better handling of cdr replication goroutines

possible fixes the issue #423

engine/cdrs.go

@@ -451,7 +451,10 @@ func (self *CdrServer) replicateCdr(cdr *CDR) error {
 			}
 			body = jsn
 		}
-		errChan := make(chan error)
+		var errChan chan error
+		if rplCfg.Synchronous {
+			errChan = make(chan error)
+		}
 		go func(body interface{}, rplCfg *config.CdrReplicationCfg, content string, errChan chan error) {
 			fallbackPath := path.Join(
 				self.cgrCfg.HttpFailedDir,
@@ -462,10 +465,13 @@ func (self *CdrServer) replicateCdr(cdr *CDR) error {
 			if err != nil {
 				utils.Logger.Err(fmt.Sprintf(
 					"<CDRReplicator> Replicating CDR: %+v, got error: %s", cdr, err.Error()))
-				errChan <- err
+				if rplCfg.Synchronous {
+					errChan <- err
+				}
+			}
+			if rplCfg.Synchronous {
+				errChan <- nil
 			}
-			errChan <- nil
-
 		}(body, rplCfg, content, errChan)
 		if rplCfg.Synchronous { // Synchronize here
 			<-errChan