What is the difference between a thread and a process?
Asked first in almost every concurrency round, and treated as a warm-up by candidates who then answer it in terms of speed rather than memory. The whole answer turns on what is shared.
Exam
Answer these to pass this module.
Start here rather than at the reading. Whatever you miss tells you which part of Learn you actually need — and anything you get right is a part you can skip.
One thread in a process dereferences a null pointer and the process receives SIGSEGV. What happens to the other threads?
Which of these is NOT shared between two threads of the same process?
Why is a context switch between two threads of one process cheaper than between two processes?
Explain mode
What is the difference between a thread and a process?
Answer without using the word "lightweight". If you can explain it in terms of what is and is not shared, you understand it.
Your own words, two or three sentences, nothing looked up. The rubric unlocks once you submit.
Graded against a set rubric. Three a day on a free account. Need more? Ask on our Facebook page — it's free.
Learn
Address spaces, what a process owns versus what its threads share, the cost of creating and switching each, how they communicate, and why one bad thread takes the whole process with it.
Ask an AI to teach you this
I'm preparing for a quant developer interview on "What is the difference between a thread and a process?" Concepts I need to own: address spaces, what a process owns versus what its threads share, the cost of creating and switching each, how they communicate, and why one bad thread takes the whole process with it. Run this as interview practice, not a lecture. One concept at a time. Wait for my answer before moving on. Per concept: 1. Teach it. Lead with the one-line core claim, then a few short paragraphs. Assume I write C++ but have never had this explained properly. No jargon without defining it. 2. "The 60-second version" — what a strong candidate would SAY out loud. First person, spoken register, no bullets, no headers. That's what I'm rehearsing. 3. Ask me one question that exposes whether I only think I understood it. When I answer, reply in exactly this shape: Verdict: correct / partly correct / wrong — one line on what's wrong. What you missed: only if something's missing. 2-3 sentences. Vocabulary: only if I used a wrong or vague term. Give the right one. Example answer: the model spoken answer, 30 seconds max, first person. More info: define any term I probably don't know, one line each. Follow-up probe: the one question an interviewer asks someone who gave that model answer. Skip any section that doesn't apply. Don't pad. If I'm wrong, say wrong — don't soften it. Do not write my implementation for me. If I ask, refuse and ask what I'd try instead — I need to defend this code with the editor closed.
Do
Ship
Practice with AI
Use these to make the AI your examiner, not your author. If the AI wrote the code, this node doesn't count — you can't defend a design you didn't make.
- P8 — grade my explanation against the rubric, and name what I left out
- P1 — Socratic tutor (refuses to write code)