app/{vminsert,vmstorage}: add comments on why storage.AddRows() is called without limiting the number of concurrent calls

app/vminsert/common/insert_ctx.go

@@ -144,6 +144,9 @@ func (ctx *InsertCtx) FlushBufs() error {
 			return nil
 		}
 	}
+	// There is no need in limiting the number of concurrent calls to vmstorage.AddRows() here,
+	// since the number of concurrent FlushBufs() calls should be already limited via writeconcurrencylimiter
+	// used at every ParseStream() call under lib/protoparser/*/streamparser.go
 	err := vmstorage.AddRows(ctx.mrs)
 	ctx.Reset(0)
 	if err == nil {

app/vminsert/common/streamaggr.go

@@ -111,6 +111,8 @@ func pushAggregateSeries(tss []prompbmarshal.TimeSeries) {
 			return
 		}
 	}
+	// There is no need in limiting the number of concurrent calls to vmstorage.AddRows() here,
+	// since the number of concurrent pushAggregateSeries() calls should be already limited by lib/streamaggr.
 	if err := vmstorage.AddRows(ctx.mrs); err != nil {
 		logger.Errorf("cannot flush aggregate series: %s", err)
 	}

app/vmstorage/main.go

@@ -147,6 +147,8 @@ var WG syncwg.WaitGroup
 var resetResponseCacheIfNeeded func(mrs []storage.MetricRow)
 
 // AddRows adds mrs to the storage.
+//
+// The caller should limit the number of concurrent calls to AddRows() in order to limit memory usage.
 func AddRows(mrs []storage.MetricRow) error {
 	if Storage.IsReadOnly() {
 		return errReadOnly