csvRecord = csvRecord
+	dstRec.nameIndexMap = r.nameIndexMap
 
-	return &Record{
-		columnNames:  r.columnNames,
-		csvRecord:    csvRecord,
-		nameIndexMap: r.nameIndexMap,
-	}, nil
+	return dstRec, nil
 }
 
-// Close - closes underlaying reader.
+// Close - closes underlying reader.
 func (r *Reader) Close() error {
+	if r.close != nil {
+		close(r.close)
+		r.close = nil
+		r.readerWg.Wait()
+	}
+	r.recordsRead = len(r.current)
+	if r.err == nil {
+		r.err = io.EOF
+	}
 	return r.readCloser.Close()
 }
 
-// NewReader - creates new CSV reader using readCloser.
-func NewReader(readCloser io.ReadCloser, args *ReaderArgs) (*Reader, error) {
-	if args == nil || args.IsEmpty() {
-		panic(fmt.Errorf("empty args passed %v", args))
+// nextSplit will attempt to skip a number of bytes and
+// return the buffer until the next newline occurs.
+// The last block will be sent along with an io.EOF.
+func (r *Reader) nextSplit(skip int, dst []byte) ([]byte, error) {
+	if cap(dst) < skip {
+		dst = make([]byte, 0, skip+1024)
+	}
+	dst = dst[:skip]
+	if skip > 0 {
+		n, err := io.ReadFull(r.buf, dst)
+		if err != nil && err != io.ErrUnexpectedEOF {
+			// If an EOF happens after reading some but not all the bytes,
+			// ReadFull returns ErrUnexpectedEOF.
+			return dst[:n], err
+		}
+		dst = dst[:n]
+		if err == io.ErrUnexpectedEOF {
+			return dst, io.EOF
+		}
 	}
+	// Read until next line.
+	in, err := r.buf.ReadBytes('\n')
+	dst = append(dst, in...)
+	return dst, err
+}
 
-	csvReader := csv.NewReader(&recordReader{
-		reader:          readCloser,
-		recordDelimiter: []byte(args.RecordDelimiter),
-		oneByte:         []byte{0},
-	})
-	csvReader.Comma = []rune(args.FieldDelimiter)[0]
-	csvReader.Comment = []rune(args.CommentCharacter)[0]
-	csvReader.FieldsPerRecord = -1
-	// If LazyQuotes is true, a quote may appear in an unquoted field and a
-	// non-doubled quote may appear in a quoted field.
-	csvReader.LazyQuotes = true
-	// We do not trim leading space to keep consistent with s3.
-	csvReader.TrimLeadingSpace = false
+// csvSplitSize is the size of each block.
+// Blocks will read this much and find the first following newline.
+// 128KB appears to be a very reasonable default.
+const csvSplitSize = 128 << 10
 
-	r := &Reader{
-		args:       args,
-		readCloser: readCloser,
-		csvReader:  csvReader,
+// startReaders will read the header if needed and spin up a parser
+// and a number of workers based on GOMAXPROCS.
+// If an error is returned no goroutines have been started and r.err will have been set.
+func (r *Reader) startReaders(in io.Reader, newReader func(io.Reader) *csv.Reader) error {
+	if r.args.FileHeaderInfo != none {
+		// Read column names
+		// Get one line.
+		b, err := r.nextSplit(0, nil)
+		if err != nil {
+			r.err = err
+			return err
+		}
+		reader := newReader(bytes.NewReader(b))
+		record, err := reader.Read()
+		if err != nil {
+			r.err = err
+			if err != io.EOF {
+				r.err = errCSVParsingError(err)
+				return errCSVParsingError(err)
+			}
+			return err
+		}
+
+		if r.args.FileHeaderInfo == use {
+			// Copy column names since records will be reused.
+			columns := append(make([]string, 0, len(record)), record...)
+			r.columnNames = columns
+		}
 	}
 
-	if args.FileHeaderInfo == none {
-		return r, nil
+	r.bufferPool.New = func() interface{} {
+		return make([]byte, csvSplitSize+1024)
+	}
+
+	// Create queue
+	r.queue = make(chan *queueItem, runtime.GOMAXPROCS(0))
+	r.input = make(chan *queueItem, runtime.GOMAXPROCS(0))
+	r.readerWg.Add(1)
+
+	// Start splitter
+	go func() {
+		defer close(r.input)
+		defer close(r.queue)
+		defer r.readerWg.Done()
+		for {
+			next, err := r.nextSplit(csvSplitSize, r.bufferPool.Get().([]byte))
+			q := queueItem{
+				input: next,
+				dst:   make(chan [][]string, 1),
+				err:   err,
+			}
+			select {
+			case <-r.close:
+				return
+			case r.queue <- &q:
+			}
+
+			select {
+			case <-r.close:
+				return
+			case r.input <- &q:
+			}
+			if err != nil {
+				// Exit on any error.
+				return
+			}
+		}
+	}()
+
+	// Start parsers
+	for i := 0; i < runtime.GOMAXPROCS(0); i++ {
+		go func() {
+			for in := range r.input {
+				if len(in.input) == 0 {
+					in.dst <- nil
+					continue
+				}
+				dst, ok := r.csvDstPool.Get().([][]string)
+				if !ok {
+					dst = make([][]string, 0, 1000)
+				}
+
+				cr := newReader(bytes.NewBuffer(in.input))
+				all := dst[:0]
+				err := func() error {
+					// Read all records until EOF or another error.
+					for {
+						record, err := cr.Read()
+						if err == io.EOF {
+							return nil
+						}
+						if err != nil {
+							return errCSVParsingError(err)
+						}
+						var recDst []string
+						if len(dst) > len(all) {
+							recDst = dst[len(all)]
+						}
+						if cap(recDst) < len(record) {
+							recDst = make([]string, len(record))
+						}
+						recDst = recDst[:len(record)]
+						copy(recDst, record)
+						all = append(all, recDst)
+					}
+				}()
+				if err != nil {
+					in.err = err
+				}
+				// We don't need the input any more.
+				//lint:ignore SA6002 Using pointer would allocate more since we would have to copy slice header before taking a pointer.
+				r.bufferPool.Put(in.input)
+				in.input = nil
+				in.dst <- all
+			}
+		}()
 	}
+	return nil
 
-	record, err := csvReader.Read()
-	if err != nil {
-		if err != io.EOF {
-			return nil, errCSVParsingError(err)
+}
+
+// NewReader - creates new CSV reader using readCloser.
+func NewReader(readCloser io.ReadCloser, args *ReaderArgs) (*Reader, error) {
+	if args == nil || args.IsEmpty() {
+		panic(fmt.Errorf("empty args passed %v", args))
+	}
+	csvIn := io.Reader(readCloser)
+	if args.RecordDelimiter != "\n" {
+		csvIn = &recordTransform{
+			reader:          readCloser,
+			recordDelimiter: []byte(args.RecordDelimiter),
+			oneByte:         make([]byte, len(args.RecordDelimiter)-1),
 		}
+	}
 
