Parallelization lets multiple actions execute simultaneously or in different possible orders. Timeline diagrams separate such actions from sequential work and make their ordering visible. section 15.22
Analyze parallel work by:
- Breaking composite operations into atomic actions, including hidden reads and writes. section 15.22
- Drawing independent actions on separate timelines and marking required order with dotted lines. section 15.22
- Checking whether alternative orders are impossible, desirable, or undesirable before simplifying the diagram. section 15.22
Two web requests
Waiting for cost_ajax() and shipping_ajax() sequentially adds their response times. Running them in parallel takes the longer response time, but responses can return out of order; coordination preserves correctness while retaining the speed benefit. section 17.8 section 17.13
Use the timeline figure to compare parallel execution with the ordering required for correct results. section 17.13
