780d358
@@ -21,7 +21,7 @@
test("a child writing 200 MB stays blocked while nobody reads, and memory stays
  expect(total).toBe(200 * MB);
  expect(await proc.exited).toBe(0);
  expect(process.memoryUsage.rss() - before).toBeLessThan(64 * MB);
});
}, 30_000);
test("a reader that takes one chunk and stalls holds git blocked, memory bounded", async () => {
  const before = process.memoryUsage.rss();
@@ -62,17 +62,30 @@
test("cancelling the stream tells the caller to stop the writer and closes the p
  expect(proc.signalCode).toBe("SIGKILL");
});
test("a quiet writer costs almost no CPU while the reader waits", async () => {
  const pipe = await pullPipe();
  const proc = Bun.spawn(["sleep", "2"], {
    stdin: "ignore",
    stdout: pipe.writeFd,
    stderr: "ignore",
  });
  pipe.sealed();
  const before = process.cpuUsage();
  for await (const _ of pipe.stream) void _;
  const used = process.cpuUsage(before);
  expect(await proc.exited).toBe(0);
  expect((used.user + used.system) / 1000).toBeLessThan(100);
test("a quiet writer costs almost no wakeups while the reader waits", async () => {
  // Process CPU time also counts every other thing a loaded machine runs, so
  // count what the pipe itself does: each poll of a quiet writer is one
  // Bun.sleep. Backing off to 100 ms makes that ~25 over 2 s; a busy poll
  // would make hundreds.
  const realSleep = Bun.sleep;
  let sleeps = 0;
  Bun.sleep = ((ms: Parameters<typeof Bun.sleep>[0]) => {
    sleeps++;
    return realSleep(ms);
  }) as typeof Bun.sleep;
  try {
    const pipe = await pullPipe();
    const proc = Bun.spawn(["sleep", "2"], {
      stdin: "ignore",
      stdout: pipe.writeFd,
      stderr: "ignore",
    });
    pipe.sealed();
    for await (const _ of pipe.stream) void _;
    expect(await proc.exited).toBe(0);
  } finally {
    Bun.sleep = realSleep;
  }
  expect(sleeps).toBeGreaterThan(0);
  expect(sleeps).toBeLessThan(40);
});
		@@ -21,7 +21,7 @@ test("a child writing 200 MB stays blocked while nobody reads, and memory stays
21	21	expect(total).toBe(200 * MB);
22	22	expect(await proc.exited).toBe(0);
23	23	expect(process.memoryUsage.rss() - before).toBeLessThan(64 * MB);
24		});
	24	}, 30_000);
25	25
26	26	test("a reader that takes one chunk and stalls holds git blocked, memory bounded", async () => {
27	27	const before = process.memoryUsage.rss();
		@@ -62,17 +62,30 @@ test("cancelling the stream tells the caller to stop the writer and closes the p
62	62	expect(proc.signalCode).toBe("SIGKILL");
63	63	});
64	64
65		test("a quiet writer costs almost no CPU while the reader waits", async () => {
66		const pipe = await pullPipe();
67		const proc = Bun.spawn(["sleep", "2"], {
68		stdin: "ignore",
69		stdout: pipe.writeFd,
70		stderr: "ignore",
71		});
72		pipe.sealed();
73		const before = process.cpuUsage();
74		for await (const _ of pipe.stream) void _;
75		const used = process.cpuUsage(before);
76		expect(await proc.exited).toBe(0);
77		expect((used.user + used.system) / 1000).toBeLessThan(100);
	65	test("a quiet writer costs almost no wakeups while the reader waits", async () => {
	66	// Process CPU time also counts every other thing a loaded machine runs, so
	67	// count what the pipe itself does: each poll of a quiet writer is one
	68	// Bun.sleep. Backing off to 100 ms makes that ~25 over 2 s; a busy poll
	69	// would make hundreds.
	70	const realSleep = Bun.sleep;
	71	let sleeps = 0;
	72	Bun.sleep = ((ms: Parameters<typeof Bun.sleep>[0]) => {
	73	sleeps++;
	74	return realSleep(ms);
	75	}) as typeof Bun.sleep;
	76	try {
	77	const pipe = await pullPipe();
	78	const proc = Bun.spawn(["sleep", "2"], {
	79	stdin: "ignore",
	80	stdout: pipe.writeFd,
	81	stderr: "ignore",
	82	});
	83	pipe.sealed();
	84	for await (const _ of pipe.stream) void _;
	85	expect(await proc.exited).toBe(0);
	86	} finally {
	87	Bun.sleep = realSleep;
	88	}
	89	expect(sleeps).toBeGreaterThan(0);
	90	expect(sleeps).toBeLessThan(40);
78	91	});