You shouldn’t seek for “parallelism”.
Katalon’s Test Suite Collection features Parallel execution. On a single PC box, it won’t make the your tests run faster at all, it might be even slower than a sequetial execution. The Parallel Execution feature is just useless.
I have every tried to make use of multi-threading in a Test Case execution. See
Multi-threading did not help speeding up. Muti-threading is difficult to implement. Multi-threading is fragile, it breaks so easily.
In case that your test runs 15 hours you might desparately require parallelism. Then you would need to split your task into several portions and distribute the processings on to multiple machines: 2 boxes, 4 boxes, 8 boxes, … When all of distributed processes finished, you need to aggregate the test results and compile them into one. You need a Map-Reduce architecture like Hadoop. Katalon Studio does not support such approach at all. You have to invent all for yourself. I suppose you don’t want such crazy complex idea now.