Spring batch - run multiple instances of same job same time

I am using Spring frameWork based Web application. Using batch upload functionality from UI, to upload file, processing and insert into table. I am using spring batch for this. But, getting a issue that if a user upload a file and spring batch job trigger from controller and if same time second user try to upload file, it is not starting. Looks like second request didn't trigger because job is already running and second request got timedout. HoW to handle this situation? HoW to run multiple instances of same job at same time. So, multiple users can upload files at same time. Please advise.