Lesson 081
Garbage Collection
Reachability · Ref Counting · Mark & Sweep
1:00How automatic memory managers decide what is garbage, the algorithms they use (reference counting and mark & sweep), their trade-offs, and how modern languages approach the problem.
By the end, you can
- Explain what "reachable from the roots" means and why it defines liveness.
- Trace which objects in a reference graph are garbage.
- Describe how reference counting works and identify the cycle it cannot handle.
- Explain how weak references break reference cycles.
- Describe the two phases of mark & sweep and why it reclaims cyclic garbage.
- Define stop-the-world pause and mark-compact, and state why collectors use them.
- Explain the generational hypothesis and how generational collectors exploit it.
- Identify logical memory leaks and state the fix (dropping the reference).
- Map major languages to their memory-management strategy.
Up next in Math, Memory & Files
