| 1 | import { mkdirSync, writeFileSync } from "node:fs"; |
| 2 | import path from "node:path"; |
| 3 | import { describe, expect, it, vi } from "vitest"; |
| 4 | import { BUSY_BUCKETS } from "@diffinery/shared"; |
| 5 | import { UsageSampler, describeUsage, saturatedAt } from "../src/usage.js"; |
| 6 | import { tmp } from "./helpers.js"; |
| 7 | |
| 8 | /** A fake /proc: CPU ticks (busy, idle) summed over all CPUs, memory in use and an OOM kill count. */ |
| 9 | function fakeProc(dir: string) { |
| 10 | mkdirSync(dir, { recursive: true }); |
| 11 | return (busy: number, idle: number, usedMiB: number, oom = 0, totalMiB = 4096) => { |
| 12 | // user nice system idle iowait irq softirq steal: busy split over user and system; steal isn't busy. |
| 13 | writeFileSync(path.join(dir, "stat"), `cpu ${busy - 10} 0 10 ${idle} 0 0 0 7 0 0\ncpu0 1 2 3\n`); |
| 14 | writeFileSync(path.join(dir, "meminfo"), `MemTotal: ${totalMiB * 1024} kB\nMemFree: 1 kB\nMemAvailable: ${(totalMiB - usedMiB) * 1024} kB\n`); |
| 15 | writeFileSync(path.join(dir, "vmstat"), `pgfault 5\noom_kill ${oom}\n`); |
| 16 | }; |
| 17 | } |
| 18 | |
| 19 | describe("usage sampler", () => { |
| 20 | it("measures a short burst at its height with its default quarter-second windows", () => { |
| 21 | vi.useFakeTimers({ now: 0 }); |
| 22 | try { |
| 23 | for (const [windowMs, expected] of [[undefined, 1], [2000, 0.13]] as const) { |
| 24 | const proc = path.join(tmp(), "proc"); |
| 25 | const set = fakeProc(proc); |
| 26 | let busy = 10; |
| 27 | let idle = 0; |
| 28 | set(busy, idle, 500); |
| 29 | const s = new UsageSampler({ procRoot: proc, diskPath: proc, visible: 4, ...(windowMs ? { windowMs, sampleMs: 500 } : {}) }); |
| 30 | s.start(); |
| 31 | // 1.75 s idle, then a quarter second with one of four CPUs busy, then idle: 10 ms ticks. |
| 32 | for (let t = 0; t < 400; t++) { |
| 33 | const on = t >= 175 && t < 200; |
| 34 | busy += on ? 1 : 0; |
| 35 | idle += on ? 3 : 4; |
| 36 | set(busy, idle, 500); |
| 37 | vi.advanceTimersByTime(10); |
| 38 | } |
| 39 | const u = s.stop()!; |
| 40 | expect(u.coresMax).toBeCloseTo(expected, 1); |
| 41 | expect(u.windowSeconds).toBe((windowMs ?? 250) / 1000); |
| 42 | } |
| 43 | } finally { |
| 44 | vi.useRealTimers(); |
| 45 | } |
| 46 | }); |
| 47 | |
| 48 | it("measures busy cores per window, peak memory and OOM kills", () => { |
| 49 | vi.useFakeTimers({ now: 0 }); |
| 50 | try { |
| 51 | const proc = path.join(tmp(), "proc"); |
| 52 | const set = fakeProc(proc); |
| 53 | set(0, 0, 500); |
| 54 | const s = new UsageSampler({ procRoot: proc, diskPath: proc, sampleMs: 500, windowMs: 2000, visible: 4 }); |
| 55 | s.start(); |
| 56 | // First 2 s: 1 of 4 CPUs busy (busy is a quarter of all ticks). Memory peaks at 1500 MiB mid-window. |
| 57 | set(100, 300, 1500); |
| 58 | vi.advanceTimersByTime(1000); |
| 59 | set(200, 600, 800); |
| 60 | vi.advanceTimersByTime(1000); |
| 61 | // Next 2 s: all 4 busy, and one OOM kill. |
| 62 | set(1000, 600, 900, 1); |
| 63 | vi.advanceTimersByTime(2000); |
| 64 | const u = s.stop()!; |
| 65 | expect(u.seconds).toBe(4); |
| 66 | expect(u.cores).toBe(4); |
| 67 | expect(u.cpuSeconds).toBeCloseTo(10, 1); |
| 68 | expect(u.coresMax).toBe(4); |
| 69 | expect(u.memoryPeak).toBe(1500 * 1024 * 1024); |
| 70 | expect(u.memory).toBe(4096 * 1024 * 1024); |
| 71 | expect(u.oomKills).toBe(1); |
| 72 | expect(u.saturated).toBe(0.5); |
| 73 | expect(u.busySeconds).toHaveLength(BUSY_BUCKETS.length); |
| 74 | expect(u.busySeconds[BUSY_BUCKETS.indexOf(1)]).toBe(2); |
| 75 | expect(u.busySeconds[BUSY_BUCKETS.indexOf(4)]).toBe(2); |
| 76 | expect(describeUsage(u)).toBe("Resources: 2.5 of 4 vCPUs busy on average (4.0 at the 95th percentile), peak memory 1.5 GiB of 4.0 GiB, peak disk " + `${(u.diskPeak / 1e9).toFixed(1)} GB of ${(u.disk / 1e9).toFixed(1)} GB, 1 process(es) killed for want of memory`); |
| 77 | } finally { |
| 78 | vi.useRealTimers(); |
| 79 | } |
| 80 | }); |
| 81 | |
| 82 | it("counts busy cores against a fractional share of CPU", () => { |
| 83 | vi.useFakeTimers({ now: 0 }); |
| 84 | try { |
| 85 | const proc = path.join(tmp(), "proc"); |
| 86 | const set = fakeProc(proc); |
| 87 | set(0, 0, 100); |
| 88 | // One CPU visible, a quarter of it allotted: a quarter of the ticks busy is all it has. |
| 89 | const s = new UsageSampler({ procRoot: proc, diskPath: proc, windowMs: 2000, visible: 1, cores: 0.25 }); |
| 90 | s.start(); |
| 91 | set(50, 150, 100); |
| 92 | vi.advanceTimersByTime(2000); |
| 93 | const u = s.stop()!; |
| 94 | expect(u.cores).toBe(0.25); |
| 95 | expect(u.coresMax).toBe(0.25); |
| 96 | expect(u.saturated).toBe(1); |
| 97 | expect(saturatedAt(0.25)).toBeCloseTo(0.225); |
| 98 | expect(saturatedAt(4)).toBe(3.75); |
| 99 | } finally { |
| 100 | vi.useRealTimers(); |
| 101 | } |
| 102 | }); |
| 103 | |
| 104 | it("measures nothing where /proc can't be read", () => { |
| 105 | const s = new UsageSampler({ procRoot: path.join(tmp(), "missing") }); |
| 106 | s.start(); |
| 107 | expect(s.stop()).toBeNull(); |
| 108 | }); |
| 109 | }); |