-		return nil, err
+	r := &Reader{
+		args:       args,
+		buf:        bufio.NewReaderSize(csvIn, csvSplitSize*2),
+		readCloser: readCloser,
+		close:      make(chan struct{}),
 	}
 
-	if args.FileHeaderInfo == use {
-		r.columnNames = record
+	// Assume args are validated by ReaderArgs.UnmarshalXML()
+	newCsvReader := func(r io.Reader) *csv.Reader {
+		ret := csv.NewReader(r)
+		ret.Comma = []rune(args.FieldDelimiter)[0]
+		ret.Comment = []rune(args.CommentCharacter)[0]
+		ret.FieldsPerRecord = -1
+		// If LazyQuotes is true, a quote may appear in an unquoted field and a
+		// non-doubled quote may appear in a quoted field.
+		ret.LazyQuotes = true
+		// We do not trim leading space to keep consistent with s3.
+		ret.TrimLeadingSpace = false
+		ret.ReuseRecord = true
+		return ret
 	}
 
-	return r, nil
+	return r, r.startReaders(csvIn, newCsvReader)
 }

pkg/s3select/csv/reader_test.go

@@ -18,11 +18,16 @@ package csv
 
 import (
 	"bytes"
+	"errors"
+	"fmt"
 	"io"
 	"io/ioutil"
+	"path/filepath"
+	"reflect"
 	"strings"
 	"testing"
 
+	"github.com/klauspost/compress/zip"
 	"github.com/minio/minio/pkg/s3select/sql"
 )
 
@@ -49,12 +54,12 @@ func TestRead(t *testing.T) {
 			QuoteCharacter:             defaultQuoteCharacter,
 			QuoteEscapeCharacter:       defaultQuoteEscapeCharacter,
 			CommentCharacter:           defaultCommentCharacter,
-			AllowQuotedRecordDelimiter: true,
+			AllowQuotedRecordDelimiter: false,
 			unmarshaled:                true,
 		})
 
