IntermediateTopic 42 of 104Software & Computing
Concurrency and threads
Run tasks simultaneously; need care with shared state.
In depth
Threads let a program run tasks concurrently within a process sharing memory; processes are isolated. Concurrency improves responsiveness and throughput on multicore CPUs. Synchronisation (locks, atomics) protects shared data; thread pools bound resource use. GIL in CPython limits CPU-bound parallel threads.
Key points
- Parallel vs concurrent
- Context switching cost
- Futures and tasks
ExampleA web server handles each request in a worker thread.
What is Concurrency and threads?
Run tasks simultaneously; need care with shared state.
Why is it important to understand concurrency and threads?
Concurrency lets programs do several things at once, which speeds up work and keeps interfaces responsive.
What is the difference between concurrency and parallelism?
Concurrency is structuring a program to handle many tasks, while parallelism runs tasks at the same time on several cores.
Why is shared state dangerous?
Two threads can change the same data at once, which causes errors that depend on timing and are hard to reproduce.
How is Concurrency and threads used in practice?
Typical applications include processing sensor data in one thread while another handles the user interface, downloading several files at the same time and running independent simulation cases in parallel on a multicore machine.
What should I learn before Concurrency and threads?
Study "Pointers and references" first (topic 41 of 104 in Software & Computing). It covers the groundwork this topic builds on.
What are the key points of Concurrency and threads?
Parallel vs concurrent. Context switching cost. Futures and tasks.
Can you give an example of Concurrency and threads?
A web server handles each request in a worker thread.
What comes after Concurrency and threads?
The next topic is "Race conditions and deadlocks", which builds directly on this one.
How difficult is Concurrency and threads?
It is classed as Intermediate in Software & Computing (topic 42 of 104). It is an intermediate topic. Work through the beginner topics in Software & Computing first.