Video lesson: Heap Allocation and Garbage Collection

Lesson promise

By the end, the learner should be able to explain the core model for heap allocation and garbage collection, apply it to a concrete input, and identify when its usual shortcut or guarantee stops applying. This is a recording brief; publish it as a playable lesson after the narration and visual sequence have been produced and reviewed.

Narration draft

The heap holds objects whose lifetimes are not tied to one simple lexical scope. A runtime allocator reserves space, initializes an object, and returns a reference. Garbage collection reclaims memory that is no longer reachable under the collector’s object graph and root rules.

A tracing collector starts from roots such as active stacks and global references, follows pointers, and marks reachable objects. A copying collector can move live objects into a new region and update references, while a generational collector uses the observation that many objects die young to focus collection work.

Garbage collection does not prevent leaks when the program keeps unnecessary references reachable. Collection pauses, write barriers, fragmentation, and allocation rate affect latency. Manual memory management avoids some runtime work but transfers lifetime and aliasing correctness to the programmer.

Visual sequence

1. Put the input and assumptions on screen. Ask the learner to predict the next state before revealing it.
2. Animate the representation and show the operation one transition at a time.
3. Pause at the boundary case in the companion article and compare the result with the invariant.
4. End with the exercise prompt: A cache retains every response forever in a global map. Explain why the collector cannot reclaim those entries and propose a retention policy that bounds memory by behavior rather than hope.

Companion material

Use the article, trace, and interactive concept flow as the learner’s written and visual references. The video remains planned until an actual playable media URL and reviewed transcript are available.