 		for {
-			record, err = r.Read()
+			record, err = r.Read(record)
 			if err != nil {
 				break
 			}
@@ -72,3 +77,555 @@ func TestRead(t *testing.T) {
 		}
 	}
 }
+
+type tester interface {
+	Fatal(...interface{})
+}
+
+func openTestFile(t tester, file string) []byte {
+	f, err := ioutil.ReadFile(filepath.Join("testdata/testdata.zip"))
+	if err != nil {
+		t.Fatal(err)
+	}
+	z, err := zip.NewReader(bytes.NewReader(f), int64(len(f)))
+	if err != nil {
+		t.Fatal(err)
+	}
+	for _, f := range z.File {
+		if f.Name == file {
+			rc, err := f.Open()
+			if err != nil {
+				t.Fatal(err)
+			}
+			defer rc.Close()
+			b, err := ioutil.ReadAll(rc)
+			if err != nil {
+				t.Fatal(err)
+			}
+			return b
+		}
+	}
+	t.Fatal(file, "not found in testdata/testdata.zip")
+	return nil
+}
+
+func TestReadExtended(t *testing.T) {
+	cases := []struct {
+		file            string
+		recordDelimiter string
+		fieldDelimiter  string
+		header          bool
+		wantColumns     []string
+		wantTenFields   string
+		totalFields     int
+	}{
+		{
+			file:            "nyc-taxi-data-100k.csv",
+			recordDelimiter: "\n",
+			fieldDelimiter:  ",",
+			header:          true,
+			wantColumns:     []string{"trip_id", "vendor_id", "pickup_datetime", "dropoff_datetime", "store_and_fwd_flag", "rate_code_id", "pickup_longitude", "pickup_latitude", "dropoff_longitude", "dropoff_latitude", "passenger_count", "trip_distance", "fare_amount", "extra", "mta_tax", "tip_amount", "tolls_amount", "ehail_fee", "improvement_surcharge", "total_amount", "payment_type", "trip_type", "pickup", "dropoff", "cab_type", "precipitation", "snow_depth", "snowfall", "max_temp", "min_temp", "wind", "pickup_nyct2010_gid", "pickup_ctlabel", "pickup_borocode", "pickup_boroname", "pickup_ct2010", "pickup_boroct2010", "pickup_cdeligibil", "pickup_ntacode", "pickup_ntaname", "pickup_puma", "dropoff_nyct2010_gid", "dropoff_ctlabel", "dropoff_borocode", "dropoff_boroname", "dropoff_ct2010", "dropoff_boroct2010", "dropoff_cdeligibil", "dropoff_ntacode", "dropoff_ntaname", "dropoff_puma"},
+			wantTenFields: `3389224,2,2014-03-26 00:26:15,2014-03-26 00:28:38,N,1,-73.950431823730469,40.792251586914063,-73.938949584960937,40.794425964355469,1,0.84,4.5,0.5,0.5,1,0,,,6.5,1,1,75,74,green,0.00,0.0,0.0,36,24,11.86,1267,168,1,Manhattan,016800,1016800,E,MN33,East Harlem South,3804,1828,180,1,Manhattan,018000,1018000,E,MN34,East Harlem North,3804
+3389225,2,2014-03-31 09:42:15,2014-03-31 10:01:17,N,1,-73.950340270996094,40.792228698730469,-73.941970825195313,40.842235565185547,1,4.47,17.5,0,0.5,0,0,,,18,2,1,75,244,green,0.16,0.0,0.0,56,36,8.28,1267,168,1,Manhattan,016800,1016800,E,MN33,East Harlem South,3804,911,251,1,Manhattan,025100,1025100,E,MN36,Washington Heights South,3801
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+3389228,1,2014-03-28 13:52:56,2014-03-28 14:29:01,N,1,-73.950569152832031,40.792312622070313,-73.868507385253906,40.688491821289063,2,16.10,46,0,0.5,0,5.33,,,51.83,2,,75,63,green,0.04,0.0,0.0,62,37,5.37,1267,168,1,Manhattan,016800,1016800,E,MN33,East Harlem South,3804,1544,1182.02,3,Brooklyn,118202,3118202,E,BK83,Cypress Hills-City Line,4008
+3389229,2,2014-03-07 09:46:32,2014-03-07 09:55:01,N,1,-73.952301025390625,40.789798736572266,-73.935806274414062,40.794448852539063,1,1.67,8,0,0.5,2,0,,,10.5,1,1,75,74,green,0.00,3.9,0.0,37,26,7.83,1267,168,1,Manhattan,016800,1016800,E,MN33,East Harlem South,3804,1553,178,1,Manhattan,017800,1017800,E,MN34,East Harlem North,3804
+3389230,2,2014-03-17 18:23:05,2014-03-17 18:28:38,N,1,-73.952346801757813,40.789844512939453,-73.946319580078125,40.783851623535156,5,0.95,5.5,1,0.5,0.65,0,,,7.65,1,1,75,263,green,0.00,0.0,0.0,35,23,8.05,1267,168,1,Manhattan,016800,1016800,E,MN33,East Harlem South,3804,32,156.01,1,Manhattan,015601,1015601,I,MN32,Yorkville,3805
+3389231,1,2014-03-19 19:09:36,2014-03-19 19:12:20,N,1,-73.952377319335938,40.789779663085938,-73.947494506835938,40.796474456787109,1,0.50,4,1,0.5,1,0,,,6.5,1,,75,75,green,0.92,0.0,0.0,46,32,7.16,1267,168,1,Manhattan,016800,1016800,E,MN33,East Harlem South,3804,1401,174.02,1,Manhattan,017402,1017402,E,MN33,East Harlem South,3804
+3389232,2,2014-03-20 19:06:28,2014-03-20 19:21:35,N,1,-73.952583312988281,40.789516448974609,-73.985870361328125,40.776973724365234,2,3.04,13,1,0.5,2.8,0,,,17.3,1,1,75,143,green,0.00,0.0,0.0,54,40,8.05,1267,168,1,Manhattan,016800,1016800,E,MN33,East Harlem South,3804,1742,155,1,Manhattan,015500,1015500,I,MN14,Lincoln Square,3806
+3389233,2,2014-03-29 09:38:12,2014-03-29 09:44:16,N,1,-73.952728271484375,40.789501190185547,-73.950935363769531,40.775600433349609,1,1.10,6.5,0,0.5,1.3,0,,,8.3,1,1,75,263,green,1.81,0.0,0.0,59,43,10.74,1267,168,1,Manhattan,016800,1016800,E,MN33,East Harlem South,3804,2048,138,1,Manhattan,013800,1013800,I,MN32,Yorkville,3805
+`,
+			totalFields: 308*2 + 1,
+		}, {
+			file:            "nyc-taxi-data-noheader-100k.csv",
+			recordDelimiter: "\n",
+			fieldDelimiter:  ",",
+			header:          false,
+			wantColumns:     []string{"_1", "_2", "_3", "_4", "_5", "_6", "_7", "_8", "_9", "_10", "_11", "_12", "_13", "_14", "_15", "_16", "_17", "_18", "_19", "_20", "_21", "_22", "_23", "_24", "_25", "_26", "_27", "_28", "_29", "_30", "_31", "_32", "_33", "_34", "_35", "_36", "_37", "_38", "_39", "_40", "_41", "_42", "_43", "_44", "_45", "_46", "_47", "_48", "_49", "_50", "_51"},
+			wantTenFields: `3389224,2,2014-03-26 00:26:15,2014-03-26 00:28:38,N,1,-73.950431823730469,40.792251586914063,-73.938949584960937,40.794425964355469,1,0.84,4.5,0.5,0.5,1,0,,,6.5,1,1,75,74,green,0.00,0.0,0.0,36,24,11.86,1267,168,1,Manhattan,016800,1016800,E,MN33,East Harlem South,3804,1828,180,1,Manhattan,018000,1018000,E,MN34,East Harlem North,3804
+3389225,2,2014-03-31 09:42:15,2014-03-31 10:01:17,N,1,-73.950340270996094,40.792228698730469,-73.941970825195313,40.842235565185547,1,4.47,17.5,0,0.5,0,0,,,18,2,1,75,244,green,0.16,0.0,0.0,56,36,8.28,1267,168,1,Manhattan,016800,1016800,E,MN33,East Harlem South,3804,911,251,1,Manhattan,025100,1025100,E,MN36,Washington Heights South,3801
