Each IT infrastructure includes heterogeneous resources which serve different purposes. Some resources might be more suited for RAM consuming tasks, other might include a secured database, other offer low latency to the customer and other might have bigger bandwidth.
This article will take as an example the need to access a database or any specific resource for a given task. A selection script will ensure this task will be executed on the server hosting this resource but other requirements have to be considered.
What if there are other tasks waiting and yours has higher priority? What if your task requires the whole capacity of the machine?