3 files changed, 16 insertions, 11 deletions
diff --git a/plumbing/format/objfile/reader.go b/plumbing/format/objfile/reader.go
index b6b2ca0..d7932f4 100644
--- a/plumbing/format/objfile/reader.go
+++ b/plumbing/format/objfile/reader.go
@@ -1,13 +1,13 @@
 package objfile
 
 import (
-	"compress/zlib"
 	"errors"
 	"io"
 	"strconv"
 
 	"github.com/go-git/go-git/v5/plumbing"
 	"github.com/go-git/go-git/v5/plumbing/format/packfile"
+	"github.com/go-git/go-git/v5/utils/sync"
 )
 
 var (
@@ -20,20 +20,22 @@ var (
 // Reader implements io.ReadCloser. Close should be called when finished with
 // the Reader. Close will not close the underlying io.Reader.
 type Reader struct {
-	multi  io.Reader
-	zlib   io.ReadCloser
-	hasher plumbing.Hasher
+	multi   io.Reader
+	zlib    io.Reader
+	zlibref sync.ZLibReader
+	hasher  plumbing.Hasher
 }
 
 // NewReader returns a new Reader reading from r.
 func NewReader(r io.Reader) (*Reader, error) {
-	zlib, err := zlib.NewReader(r)
+	zlib, err := sync.GetZlibReader(r)
 	if err != nil {
 		return nil, packfile.ErrZLib.AddDetails(err.Error())
 	}
 
 	return &Reader{
-		zlib: zlib,
+		zlib:    zlib.Reader,
+		zlibref: zlib,
 	}, nil
 }
 
@@ -110,5 +112,6 @@ func (r *Reader) Hash() plumbing.Hash {
 // Close releases any resources consumed by the Reader. Calling Close does not
 // close the wrapped io.Reader originally passed to NewReader.
 func (r *Reader) Close() error {
-	return r.zlib.Close()
+	sync.PutZlibReader(r.zlibref)
+	return nil
 }
diff --git a/plumbing/format/objfile/reader_test.go b/plumbing/format/objfile/reader_test.go
index d697d54..5526f7f 100644
--- a/plumbing/format/objfile/reader_test.go
+++ b/plumbing/format/objfile/reader_test.go
@@ -5,7 +5,6 @@ import (
 	"encoding/base64"
 	"fmt"
 	"io"
-	"io/ioutil"
 
 	"github.com/go-git/go-git/v5/plumbing"
 
@@ -36,7 +35,7 @@ func testReader(c *C, source io.Reader, hash plumbing.Hash, t plumbing.ObjectTyp
 	c.Assert(typ, Equals, t)
 	c.Assert(content, HasLen, int(size))
 
-	rc, err := ioutil.ReadAll(r)
+	rc, err := io.ReadAll(r)
 	c.Assert(err, IsNil)
 	c.Assert(rc, DeepEquals, content, Commentf("%scontent=%s, expected=%s", base64.StdEncoding.EncodeToString(rc), base64.StdEncoding.EncodeToString(content)))
 
diff --git a/plumbing/format/objfile/writer.go b/plumbing/format/objfile/writer.go
index 2a96a43..0d0f154 100644
--- a/plumbing/format/objfile/writer.go
+++ b/plumbing/format/objfile/writer.go
@@ -7,6 +7,7 @@ import (
 	"strconv"
 
 	"github.com/go-git/go-git/v5/plumbing"
+	"github.com/go-git/go-git/v5/utils/sync"
 )
 
 var (
@@ -18,9 +19,9 @@ var (
 // not close the underlying io.Writer.
 type Writer struct {
 	raw    io.Writer
-	zlib   io.WriteCloser
 	hasher plumbing.Hasher
 	multi  io.Writer
+	zlib   *zlib.Writer
 
 	closed  bool
 	pending int64 // number of unwritten bytes
@@ -31,9 +32,10 @@ type Writer struct {
 // The returned Writer implements io.WriteCloser. Close should be called when
 // finished with the Writer. Close will not close the underlying io.Writer.
 func NewWriter(w io.Writer) *Writer {
+	zlib := sync.GetZlibWriter(w)
 	return &Writer{
 		raw:  w,
-		zlib: zlib.NewWriter(w),
+		zlib: zlib,
 	}
 }
 
@@ -100,6 +102,7 @@ func (w *Writer) Hash() plumbing.Hash {
 // Calling Close does not close the wrapped io.Writer originally passed to
 // NewWriter.
 func (w *Writer) Close() error {
+	defer sync.PutZlibWriter(w.zlib)
 	if err := w.zlib.Close(); err != nil {
 		return err
 	}