+3389226,2,2014-03-26 17:13:28,2014-03-26 17:19:07,N,1,-73.949493408203125,40.793506622314453,-73.943374633789063,40.786155700683594,1,0.82,5.5,1,0.5,0,0,,,7,1,1,75,75,green,0.00,0.0,0.0,36,24,11.86,1267,168,1,Manhattan,016800,1016800,E,MN33,East Harlem South,3804,1387,164,1,Manhattan,016400,1016400,E,MN33,East Harlem South,3804
+3389227,2,2014-03-14 21:07:19,2014-03-14 21:11:41,N,1,-73.950538635253906,40.792228698730469,-73.940811157226563,40.809253692626953,1,1.40,6,0.5,0.5,0,0,,,7,2,1,75,42,green,0.00,0.0,0.0,46,22,5.59,1267,168,1,Manhattan,016800,1016800,E,MN33,East Harlem South,3804,1184,208,1,Manhattan,020800,1020800,E,MN03,Central Harlem North-Polo Grounds,3803
+3389228,1,2014-03-28 13:52:56,2014-03-28 14:29:01,N,1,-73.950569152832031,40.792312622070313,-73.868507385253906,40.688491821289063,2,16.10,46,0,0.5,0,5.33,,,51.83,2,,75,63,green,0.04,0.0,0.0,62,37,5.37,1267,168,1,Manhattan,016800,1016800,E,MN33,East Harlem South,3804,1544,1182.02,3,Brooklyn,118202,3118202,E,BK83,Cypress Hills-City Line,4008
+3389229,2,2014-03-07 09:46:32,2014-03-07 09:55:01,N,1,-73.952301025390625,40.789798736572266,-73.935806274414062,40.794448852539063,1,1.67,8,0,0.5,2,0,,,10.5,1,1,75,74,green,0.00,3.9,0.0,37,26,7.83,1267,168,1,Manhattan,016800,1016800,E,MN33,East Harlem South,3804,1553,178,1,Manhattan,017800,1017800,E,MN34,East Harlem North,3804
+3389230,2,2014-03-17 18:23:05,2014-03-17 18:28:38,N,1,-73.952346801757813,40.789844512939453,-73.946319580078125,40.783851623535156,5,0.95,5.5,1,0.5,0.65,0,,,7.65,1,1,75,263,green,0.00,0.0,0.0,35,23,8.05,1267,168,1,Manhattan,016800,1016800,E,MN33,East Harlem South,3804,32,156.01,1,Manhattan,015601,1015601,I,MN32,Yorkville,3805
+3389231,1,2014-03-19 19:09:36,2014-03-19 19:12:20,N,1,-73.952377319335938,40.789779663085938,-73.947494506835938,40.796474456787109,1,0.50,4,1,0.5,1,0,,,6.5,1,,75,75,green,0.92,0.0,0.0,46,32,7.16,1267,168,1,Manhattan,016800,1016800,E,MN33,East Harlem South,3804,1401,174.02,1,Manhattan,017402,1017402,E,MN33,East Harlem South,3804
+3389232,2,2014-03-20 19:06:28,2014-03-20 19:21:35,N,1,-73.952583312988281,40.789516448974609,-73.985870361328125,40.776973724365234,2,3.04,13,1,0.5,2.8,0,,,17.3,1,1,75,143,green,0.00,0.0,0.0,54,40,8.05,1267,168,1,Manhattan,016800,1016800,E,MN33,East Harlem South,3804,1742,155,1,Manhattan,015500,1015500,I,MN14,Lincoln Square,3806
+3389233,2,2014-03-29 09:38:12,2014-03-29 09:44:16,N,1,-73.952728271484375,40.789501190185547,-73.950935363769531,40.775600433349609,1,1.10,6.5,0,0.5,1.3,0,,,8.3,1,1,75,263,green,1.81,0.0,0.0,59,43,10.74,1267,168,1,Manhattan,016800,1016800,E,MN33,East Harlem South,3804,2048,138,1,Manhattan,013800,1013800,I,MN32,Yorkville,3805
+`,
+			totalFields: 308 * 2,
+		},
+	}
+
+	for i, c := range cases {
+		t.Run(c.file, func(t *testing.T) {
+
+			var err error
+			var record sql.Record
+			var result bytes.Buffer
+			input := openTestFile(t, c.file)
+			// Get above block size.
+			input = append(input, input...)
+			args := ReaderArgs{
+				FileHeaderInfo:             use,
+				RecordDelimiter:            c.recordDelimiter,
+				FieldDelimiter:             c.fieldDelimiter,
+				QuoteCharacter:             defaultQuoteCharacter,
+				QuoteEscapeCharacter:       defaultQuoteEscapeCharacter,
+				CommentCharacter:           defaultCommentCharacter,
+				AllowQuotedRecordDelimiter: false,
+				unmarshaled:                true,
+			}
+			if !c.header {
+				args.FileHeaderInfo = none
+			}
+			r, _ := NewReader(ioutil.NopCloser(bytes.NewReader(input)), &args)
+			fields := 0
+			for {
+				record, err = r.Read(record)
+				if err != nil {
+					break
+				}
+				if fields < 10 {
+					// Write with fixed delimiters, newlines.
+					err := record.WriteCSV(&result, ',')
+					if err != nil {
+						t.Error(err)
+					}
+				}
+				fields++
+			}
+			r.Close()
+			if err != io.EOF {
+				t.Fatalf("Case %d failed with %s", i, err)
+			}
+			if !reflect.DeepEqual(r.columnNames, c.wantColumns) {
+				t.Errorf("Case %d failed: expected %#v, got result %#v", i, c.wantColumns, r.columnNames)
+			}
+			if result.String() != c.wantTenFields {
+				t.Errorf("Case %d failed: expected %v, got result %v", i, c.wantTenFields, result.String())
+			}
+			if fields != c.totalFields {
+				t.Errorf("Case %d failed: expected %v results %v", i, c.totalFields, fields)
+			}
+		})
+	}
+}
+
+type errReader struct {
+	err error
+}
+
+func (e errReader) Read(p []byte) (n int, err error) {
+	return 0, e.err
+}
+
+func TestReadFailures(t *testing.T) {
+	customErr := errors.New("unable to read file :(")
+	cases := []struct {
+		file            string
+		recordDelimiter string
+		fieldDelimiter  string
+		sendErr         error
+		header          bool
+		wantColumns     []string
+		wantFields      string
+		wantErr         error
+	}{
+		{
+			file:            "truncated-records.csv",
+			recordDelimiter: "^Y",
+			fieldDelimiter:  ",",
+			header:          true,
+			wantColumns:     []string{"trip_id", "vendor_id", "pickup_datetime", "dropoff_datetime", "store_and_fwd_flag", "rate_code_id", "pickup_longitude", "pickup_latitude", "dropoff_longitude", "dropoff_latitude", "passenger_count", "trip_distance", "fare_amount", "extra", "mta_tax", "tip_amount", "tolls_amount", "ehail_fee", "improvement_surcharge", "total_amount", "payment_type", "trip_type", "pickup", "dropoff", "cab_type", "precipitation", "snow_depth", "snowfall", "max_temp", "min_temp", "wind", "pickup_nyct2010_gid", "pickup_ctlabel", "pickup_borocode", "pickup_boroname", "pickup_ct2010", "pickup_boroct2010", "pickup_cdeligibil", "pickup_ntacode", "pickup_ntaname", "pickup_puma", "dropoff_nyct2010_gid", "dropoff_ctlabel", "dropoff_borocode", "dropoff_boroname", "dropoff_ct2010", "dropoff_boroct2010", "dropoff_cdeligibil", "dropoff_ntacode", "dropoff_ntaname", "dropoff_puma"},
