You’re sending the poor newbie on a journey of self-discovering of picklable-non-picklable, passing of arguments back and forth, working with Queues (which have well-known yet undocumented race conditions), missing exception stack traces due to dead processes and all sorts of useless garbage they don’t need to know about.

Also what exactly would that newbie be building that starts and stops threads depending on the system load? What kind of a contraption is that? What are you doing?

Finallizing all of the above: under the circumstance you mentioned, you should check whether you have just seriously over-architected the solution.

I understand you are worried about newbies misuse APIs. You remind me that I should add a warning to inform the sample code in this article should not use in programs. Thanks.

Also, I did not advocate a newbie should start and stop threads by themselves. I want to say I agree that we should use high-level APIs in most cases, but, in some cases, we may need to use low-level APIs to achieve our missions. I am unwilling to limit what kind of APIs should use. In my opinion, like you said: "you have just seriously over-architected the solution," we should be careful to use APIs. Even though high-level APIs are safer, programmers may misuse them.

Just create a new pool and close the previous one, depending of the system load.

I think this is not an excellent solution. You have to wait for all threads finish. I agree that we should use high-level API in most of the time, but, in some cases, we still need low-level APIs to support us to reach some goals.