The back-end job processing infrastructure allows up to 10 concurrent activities happening at once. Any request past those 10 get queued up and will be handled in order. This is why you may see ‘Starting’ vs. ‘Started’ in the job status: the jobs that are starting haven’t started because of the 10 concurrent limitation.
One thing you should realize is that resources are not infinite and when doing large scale analytics, the platform has to be conscious of those limited resources. So the default is 10 concurrent threads, but I believe that there may be a configuration option to change that value. I’m not sure if that configuration option is user-defined.
-Chris