Available schedulers

The available MA workflow schedulers are:

• A basic scheduler (option -basic or default choice): this scheduler manages the precedence constraints between the tasks. The priority between tasks within a DAG is set according to the HEFT [24] heuristic (Heterogeneous Earliest Finish Time). When a task is ready to be executed (i.e., the preceding tasks are completed) the ready task with the highest HEFT rank is notified to the client for execution without specifying a resource. Then the client performs a standard DIET request, which will be scheduled according to the deployed plugin-scheduler (see Subsection 15.6.2).

• A Multi-HEFT scheduler (option -heft): this scheduler applies the HEFT heuristic to all workflows submitted by different clients to the MA. This means that the priorities assigned by the HEFT heuristic are used to order the tasks of all DAGs processed by the MA and, following this order, the tasks are mapped to the first available resource.

• A Multi-AgingHEFT scheduler (option -aging_heft): this scheduler is similar to Multi-HEFT but applies a correction factor to the priorities calculated by the HEFT algorithm. This factor is based on the age of the DAG, i.e., the time since it was submitted to the scheduler. Compared to Multi-HEFT this scheduler increases the priority of the tasks of a DAG submitted earlier than other DAGs.

• A FOFT (Fairness on Finish Time) scheduler (option -fairness): this scheduler uses another heuristic to apply a correction factor to the priorities calculated by the HEFT algorithm. The factor is based on the slowdown of the DAG, calculated by comparing the earliest finish time of the tasks in the same environment without any other concurrent workflow and the actual estimated finish time.