- [1.6] Processes/threads implement concurrent tasks. They can communicate using shared memory (threads) or using system calls (processes).
- [1.7] Advantages include speed, more intuitive design for multi-task systems, and taking advantage of distributed computing.
- Some definitions are:
- [1.7] Structures
- Data-parallel: do same thing on different parts of data.
- Task-parallel: do different things.
- [1.27] Atomic actions cannot be interrupted.
- Actions are independent if reversing their order has no effect.
- [1.33] Correctness properties
- Safety: system satisfies invariant after every action (being correct).
- Liveness: system does something useful overall.
- Performance properties
- Latency: requests are serviced quickly.
- Throughput: high number of requests processed overall.
- [4.10] Fairness means no request/event is starved.
- Equable if all equally served.
- [2.30] Happens-before preorder (refl. & trans.) \(\preceq\).
- [1.7] Structures
- [1.25, 3.52] CSO basics
proc { ... } // process
run(p: PROC) // run process
p.fork // run in parallel to current thread
p || q // parallel composition
|| (for (...) yield proc { ...})
exit() // stop thread pool