[volume] Reduce the number of buffers for uploading one chunk (#5458)

weed/util/buffer_pool/sync_pool.go

@@ -0,0 +1,20 @@
+package buffer_pool
+
+import (
+	"bytes"
+	"sync"
+)
+
+var syncPool = sync.Pool{
+	New: func() interface{} {
+		return new(bytes.Buffer)
+	},
+}
+
+func SyncPoolGetBuffer() *bytes.Buffer {
+	return syncPool.Get().(*bytes.Buffer)
+}
+
+func SyncPoolPutBuffer(buffer *bytes.Buffer) {
+	syncPool.Put(buffer)
+}