+			wantFields: `3389224,2,2014-03-26 00:26:15,2014-03-26 00:28:38,N,1,-73.950431823730469,40.792251586914063,-73.938949584960937,40.794425964355469,1,0.84,4.5,0.5,0.5,1,0,,,6.5,1,1,75,74,green,0.00,0.0,0.0,36,24,11.86,1267,168,1,Manhattan,016800,1016800,E,MN33,East Harlem South,3804,1828,180,1,Manhattan,018000,1018000,E,MN34,East Harlem North,3804
+3389225,2,2014-03-31 09:42:15,2014-03-31 10:01:17,N,1,-73.950340270996094,40.792228698730469,-73.941970825195313,40.842235565185547,1,4.47,17.5,0,0.5,0,0,,,18,2,1,75,244,green,0.16,0.0,0.0,56,36,8.28,1267,168,1,Manhattan,016800,1016800,E,MN33,East Harlem South,3804,911,251,1,Manhattan,025100
+`,
+			wantErr: io.EOF,
+		},
+		{
+			file:            "truncated-records.csv",
+			recordDelimiter: "^Y",
+			fieldDelimiter:  ",",
+			sendErr:         customErr,
+			header:          true,
+			wantColumns:     []string{"trip_id", "vendor_id", "pickup_datetime", "dropoff_datetime", "store_and_fwd_flag", "rate_code_id", "pickup_longitude", "pickup_latitude", "dropoff_longitude", "dropoff_latitude", "passenger_count", "trip_distance", "fare_amount", "extra", "mta_tax", "tip_amount", "tolls_amount", "ehail_fee", "improvement_surcharge", "total_amount", "payment_type", "trip_type", "pickup", "dropoff", "cab_type", "precipitation", "snow_depth", "snowfall", "max_temp", "min_temp", "wind", "pickup_nyct2010_gid", "pickup_ctlabel", "pickup_borocode", "pickup_boroname", "pickup_ct2010", "pickup_boroct2010", "pickup_cdeligibil", "pickup_ntacode", "pickup_ntaname", "pickup_puma", "dropoff_nyct2010_gid", "dropoff_ctlabel", "dropoff_borocode", "dropoff_boroname", "dropoff_ct2010", "dropoff_boroct2010", "dropoff_cdeligibil", "dropoff_ntacode", "dropoff_ntaname", "dropoff_puma"},
+			wantFields: `3389224,2,2014-03-26 00:26:15,2014-03-26 00:28:38,N,1,-73.950431823730469,40.792251586914063,-73.938949584960937,40.794425964355469,1,0.84,4.5,0.5,0.5,1,0,,,6.5,1,1,75,74,green,0.00,0.0,0.0,36,24,11.86,1267,168,1,Manhattan,016800,1016800,E,MN33,East Harlem South,3804,1828,180,1,Manhattan,018000,1018000,E,MN34,East Harlem North,3804
+3389225,2,2014-03-31 09:42:15,2014-03-31 10:01:17,N,1,-73.950340270996094,40.792228698730469,-73.941970825195313,40.842235565185547,1,4.47,17.5,0,0.5,0,0,,,18,2,1,75,244,green,0.16,0.0,0.0,56,36,8.28,1267,168,1,Manhattan,016800,1016800,E,MN33,East Harlem South,3804,911,251,1,Manhattan,025100
+`,
+			wantErr: customErr,
+		},
+		{
+			// This works since LazyQuotes is true:
+			file:            "invalid-badbarequote.csv",
+			recordDelimiter: "\n",
+			fieldDelimiter:  ",",
+			sendErr:         nil,
+			header:          true,
+			wantColumns:     []string{"header1", "header2", "header3"},
+			wantFields:      "ok1,ok2,ok3\n" + `"a ""word""",b` + "\n",
+			wantErr:         io.EOF,
+		},
+		{
+			// This works since LazyQuotes is true:
+			file:            "invalid-baddoubleq.csv",
+			recordDelimiter: "\n",
+			fieldDelimiter:  ",",
+			sendErr:         nil,
+			header:          true,
+			wantColumns:     []string{"header1", "header2", "header3"},
+			wantFields:      "ok1,ok2,ok3\n" + `"a""""b",c` + "\n",
+			wantErr:         io.EOF,
+		},
+		{
+			// This works since LazyQuotes is true:
+			file:            "invalid-badextraq.csv",
+			recordDelimiter: "\n",
+			fieldDelimiter:  ",",
+			sendErr:         nil,
+			header:          true,
+			wantColumns:     []string{"header1", "header2", "header3"},
+			wantFields:      "ok1,ok2,ok3\n" + `a word,"b"""` + "\n",
+			wantErr:         io.EOF,
+		},
+		{
+			// This works since LazyQuotes is true:
+			file:            "invalid-badstartline.csv",
+			recordDelimiter: "\n",
+			fieldDelimiter:  ",",
+			sendErr:         nil,
+			header:          true,
+			wantColumns:     []string{"header1", "header2", "header3"},
+			wantFields:      "ok1,ok2,ok3\n" + `a,"b` + "\n" + `c""d,e` + "\n\"\n",
+			wantErr:         io.EOF,
+		},
+		{
+			// This works since LazyQuotes is true:
+			file:            "invalid-badstartline2.csv",
+			recordDelimiter: "\n",
+			fieldDelimiter:  ",",
+			sendErr:         nil,
+			header:          true,
+			wantColumns:     []string{"header1", "header2", "header3"},
+			wantFields:      "ok1,ok2,ok3\n" + `a,b` + "\n" + `"d` + "\n\ne\"\n",
+			wantErr:         io.EOF,
+		},
+		{
+			// This works since LazyQuotes is true:
+			file:            "invalid-badtrailingq.csv",
+			recordDelimiter: "\n",
+			fieldDelimiter:  ",",
+			sendErr:         nil,
+			header:          true,
+			wantColumns:     []string{"header1", "header2", "header3"},
+			wantFields:      "ok1,ok2,ok3\n" + `a word,"b"""` + "\n",
+			wantErr:         io.EOF,
+		},
+		{
+			// This works since LazyQuotes is true:
+			file:            "invalid-crlfquoted.csv",
+			recordDelimiter: "\n",
+			fieldDelimiter:  ",",
+			sendErr:         nil,
+			header:          true,
+			wantColumns:     []string{"header1", "header2", "header3"},
+			wantFields:      "ok1,ok2,ok3\n" + `"foo""bar"` + "\n",
+			wantErr:         io.EOF,
+		},
+		{
+			// This works since LazyQuotes is true:
+			file:            "invalid-csv.csv",
+			recordDelimiter: "\n",
+			fieldDelimiter:  ",",
+			sendErr:         nil,
+			header:          true,
+			wantColumns:     []string{"header1", "header2", "header3"},
+			wantFields:      "ok1,ok2,ok3\n" + `"a""""b",c` + "\n",
+			wantErr:         io.EOF,
+		},
+		{
+			// This works since LazyQuotes is true, but output is very weird.
+			file:            "invalid-oddquote.csv",
+			recordDelimiter: "\n",
+			fieldDelimiter:  ",",
+			sendErr:         nil,
+			header:          true,
+			wantColumns:     []string{"header1", "header2", "header3"},
+			wantFields:      "ok1,ok2,ok3\n" + `""""""",b,c` + "\n\"\n",
+			wantErr:         io.EOF,
+		},
+		{
+			// Test when file ends with a half separator
+			file:            "endswithhalfsep.csv",
+			recordDelimiter: "%!",
+			fieldDelimiter:  ",",
+			sendErr:         nil,
+			header:          false,
+			wantColumns:     []string{"_1", "_2", "_3"},
+			wantFields:      "a,b,c\na2,b2,c2%\n",
