An Experimental Study on Half-Closed TCP Connections in Public Cloud Gateways

Many TCP-based services, such as social media and e-commerce platforms, depend on Load Balancer(LB) or Network Address Translation(NAT) gateways to manage end-user connections. In this paper, we conduct an in-depth study on the prevalence and impact of half-closed TCP connections in public cloud LB gateways. Our trace data analysis reveals that, on average, these connections account for 9.26% of new connections and consume 16.14% more memory resources compared to fully active connections. Through a series of experiments, we investigate the role of popular HTTP libraries in causing half-closed connections and identify specific implementation patterns that contribute to this behavior. To address this, we propose feasible approaches and demo code to reduce the number of such half-closed connections on both the gateway and client sides.