How to Generate a Level without Lagging the Server?

How to Generate a Level without Lagging the Server?
I want to create a new Thread but how?

You'd go about using pthreads, so I think you should have a look at this guide first:
http://pthreads.org/tutorials/start.html

Thank you so much!

And I tried it caused program crash( not PHP error crash ).

Could you send me your code and maybe a crash log?

Not code crash, it is PHP.exe crashed.

Not code crash, it is PHP.exe crashed.

Oh that's strange. Recently there are crashs being reported on pthread's GitHub issue tracker:
https://github.com/krakjoe/pthreads/issues/180
Could you try again with the latest pthreads dll? Here they describe the installation for Windows PHP installations, you may apply it to your PM-MP's php directory

I don't know what will happen in Linux.

Do you have a test server? I'd suggest setting up a simple LAMP instance in VirtualBox or VMWare for that purpose.

howdoes your autoline work?

I guess it will also crash the server. Just a guess.

I'm able to run my Timer plugin in PHP using my system's PHP installation. It should be worth a try to test your script in another environment

How to do folder copy in PHP?

@VanishedKevin: The code from this StackOverflow answer should work out

Maybe I can just make a pre-generated world and when I wanna generate it, I just tp all players to spawn, unload the world, remove world folder and copy pre-generated folder in and load it back!

Unload the main world? Would that work without a server restart?

Nah, it is a secret. It is a multi-world server. And I plan to do auto map reset.