+			wantErr:         io.EOF,
+		},
+	}
+
+	for i, c := range cases {
+		t.Run(c.file, func(t *testing.T) {
+
+			var err error
+			var record sql.Record
+			var result bytes.Buffer
+			input := openTestFile(t, c.file)
+			args := ReaderArgs{
+				FileHeaderInfo:             use,
+				RecordDelimiter:            c.recordDelimiter,
+				FieldDelimiter:             c.fieldDelimiter,
+				QuoteCharacter:             defaultQuoteCharacter,
+				QuoteEscapeCharacter:       defaultQuoteEscapeCharacter,
+				CommentCharacter:           defaultCommentCharacter,
+				AllowQuotedRecordDelimiter: false,
+				unmarshaled:                true,
+			}
+			if !c.header {
+				args.FileHeaderInfo = none
+			}
+			inr := io.Reader(bytes.NewReader(input))
+			if c.sendErr != nil {
+				inr = io.MultiReader(inr, errReader{c.sendErr})
+			}
+			r, _ := NewReader(ioutil.NopCloser(inr), &args)
+			fields := 0
+			for {
+				record, err = r.Read(record)
+				if err != nil {
+					break
+				}
+				// Write with fixed delimiters, newlines.
+				err := record.WriteCSV(&result, ',')
+				if err != nil {
+					t.Error(err)
+				}
+				fields++
+			}
+			r.Close()
+			if err != c.wantErr {
+				t.Fatalf("Case %d failed with %s", i, err)
+			}
+			if !reflect.DeepEqual(r.columnNames, c.wantColumns) {
+				t.Errorf("Case %d failed: expected \n%#v, got result \n%#v", i, c.wantColumns, r.columnNames)
+			}
+			if result.String() != c.wantFields {
+				t.Errorf("Case %d failed: expected \n%v\nGot result \n%v", i, c.wantFields, result.String())
+			}
+		})
+	}
+}
+
+func BenchmarkReaderBasic(b *testing.B) {
+	args := ReaderArgs{
+		FileHeaderInfo:             use,
+		RecordDelimiter:            "\n",
+		FieldDelimiter:             ",",
+		QuoteCharacter:             defaultQuoteCharacter,
+		QuoteEscapeCharacter:       defaultQuoteEscapeCharacter,
+		CommentCharacter:           defaultCommentCharacter,
+		AllowQuotedRecordDelimiter: false,
+		unmarshaled:                true,
+	}
+	f := openTestFile(b, "nyc-taxi-data-100k.csv")
+	r, err := NewReader(ioutil.NopCloser(bytes.NewBuffer(f)), &args)
+	if err != nil {
+		b.Fatalf("Reading init failed with %s", err)
+	}
+	defer r.Close()
+	b.ReportAllocs()
+	b.ResetTimer()
+	b.SetBytes(int64(len(f)))
+	var record sql.Record
+	for i := 0; i < b.N; i++ {
+		r, err = NewReader(ioutil.NopCloser(bytes.NewBuffer(f)), &args)
+		if err != nil {
+			b.Fatalf("Reading init failed with %s", err)
+		}
+		for err == nil {
+			record, err = r.Read(record)
+			if err != nil && err != io.EOF {
+				b.Fatalf("Reading failed with %s", err)
+			}
+		}
+		r.Close()
+	}
+}
+
+func BenchmarkReaderHuge(b *testing.B) {
+	args := ReaderArgs{
+		FileHeaderInfo:             use,
+		RecordDelimiter:            "\n",
+		FieldDelimiter:             ",",
+		QuoteCharacter:             defaultQuoteCharacter,
+		QuoteEscapeCharacter:       defaultQuoteEscapeCharacter,
+		CommentCharacter:           defaultCommentCharacter,
+		AllowQuotedRecordDelimiter: false,
+		unmarshaled:                true,
+	}
+	for n := 0; n < 11; n++ {
+		f := openTestFile(b, "nyc-taxi-data-100k.csv")
+		want := 309
+		for i := 0; i < n; i++ {
+			f = append(f, f...)
+			want *= 2
+		}
+		b.Run(fmt.Sprint(len(f)/(1<<10), "K"), func(b *testing.B) {
+			b.ReportAllocs()
+			b.SetBytes(int64(len(f)))
+			b.ResetTimer()
+			var record sql.Record
+			for i := 0; i < b.N; i++ {
+				r, err := NewReader(ioutil.NopCloser(bytes.NewBuffer(f)), &args)
+				if err != nil {
+					b.Fatalf("Reading init failed with %s", err)
+				}
+
+				got := 0
+				for err == nil {
+					record, err = r.Read(record)
+					if err != nil && err != io.EOF {
+						b.Fatalf("Reading failed with %s", err)
+					}
+					got++
+				}
+				r.Close()
+				if got != want {
+					b.Errorf("want %d records, got %d", want, got)
+				}
+			}
+		})
+	}
+}
+
+func BenchmarkReaderReplace(b *testing.B) {
+	args := ReaderArgs{
+		FileHeaderInfo:             use,
+		RecordDelimiter:            "^",
+		FieldDelimiter:             ",",
+		QuoteCharacter:             defaultQuoteCharacter,
+		QuoteEscapeCharacter:       defaultQuoteEscapeCharacter,
+		CommentCharacter:           defaultCommentCharacter,
+		AllowQuotedRecordDelimiter: false,
+		unmarshaled:                true,
+	}
+	f := openTestFile(b, "nyc-taxi-data-100k-single-delim.csv")
+	r, err := NewReader(ioutil.NopCloser(bytes.NewBuffer(f)), &args)
+	if err != nil {
+		b.Fatalf("Reading init failed with %s", err)
+	}
+	defer r.Close()
+	b.ReportAllocs()
+	b.ResetTimer()
+	b.SetBytes(int64(len(f)))
+	var record sql.Record
+	for i := 0; i < b.N; i++ {
+		r, err = NewReader(ioutil.NopCloser(bytes.NewBuffer(f)), &args)
+		if err != nil {
+			b.Fatalf("Reading init failed with %s", err)
+		}
+
+		for err == nil {
+			record, err = r.Read(record)
+			if err != nil && err != io.EOF {
+				b.Fatalf("Reading failed with %s", err)
+			}
+		}
+		r.Close()
+	}
+}
+
+func BenchmarkReaderReplaceTwo(b *testing.B) {
+	args := ReaderArgs{
+		FileHeaderInfo:             use,
+		RecordDelimiter:            "^Y",
+		FieldDelimiter:             ",",
+		QuoteCharacter:             defaultQuoteCharacter,
+		QuoteEscapeCharacter:       defaultQuoteEscapeCharacter,
+		CommentCharacter:           defaultCommentCharacter,
+		AllowQuotedRecordDelimiter: false,
+		unmarshaled:                true,
+	}
+	f := openTestFile(b, "nyc-taxi-data-100k-multi-delim.csv")
+	r, err := NewReader(ioutil.NopCloser(bytes.NewBuffer(f)), &args)
+	if err != nil {
+		b.Fatalf("Reading init failed with %s", err)
+	}
+	defer r.Close()
+	b.ReportAllocs()
+	b.ResetTimer()
+	b.SetBytes(int64(len(f)))
+	var record sql.Record
+	for i := 0; i < b.N; i++ {
+		r, err = NewReader(ioutil.NopCloser(bytes.NewBuffer(f)), &args)
+		if err != nil {
+			b.Fatalf("Reading init failed with %s", err)
+		}
+
+		for err == nil {
+			record, err = r.Read(record)
+			if err != nil && err != io.EOF {
+				b.Fatalf("Reading failed with %s", err)
+			}
+		}
+		r.Close()
+	}
+}

