Account for memory and disk usage — Connect the previous skills

PART I

Warm-up

Reconnect with a useful idea before starting account for memory and disk usage. In one or two sentences, describe the input, output or host boundary from the previous exercise that this lesson builds on. If you are arriving directly, skim the worked example first; there is no locked prerequisite.

A rough note is enough. You can revise it after the example.

PART II

Instruction & guided example

Connect stale samples to admission

A budget dashboard must state what is counted, when it was measured and which limit applies. Memory and disk are different resources: free disk cannot satisfy an exhausted memory allocation. Separate live usage, reservations and estimated future work so the display does not promise capacity that has already been committed.

Exercise host contract: memory budget is 64 MiB and disk budget 200 MiB. Preview buffers use 24 MiB memory; an active transform reserves 16 MiB memory; report files use 90 MiB disk; a pending export reserves 40 MiB disk. Counts include the stated workload only; runtime overhead, sampling accuracy and atomic reservations require host documentation.

Supplied case: Dashboard sampled 24 MiB unreserved memory at 10:00:00. Another job reserves 12 at 10:00:01 before a 20 MiB request.

Worked reasoning: At admission time only 12 MiB remains, so the new 20 MiB request must be refused/deferred even if the screen still shows 24. A timestamped sample describes past observation; authoritative reservation checks govern current admission.

Contrast and diagnosis: Using the visible chart as the allocator creates a race between sampling and commitment.

Worked reasoning and supplied artifact

// Disposable exercise fixture / host-contract notes; not executable API syntax.
// Supplied input: Dashboard sampled 24 MiB unreserved memory at 10:00:00. Another job reserves 12 at 10:00:01 before a 20 MiB request.
// Worked prediction: At admission time only 12 MiB remains, so the new 20 MiB request must be refused/deferred even if the screen still shows 24. A timestamped sample describes past observation; authoritative reservation checks govern current admission.
// Rejected alternative: Using the visible chart as the allocator creates a race between sampling and commitment.

Illustrative example from the proposed WillowScript design. The language and WUIX/WMATH/WDB/WAUDIO/WTMP services are not implemented in the supplied source. This site has no interpreter, VM or native host and does not execute or certify the snippet.

Try the guided change

Reconstruct the supplied worked case first: list its inputs, intermediate decisions and final artifact. Compare each row with the explanation and identify exactly where the rejected alternative fails. Then use the changed inputs in Part IV for independent work.

• Write the supplied inputs and initial state before following the example.
• Reconstruct each intermediate calculation or host decision, then compare with the worked artifact.
• Explain why the contrasting alternative fails before attempting the changed inputs in Part IV.

PART III

Take a breather

Step back after the guided example. Look away from the screen, stretch, or reread your prediction. This is an optional learning pause, not a timer or an assessment gate.

When you return, try to name the lesson’s key idea without copying its wording. If that feels difficult, return to Part II and trace one line rather than restarting the entire lesson.

PART IV

Independent practice

Project context: Resource budget dashboard. Build a small, understandable change around account for memory and disk usage.

Draw the sample→reserve 12→request 20 timeline. Write displayed estimate and actual admission state as separate columns.

What to produce

Draw the sample→reserve 12→request 20 timeline. Write displayed estimate and actual admission state as separate columns. Include input → intermediate decision/state → predicted outcome, with any required host rule stated explicitly.

• State the intended behavior in a sentence before editing.
• Use only source-backed syntax and the host services whose contract you have been given.
• Record a normal case and a boundary or unavailable-resource case.
• Label hand predictions separately from anything actually measured in a supplied toolchain.

Syntax colors are a reading aid, not a compiler. The line you are editing stays uncolored until you move to a different line; capitalization is never changed. Drafts stay on this browser and code is not executed.

import tmp;
const cache = tmp.create({
    name: "report-cache",
    storage: "ssd",
    maxSize: "2GB",
    lifetime: { duration: "30m", refreshOnAccess: true },
    cleanup: { automatic: true, onCrashRecovery: true }
});

PART V

Self-check

Use this check to notice what to revisit. It does not award a private course grade, block another page or claim to verify compiled code. Every answer has a learning explanation.

You may keep exploring even if you are unsure. Use the hint, compare the trace, and revise your explanation.

PART VI

Recap & small task

Bring the idea back to the mod feature you are building. A useful recap connects the mechanism to a decision you can make in your own code.

• Connect stale samples to admission
• Explain the decision for the supplied case, then independently work the changed fixture.
• Separate source-backed behavior, host requirements and untested predictions.

One small recap task

In one or two sentences, name the decisive rule in “Connect stale samples to admission” and predict the outcome of one changed input from your independent fixture. State which host behavior still needs real verification.

This marks your personal practice record only. It is not a certification or an official workspace assessment.