Narrowing down the debugging space of slow search response time

When using search engines, users often care about search response time (SRT) in addition to result accuracy. It is thus the operators' responsibility to closely monitor and improving SRT. The first critical step of improving SRT is to pinpoint the root causes of slow SRT. However, this task is very challenging because SRT can be impacted by many factors, e.g., networks, data centers, browsers, and the page content. In this paper, we propose FOCUS, a systematic framework to narrow down the debugging space of slow SRT by identifying the bottleneck of slow SRT regarding various factors. The bottleneck provides operators more specific direction for further investigation. We deployed FOCUS in a global top search engine. Based on the output of FOCUS, operators successfully identified four potential causes which would not have been easy to find without FOCUS. Our what-if simulation analysis shows that, the proposed solutions, focusing on these bottlenecks, can improve SRT significantly, and they are more effective than some ad hoc solutions.