what u used is not idle task , it is some import on startup
NewPeriodicTask should be used for example OnApplicationStartupComplete
and there are more things to consider there
and creating 20000 items will take time ......
Hello!
You can mark it as closed as option. If document is connected with other documents you can not delete it so you will not be able to delete PO, as you will not be able to remove Goods receipt...