lib/protoparser/clusternative: reuse unmarshalWork in order to reduce memory allocations

lib/protoparser/clusternative/streamparser.go

@@ -30,10 +30,7 @@ func ParseStream(bc *handshake.BufferedConn, callback func(rows []storage.Metric
 		callbackErr     error
 	)
 	for {
-		// Do not use unmarshalWork pool, since every unmarshalWork structure usually occupies
-		// big amounts of memory (more than consts.MaxInsertPacketSizeForVMStorage bytes).
-		// The pool would result in increased memory usage.
-		uw := &unmarshalWork{}
+		uw := getUnmarshalWork()
 		uw.callback = func(rows []storage.MetricRow) {
 			if err := callback(rows); err != nil {
 				processErrors.Inc()
@@ -138,6 +135,14 @@ type unmarshalWork struct {
 	mrs      []storage.MetricRow
 }
 
+func (uw *unmarshalWork) reset() {
+	uw.wg = nil
+	uw.callback = nil
+	// Zero reqBuf, since it may occupy big amounts of memory (consts.MaxInsertPacketSizeForVMStorage).
+	uw.reqBuf = nil
+	uw.mrs = uw.mrs[:0]
+}
+
 // Unmarshal implements common.UnmarshalWork
 func (uw *unmarshalWork) Unmarshal() {
 	reqBuf := uw.reqBuf
@@ -157,6 +162,22 @@ func (uw *unmarshalWork) Unmarshal() {
 	}
 	wg := uw.wg
 	wg.Done()
+	putUnmarshalWork(uw)
 }
 
 const maxRowsPerCallback = 10000
+
+func getUnmarshalWork() *unmarshalWork {
+	v := unmarshalWorkPool.Get()
+	if v == nil {
+		return &unmarshalWork{}
+	}
+	return v.(*unmarshalWork)
+}
+
+func putUnmarshalWork(uw *unmarshalWork) {
+	uw.reset()
+	unmarshalWorkPool.Put(uw)
+}
+
+var unmarshalWorkPool sync.Pool