The use of $|++ is not useless. I can agree there is no need for it to appear in my client code, but there is a good reason for it to appear in the server code.

From time to time, I saw posts complaining their codes are not working simply because of the confusion caused by not-flushed debug infos, which can be easily fixed by setting $|. It is a better practice in multi-threading programming ,to turn on autoflush regardless, unless it is forbidden by the nature of your application. Instead of saying it is useless, I see it as a better style.

I didn't notice the original post is reading from STDIN, instead of the client socket. That's my mistake, but it is understandable, as that doesn't make sense there. I think that's just a simple mistake, and the original author's purpose is to read from the client. However as I pointed out in my original post, his structure is wrong, even changing it to read from client, he will still stuck communicating with the first client, and not going back to accept() until the first client ended.

BTW, next time there is no need to tell me about the down vote. I may think about the reason for getting down voted, but not interested in knowing who did it. Please keep it for your privacy.

As for the technical side, I am a strong promoter for threads, and that was where I was getting. I see it much more important to get the direction correct, than anything else.