2 files changed, 32 insertions, 4 deletions
diff --git a/rlp/encode.go b/rlp/encode.go
index b525ae4e7..a0531af01 100644
--- a/rlp/encode.go
+++ b/rlp/encode.go
@@ -90,8 +90,8 @@ func Encode(w io.Writer, val interface{}) error {
 		return outer.encode(val)
 	}
 	eb := encbufPool.Get().(*encbuf)
-	eb.reset()
 	defer encbufPool.Put(eb)
+	eb.reset()
 	if err := eb.encode(val); err != nil {
 		return err
 	}
@@ -102,8 +102,8 @@ func Encode(w io.Writer, val interface{}) error {
 // Please see the documentation of Encode for the encoding rules.
 func EncodeToBytes(val interface{}) ([]byte, error) {
 	eb := encbufPool.Get().(*encbuf)
-	eb.reset()
 	defer encbufPool.Put(eb)
+	eb.reset()
 	if err := eb.encode(val); err != nil {
 		return nil, err
 	}
@@ -288,8 +288,13 @@ type encReader struct {
 func (r *encReader) Read(b []byte) (n int, err error) {
 	for {
 		if r.piece = r.next(); r.piece == nil {
-			encbufPool.Put(r.buf)
-			r.buf = nil
+			// Put the encode buffer back into the pool at EOF when it
+			// is first encountered. Subsequent calls still return EOF
+			// as the error but the buffer is no longer valid.
+			if r.buf != nil {
+				encbufPool.Put(r.buf)
+				r.buf = nil
+			}
 			return n, io.EOF
 		}
 		nn := copy(b[n:], r.piece)
diff --git a/rlp/encode_test.go b/rlp/encode_test.go
index 60bd95692..b550d4303 100644
--- a/rlp/encode_test.go
+++ b/rlp/encode_test.go
@@ -23,6 +23,7 @@ import (
 	"io"
 	"io/ioutil"
 	"math/big"
+	"sync"
 	"testing"
 )
 
@@ -306,3 +307,25 @@ func TestEncodeToReaderPiecewise(t *testing.T) {
 		return output, nil
 	})
 }
+
+// This is a regression test verifying that encReader
+// returns its encbuf to the pool only once.
+func TestEncodeToReaderReturnToPool(t *testing.T) {
+	buf := make([]byte, 50)
+	wg := new(sync.WaitGroup)
+	for i := 0; i < 5; i++ {
+		wg.Add(1)
+		go func() {
+			for i := 0; i < 1000; i++ {
+				_, r, _ := EncodeToReader("foo")
+				ioutil.ReadAll(r)
+				r.Read(buf)
+				r.Read(buf)
+				r.Read(buf)
+				r.Read(buf)
+			}
+			wg.Done()
+		}()
+	}
+	wg.Wait()
+}