remove usages of debug.FreeOSMemory() (#1301)

This can be detrimental to an application due to:
- Forces a GC on every execution and blocks until the GC is complete.
- Returns OS memory immediately instead of allowing the runtime to
  re-use it.

api-put-object-multipart.go

@@ -28,7 +28,6 @@ import (
 	"io/ioutil"
 	"net/http"
 	"net/url"
-	"runtime/debug"
 	"sort"
 	"strconv"
 	"strings"
@@ -98,7 +97,6 @@ func (c Client) putObjectMultipartNoStream(ctx context.Context, bucketName, obje
 
 	// Create a buffer.
 	buf := make([]byte, partSize)
-	defer debug.FreeOSMemory()
 
 	for partNumber <= totalPartsCount {
 		// Choose hash algorithms to be calculated by hashCopyN,

api-put-object-streaming.go

@@ -24,7 +24,6 @@ import (
 	"fmt"
 	"io"
 	"net/http"
-	"runtime/debug"
 	"sort"
 	"strings"
 
@@ -262,7 +261,6 @@ func (c Client) putObjectMultipartStreamOptionalChecksum(ctx context.Context, bu
 
 	// Create a buffer.
 	buf := make([]byte, partSize)
-	defer debug.FreeOSMemory()
 
 	// Avoid declaring variables in the for loop
 	var md5Base64 string
@@ -386,7 +384,6 @@ func (c Client) putObject(ctx context.Context, bucketName, objectName string, re
 	if opts.SendContentMd5 {
 		// Create a buffer.
 		buf := make([]byte, size)
-		defer debug.FreeOSMemory()
 
 		length, rErr := io.ReadFull(reader, buf)
 		if rErr != nil && rErr != io.ErrUnexpectedEOF {

api-put-object.go

@@ -25,7 +25,6 @@ import (
 	"fmt"
 	"io"
 	"net/http"
-	"runtime/debug"
 	"sort"
 	"time"
 
@@ -252,7 +251,6 @@ func (c Client) putObjectMultipartStreamNoLength(ctx context.Context, bucketName
 
 	// Create a buffer.
 	buf := make([]byte, partSize)
-	defer debug.FreeOSMemory()
 
 	for partNumber <= totalPartsCount {
 		length, rerr := io.ReadFull(reader, buf)