Definition
Concurrent thinking is the process of recognising and applying the concept of concurrent processing—executing more than one task at the same time. It involves identifying patterns in problems where concurrency can be applied, allowing for more efficient problem-solving.
Understanding Concurrent Thinking
Worked Example
Worked Example: Recording Car Information
Scenario: for each passing car, record number plate and colour.
Why this helps:
• Better data consistency (plate matches colour)
• More efficient handling of each event
• Less risk of missing information
Scenario: for each passing car, record number plate and colour.
| Approach | What happens | Typical outcome |
|---|---|---|
| Sequential | Record all plates first, then try colours later | Missing/mismatched data likely |
| Concurrent thinking | Capture plate + colour together per car event | More complete and accurate records |
• Better data consistency (plate matches colour)
• More efficient handling of each event
• Less risk of missing information
Key Point
| Concept | Meaning | Example |
|---|---|---|
| Concurrent processing | Several tasks are in progress at the same time: one starts before another has finished | A browser, a music player and an update all running |
| On a single core | The processor gives each task a slice of time in turn, so they appear to run together | Three tasks sharing one core |
| On several cores | Different tasks run on different cores at the same instant (parallel processing) | One task on each core |
| Everyday concurrency pattern | Multiple active activities with shared resources/time | Cooking multiple dishes, supermarket checkout lanes |
Identifying the Parts of a Problem That Can Run at the Same Time
Definition
Two parts of a problem can be tackled concurrently when neither needs the result of the other. A part that depends on the output of another has to wait for it, so those parts must stay in sequence.
Worked Example
Worked Example: Loading a Web Page
Method: decompose the problem into tasks, note what each task needs before it can start, then group the tasks that do not depend on each other.
| Task | Depends on | Can it run concurrently? |
|---|---|---|
| Download the HTML file | Nothing | It must come first, because it lists the other files needed |
| Download image 1 | The HTML file | Yes, alongside the other downloads |
| Download image 2 | The HTML file | Yes, alongside the other downloads |
| Download the style sheet | The HTML file | Yes, alongside the images |
| Display the finished page | All of the downloads | No: it must wait until the others have finished |