Fix SkipReader performance with small initial read (#20030)

If `SkipReader` is called with a small initial buffer it may be doing a huge number if Reads to skip the requested number of bytes. If a small buffer is provided grab a 32K buffer and use that.

Fixes slow execution of `testAPIGetObjectWithMPHandler`.

Bonuses:

* Use `-short` with `-race` test.
* Do all suite test types with `-short`.
* Enable compressed+encrypted in `testAPIGetObjectWithMPHandler`.
* Disable big file tests in `testAPIGetObjectWithMPHandler` when using `-short`.

buildscripts/race.sh

@@ -6,5 +6,5 @@ export GORACE="history_size=7"
 export MINIO_API_REQUESTS_MAX=10000
 
 for d in $(go list ./...); do
-	CGO_ENABLED=1 go test -v -race --timeout 100m "$d"
+	CGO_ENABLED=1 go test -v -race -short --timeout 100m "$d"
 done

cmd/dummy-data-generator_test.go

@@ -61,10 +61,9 @@ func NewDummyDataGen(totalLength, skipOffset int64) io.ReadSeeker {
 	}
 
 	skipOffset %= int64(len(alphabets))
-	as := make([]byte, 2*len(alphabets))
-	copy(as, alphabets)
-	copy(as[len(alphabets):], alphabets)
-	b := as[skipOffset : skipOffset+int64(len(alphabets))]
+	const multiply = 100
+	as := bytes.Repeat(alphabets, multiply)
+	b := as[skipOffset : skipOffset+int64(len(alphabets)*(multiply-1))]
 	return &DummyDataGen{
 		length: totalLength,
 		b:      b,

cmd/object-handlers_test.go

@@ -692,8 +692,8 @@ func testAPIGetObjectWithMPHandler(obj ObjectLayer, instanceType, bucketName str
 		{"small-1", []int64{509}, make(map[string]string)},
 		{"small-2", []int64{5 * oneMiB}, make(map[string]string)},
 		// // // cases 4-7: multipart part objects
-		{"mp-0", []int64{5 * oneMiB, 1}, make(map[string]string)},
-		{"mp-1", []int64{5*oneMiB + 1, 1}, make(map[string]string)},
+		{"mp-0", []int64{5 * oneMiB, 10}, make(map[string]string)},
+		{"mp-1", []int64{5*oneMiB + 1, 10}, make(map[string]string)},
 		{"mp-2", []int64{5487701, 5487799, 3}, make(map[string]string)},
 		{"mp-3", []int64{10499807, 10499963, 7}, make(map[string]string)},
 		// cases 8-11: small single part objects with encryption
@@ -702,17 +702,13 @@ func testAPIGetObjectWithMPHandler(obj ObjectLayer, instanceType, bucketName str
 		{"enc-small-1", []int64{509}, mapCopy(metaWithSSEC)},
 		{"enc-small-2", []int64{5 * oneMiB}, mapCopy(metaWithSSEC)},
 		// cases 12-15: multipart part objects with encryption
-		{"enc-mp-0", []int64{5 * oneMiB, 1}, mapCopy(metaWithSSEC)},
-		{"enc-mp-1", []int64{5*oneMiB + 1, 1}, mapCopy(metaWithSSEC)},
+		{"enc-mp-0", []int64{5 * oneMiB, 10}, mapCopy(metaWithSSEC)},
+		{"enc-mp-1", []int64{5*oneMiB + 1, 10}, mapCopy(metaWithSSEC)},
 		{"enc-mp-2", []int64{5487701, 5487799, 3}, mapCopy(metaWithSSEC)},
 		{"enc-mp-3", []int64{10499807, 10499963, 7}, mapCopy(metaWithSSEC)},
 	}
-	// SSEC can't be used with compression
-	globalCompressConfigMu.Lock()
-	globalCompressEnabled := globalCompressConfig.Enabled
-	globalCompressConfigMu.Unlock()
-	if globalCompressEnabled {
-		objectInputs = objectInputs[0:8]
+	if testing.Short() {
+		objectInputs = append(objectInputs[0:5], objectInputs[8:11]...)
 	}
 	// iterate through the above set of inputs and upload the object.
 	for _, input := range objectInputs {
@@ -768,6 +764,7 @@ func testAPIGetObjectWithMPHandler(obj ObjectLayer, instanceType, bucketName str
 			readers = append(readers, NewDummyDataGen(p, cumulativeSum))
 			cumulativeSum += p
 		}
+
 		refReader := io.LimitReader(ioutilx.NewSkipReader(io.MultiReader(readers...), off), length)
 		if ok, msg := cmpReaders(refReader, rec.Body); !ok {
 			t.Fatalf("(%s) Object: %s Case %d ByteRange: %s --> data mismatch! (msg: %s)", instanceType, oi.objectName, i+1, byteRange, msg)