pkg/s3select/csv/record.go

@@ -27,7 +27,7 @@ import (
 	"github.com/minio/minio/pkg/s3select/sql"
 )
 
-// Record - is CSV record.
+// Record - is a CSV record.
 type Record struct {
 	columnNames  []string
 	csvRecord    []string

pkg/s3select/csv/recordtransform.go

@@ -0,0 +1,93 @@
+/*
+ * MinIO Cloud Storage, (C) 2019 MinIO, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package csv
+
+import (
+	"bytes"
+	"io"
+)
+
+// recordTransform will convert records to always have newline records.
+type recordTransform struct {
+	reader io.Reader
+	// recordDelimiter can be up to 2 characters.
+	recordDelimiter []byte
+	oneByte         []byte
+	useOneByte      bool
+}
+
+func (rr *recordTransform) Read(p []byte) (n int, err error) {
+	if rr.useOneByte {
+		p[0] = rr.oneByte[0]
+		rr.useOneByte = false
+		n, err = rr.reader.Read(p[1:])
+		n++
+	} else {
+		n, err = rr.reader.Read(p)
+	}
+
+	if err != nil {
+		return n, err
+	}
+
+	// Do nothing if record-delimiter is already newline.
+	if string(rr.recordDelimiter) == "\n" {
+		return n, nil
+	}
+
+	// Change record delimiters to newline.
+	if len(rr.recordDelimiter) == 1 {
+		for idx := 0; idx < len(p); {
+			i := bytes.Index(p[idx:], rr.recordDelimiter)
+			if i < 0 {
+				break
+			}
+			idx += i
+			p[idx] = '\n'
+		}
+		return n, nil
+	}
+
+	// 2 characters...
+	for idx := 0; idx < len(p); {
+		i := bytes.Index(p[idx:], rr.recordDelimiter)
+		if i < 0 {
+			break
+		}
+		idx += i
+
+		p[idx] = '\n'
+		p = append(p[:idx+1], p[idx+2:]...)
+		n--
+	}
+
+	if p[n-1] != rr.recordDelimiter[0] {
+		return n, nil
+	}
+
+	if _, err = rr.reader.Read(rr.oneByte); err != nil {
+		return n, err
+	}
+
+	if rr.oneByte[0] == rr.recordDelimiter[1] {
+		p[n-1] = '\n'
+		return n, nil
+	}
+
+	rr.useOneByte = true
+	return n, nil
+}

pkg/s3select/json/reader.go

@@ -33,7 +33,7 @@ type Reader struct {
 }
 
 // Read - reads single record.
-func (r *Reader) Read() (sql.Record, error) {
+func (r *Reader) Read(dst sql.Record) (sql.Record, error) {
 	v, ok := <-r.valueCh
 	if !ok {
 		if err := r.decoder.Err(); err != nil {
@@ -55,15 +55,25 @@ func (r *Reader) Read() (sql.Record, error) {
 		kvs = jstream.KVS{jstream.KV{Key: "_1", Value: v.Value}}
 	}
 
-	return &Record{
-		KVS:          kvs,
-		SelectFormat: sql.SelectFmtJSON,
-	}, nil
+	dstRec, ok := dst.(*Record)
+	if !ok {
+		dstRec = &Record{}
+	}
+	dstRec.KVS = kvs
+	dstRec.SelectFormat = sql.SelectFmtJSON
+	return dstRec, nil
 }
 
-// Close - closes underlaying reader.
+// Close - closes underlying reader.
 func (r *Reader) Close() error {
-	return r.readCloser.Close()
+	// Close the input.
+	// Potentially racy if the stream decoder is still reading.
+	err := r.readCloser.Close()
+	for range r.valueCh {
+		// Drain values so we don't leak a goroutine.
+		// Since we have closed the input, it should fail rather quickly.
+	}
+	return err
 }
 
 // NewReader - creates new JSON reader using readCloser.

pkg/s3select/json/reader_test.go

@@ -17,26 +17,30 @@
 package json
 
 import (
+	"bytes"
 	"io"
 	"io/ioutil"
 	"os"
 	"path/filepath"
 	"testing"
+
+	"github.com/minio/minio/pkg/s3select/sql"
 )
 
 func TestNewReader(t *testing.T) {
-	files, err := ioutil.ReadDir("data")
+	files, err := ioutil.ReadDir("testdata")
 	if err != nil {
 		t.Fatal(err)
 	}
 	for _, file := range files {
-		f, err := os.Open(filepath.Join("data", file.Name()))
+		f, err := os.Open(filepath.Join("testdata", file.Name()))
 		if err != nil {
 			t.Fatal(err)
 		}
 		r := NewReader(f, &ReaderArgs{})
+		var record sql.Record
 		for {
-			_, err = r.Read()
+			record, err = r.Read(record)
 			if err != nil {
 				break
 			}
@@ -47,3 +51,35 @@ func TestNewReader(t *testing.T) {
 		}
 	}
 }
+
+func BenchmarkReader(b *testing.B) {
+	files, err := ioutil.ReadDir("testdata")
+	if err != nil {
+		b.Fatal(err)
+	}
+	for _, file := range files {
+		b.Run(file.Name(), func(b *testing.B) {
+			f, err := ioutil.ReadFile(filepath.Join("testdata", file.Name()))
+			if err != nil {
+				b.Fatal(err)
+			}
+			b.SetBytes(int64(len(f)))
+			b.ReportAllocs()
+			b.ResetTimer()
+			var record sql.Record
+			for i := 0; i < b.N; i++ {
+				r := NewReader(ioutil.NopCloser(bytes.NewBuffer(f)), &ReaderArgs{})
+				for {
+					record, err = r.Read(record)
+					if err != nil {
+						break
+					}
+				}
+				r.Close()
+				if err != io.EOF {
+					b.Fatalf("Reading failed with %s, %s", err, file.Name())
+				}
+			}
+		})
+	}
+}

pkg/s3select/parquet/reader.go

@@ -33,7 +33,7 @@ type Reader struct {
 }
 
 // Read - reads single record.
-func (r *Reader) Read() (rec sql.Record, rerr error) {
+func (r *Reader) Read(dst sql.Record) (rec sql.Record, rerr error) {
 	parquetRecord, err := r.reader.Read()
 	if err != nil {
 		if err != io.EOF {
@@ -73,11 +73,20 @@ func (r *Reader) Read() (rec sql.Record, rerr error) {
 		return true
 	}
 
+	// Apply our range
 	parquetRecord.Range(f)
-	return &jsonfmt.Record{KVS: kvs, SelectFormat: sql.SelectFmtParquet}, nil
+
+	// Reuse destination if we can.
+	dstRec, ok := dst.(*jsonfmt.Record)
+	if !ok {
+		dstRec = &jsonfmt.Record{}
+	}
+	dstRec.SelectFormat = sql.SelectFmtParquet
+	dstRec.KVS = kvs
+	return dstRec, nil
 }
 
-// Close - closes underlaying readers.
+// Close - closes underlying readers.
 func (r *Reader) Close() error {
 	return r.reader.Close()
 }

pkg/s3select/select.go

@@ -34,7 +34,9 @@ import (
 )
 
 type recordReader interface {
-	Read() (sql.Record, error)
+	// Read a record.
+	// dst is optional but will be used if valid.
+	Read(dst sql.Record) (sql.Record, error)
 	Close() error
 }
 
@@ -399,6 +401,7 @@ func (s3Select *S3Select) Evaluate(w http.ResponseWriter) {
 		return true
 	}
 
