Can use asynchronous operation of CEP to realize multi threading?
For example: draw ten rectangles at the same time
No, you can not.
The applications object model works synchronously same as Extendscript.
CEP_7_Feature_List
....
Support not enforcing FIFO queueing of evalScript() requests across extensions.
o By default, the evalScript requests are served in First-In-First-Out order across extensions. For host applications which can execute evalScript requests asynchronously, they have the option to control the order according to their use cases.
In CEP side, execute evalScript method works non blocking. But the Extendscript DOM works blocking.