The program used to run very fast every time, but yesterday it suddenly ran slowly. Is it because the machine shared with others has been running too frequently, causing a significant drop in performance? To be honest, I was a little desperate at the time.
But today I remembered to adjust num_worker from 2 to 0, and unexpectedly it ran very fast again. It seems that if the machine performance is good, it is not necessary to set num_worker higher. It still depends on the actual situation.