cmd/object_api_suite_test.go

@@ -559,21 +559,17 @@ func execExtended(t *testing.T, fn func(t *testing.T, init func(), bucketOptions
 	t.Run("default", func(t *testing.T) {
 		fn(t, nil, MakeBucketOptions{})
 	})
-	t.Run("defaultVerioned", func(t *testing.T) {
+	t.Run("default+versioned", func(t *testing.T) {
 		fn(t, nil, MakeBucketOptions{VersioningEnabled: true})
 	})
 
-	if testing.Short() {
-		return
-	}
-
 	t.Run("compressed", func(t *testing.T) {
 		fn(t, func() {
 			resetCompressEncryption()
 			enableCompression(t, false, []string{"*"}, []string{"*"})
 		}, MakeBucketOptions{})
 	})
-	t.Run("compressedVerioned", func(t *testing.T) {
+	t.Run("compressed+versioned", func(t *testing.T) {
 		fn(t, func() {
 			resetCompressEncryption()
 			enableCompression(t, false, []string{"*"}, []string{"*"})
@@ -588,7 +584,7 @@ func execExtended(t *testing.T, fn func(t *testing.T, init func(), bucketOptions
 			enableEncryption(t)
 		}, MakeBucketOptions{})
 	})
-	t.Run("encryptedVerioned", func(t *testing.T) {
+	t.Run("encrypted+versioned", func(t *testing.T) {
 		fn(t, func() {
 			resetCompressEncryption()
 			enableEncryption(t)
@@ -603,7 +599,7 @@ func execExtended(t *testing.T, fn func(t *testing.T, init func(), bucketOptions
 			enableCompression(t, true, []string{"*"}, []string{"*"})
 		}, MakeBucketOptions{})
 	})
-	t.Run("compressed+encryptedVerioned", func(t *testing.T) {
+	t.Run("compressed+encrypted+versioned", func(t *testing.T) {
 		fn(t, func() {
 			resetCompressEncryption()
 			enableCompression(t, true, []string{"*"}, []string{"*"})

internal/ioutil/ioutil.go

@@ -256,16 +256,27 @@ func (s *SkipReader) Read(p []byte) (int, error) {
 	if l == 0 {
 		return 0, nil
 	}
+	if s.skipCount > 0 {
+		tmp := p
+		if s.skipCount > l && l < copyBufferSize {
+			// We may get a very small buffer, so we grab a temporary buffer.
+			bufp := copyBufPool.Get().(*[]byte)
+			buf := *bufp
+			tmp = buf[:copyBufferSize]
+			defer copyBufPool.Put(bufp)
+			l = int64(len(tmp))
+		}
 		for s.skipCount > 0 {
 			if l > s.skipCount {
 				l = s.skipCount
 			}
-		n, err := s.Reader.Read(p[:l])
+			n, err := s.Reader.Read(tmp[:l])
 			if err != nil {
 				return 0, err
 			}
 			s.skipCount -= int64(n)
 		}
+	}
 	return s.Reader.Read(p)
 }
 
@@ -274,9 +285,11 @@ func NewSkipReader(r io.Reader, n int64) io.Reader {
 	return &SkipReader{r, n}
 }
 
+const copyBufferSize = 32 * 1024
+
 var copyBufPool = sync.Pool{
 	New: func() interface{} {
-		b := make([]byte, 32*1024)
+		b := make([]byte, copyBufferSize)
 		return &b
 	},
 }
@@ -285,6 +298,7 @@ var copyBufPool = sync.Pool{
 func Copy(dst io.Writer, src io.Reader) (written int64, err error) {
 	bufp := copyBufPool.Get().(*[]byte)
 	buf := *bufp
+	buf = buf[:copyBufferSize]
 	defer copyBufPool.Put(bufp)
 
 	return io.CopyBuffer(dst, src, buf)