如何限制搜索结果计数或设置haystack的超时?

I use haystack with whoosh to search my company's code, every file per index. Most of the time, it works fine. However, when I search with some common keyword like 'port', the seaching takes 5 mins to finish, and the CPU is 100%. I think this is because the result count is too large(5000+ for keyword port). Indeed, I don't need so many results, maybe 100 or so is enough. How can I set the limit? or timeout is also OK.I use haystack with whoosh to search my company