+	var rec sql.Record
 	for {
 		if s3Select.statement.LimitReached() {
 			if err = writer.Finish(s3Select.getProgress()); err != nil {
@@ -408,7 +411,7 @@ func (s3Select *S3Select) Evaluate(w http.ResponseWriter) {
 			break
 		}
 
-		if inputRecord, err = s3Select.recordReader.Read(); err != nil {
+		if rec, err = s3Select.recordReader.Read(rec); err != nil {
 			if err != io.EOF {
 				break
 			}
@@ -431,7 +434,7 @@ func (s3Select *S3Select) Evaluate(w http.ResponseWriter) {
 			break
 		}
 
-		if inputRecord, err = s3Select.statement.EvalFrom(s3Select.Input.format, inputRecord); err != nil {
+		if inputRecord, err = s3Select.statement.EvalFrom(s3Select.Input.format, rec); err != nil {
 			break
 		}
 

pkg/s3select/select_test.go

@@ -18,6 +18,7 @@ package s3select
 
 import (
 	"bytes"
+	"fmt"
 	"io"
 	"io/ioutil"
 	"net/http"
@@ -108,26 +109,29 @@ func TestCSVInput(t *testing.T) {
 2.5,baz,true
 `)
 
-	for _, testCase := range testTable {
-		s3Select, err := NewS3Select(bytes.NewReader(testCase.requestXML))
-		if err != nil {
-			t.Fatal(err)
-		}
-
-		if err = s3Select.Open(func(offset, length int64) (io.ReadCloser, error) {
-			return ioutil.NopCloser(bytes.NewReader(csvData)), nil
-		}); err != nil {
-			t.Fatal(err)
-		}
-
-		w := &testResponseWriter{}
-		s3Select.Evaluate(w)
-		s3Select.Close()
-
-		if !reflect.DeepEqual(w.response, testCase.expectedResult) {
-			t.Fatalf("received response does not match with expected reply")
-		}
+	for i, testCase := range testTable {
+		t.Run(fmt.Sprint(i), func(t *testing.T) {
+			s3Select, err := NewS3Select(bytes.NewReader(testCase.requestXML))
+			if err != nil {
+				t.Fatal(err)
+			}
+
+			if err = s3Select.Open(func(offset, length int64) (io.ReadCloser, error) {
+				return ioutil.NopCloser(bytes.NewReader(csvData)), nil
+			}); err != nil {
+				t.Fatal(err)
+			}
+
+			w := &testResponseWriter{}
+			s3Select.Evaluate(w)
+			s3Select.Close()
+
+			if !reflect.DeepEqual(w.response, testCase.expectedResult) {
+				t.Errorf("received response does not match with expected reply\ngot: %#v\nwant:%#v", w.response, testCase.expectedResult)
+			}
+		})
 	}
+
 }
 
 func TestJSONInput(t *testing.T) {
@@ -191,26 +195,27 @@ func TestJSONInput(t *testing.T) {
 {"three":true,"two":"baz","one":2.5}
 `)
 
-	for _, testCase := range testTable {
-
-		s3Select, err := NewS3Select(bytes.NewReader(testCase.requestXML))
-		if err != nil {
-			t.Fatal(err)
-		}
+	for i, testCase := range testTable {
+		t.Run(fmt.Sprint(i), func(t *testing.T) {
+			s3Select, err := NewS3Select(bytes.NewReader(testCase.requestXML))
+			if err != nil {
+				t.Fatal(err)
+			}
 
-		if err = s3Select.Open(func(offset, length int64) (io.ReadCloser, error) {
-			return ioutil.NopCloser(bytes.NewReader(jsonData)), nil
-		}); err != nil {
-			t.Fatal(err)
-		}
+			if err = s3Select.Open(func(offset, length int64) (io.ReadCloser, error) {
+				return ioutil.NopCloser(bytes.NewReader(jsonData)), nil
+			}); err != nil {
+				t.Fatal(err)
+			}
 
-		w := &testResponseWriter{}
-		s3Select.Evaluate(w)
-		s3Select.Close()
+			w := &testResponseWriter{}
+			s3Select.Evaluate(w)
+			s3Select.Close()
 
-		if !reflect.DeepEqual(w.response, testCase.expectedResult) {
-			t.Fatalf("received response does not match with expected reply")
-		}
+			if !reflect.DeepEqual(w.response, testCase.expectedResult) {
+				t.Errorf("received response does not match with expected reply\ngot: %s\nwant:%s", string(w.response), string(testCase.expectedResult))
+			}
+		})
 	}
 }
 
@@ -268,45 +273,47 @@ func TestParquetInput(t *testing.T) {
 		},
 	}
 
-	for _, testCase := range testTable {
-		getReader := func(offset int64, length int64) (io.ReadCloser, error) {
-			testdataFile := "testdata.parquet"
-			file, err := os.Open(testdataFile)
-			if err != nil {
-				return nil, err
+	for i, testCase := range testTable {
+		t.Run(fmt.Sprint(i), func(t *testing.T) {
+			getReader := func(offset int64, length int64) (io.ReadCloser, error) {
+				testdataFile := "testdata.parquet"
+				file, err := os.Open(testdataFile)
+				if err != nil {
+					return nil, err
+				}
+
+				fi, err := file.Stat()
+				if err != nil {
+					return nil, err
+				}
+
+				if offset < 0 {
+					offset = fi.Size() + offset
+				}
+
+				if _, err = file.Seek(offset, os.SEEK_SET); err != nil {
+					return nil, err
+				}
+
+				return file, nil
 			}
 
-			fi, err := file.Stat()
+			s3Select, err := NewS3Select(bytes.NewReader(testCase.requestXML))
 			if err != nil {
-				return nil, err
-			}
-
-			if offset < 0 {
-				offset = fi.Size() + offset
+				t.Fatal(err)
 			}
 
-			if _, err = file.Seek(offset, os.SEEK_SET); err != nil {
-				return nil, err
+			if err = s3Select.Open(getReader); err != nil {
+				t.Fatal(err)
 			}
 
-			return file, nil
-		}
-
-		s3Select, err := NewS3Select(bytes.NewReader(testCase.requestXML))
-		if err != nil {
-			t.Fatal(err)
-		}
-
-		if err = s3Select.Open(getReader); err != nil {
-			t.Fatal(err)
-		}
+			w := &testResponseWriter{}
+			s3Select.Evaluate(w)
+			s3Select.Close()
 
-		w := &testResponseWriter{}
-		s3Select.Evaluate(w)
-		s3Select.Close()
-
-		if !reflect.DeepEqual(w.response, testCase.expectedResult) {
-			t.Fatalf("received response does not match with expected reply")
-		}
+			if !reflect.DeepEqual(w.response, testCase.expectedResult) {
+				t.Errorf("received response does not match with expected reply\ngot: %#v\nwant:%#v", w.response, testCase.expectedResult)
+			}
+		})
 	}
 }