NF test_flow_dir runtime Segmentation fault

[Yongeverhuang]

NF test_flow_dir could not run likes others simple_forward NF. When start it in onvm 19.07, it lanches in stdout stats, but it will popup exception quickly likes the picture. Before pktgen generates packets to it, it performances normal, and then meet error. Any cases missed when create test_flow_dir?
Current Behavior