Adds memory leak test in CI (#2616)

* Add a memory leak test

* Add memory leak smoke test to CI

* Update the latest compiler

* Update yarn.lock

* Remove entries optimization

* Calculate as 5% higher

4 files changed, 92 insertions, 0 deletions

diff --git a/scripts/memory/index.js b/scripts/memory/index.js
new file mode 100644
index 000000000..8beda6e44
--- /dev/null
+++ b/scripts/memory/index.js
@@ -0,0 +1,81 @@
+import { execa } from 'execa';
+import { fileURLToPath } from 'url';
+import v8 from 'v8';
+import dev from '../../packages/astro/dist/core/dev/index.js';
+import { loadConfig } from '../../packages/astro/dist/core/config.js';
+import prettyBytes from 'pretty-bytes';
+
+/** URL directory containing the entire project. */
+const projDir = new URL('./project/', import.meta.url);
+
+function mean(numbers) {
+	var total = 0, i;
+	for (i = 0; i < numbers.length; i += 1) {
+			total += numbers[i];
+	}
+	return total / numbers.length;
+}
+
+function median(numbers) {
+	// median of [3, 5, 4, 4, 1, 1, 2, 3] = 3
+	var median = 0, numsLen = numbers.length;
+	numbers.sort();
+
+	if (
+			numsLen % 2 === 0 // is even
+	) {
+			// average of two middle numbers
+			median = (numbers[numsLen / 2 - 1] + numbers[numsLen / 2]) / 2;
+	} else { // is odd
+			// middle number only
+			median = numbers[(numsLen - 1) / 2];
+	}
+
+	return median;
+}
+
+let config = await loadConfig({
+	cwd: fileURLToPath(projDir)
+});
+
+config.buildOptions.experimentalStaticBuild = true;
+
+const server = await dev(config, { logging: 'error'});
+
+// Prime the server so initial memory is created
+await fetch(`http://localhost:3000/page-0`);
+
+const sizes = [];
+
+function addSize() {
+	sizes.push(v8.getHeapStatistics().total_heap_size);
+}
+
+async function run() {
+	addSize();
+	for(let i = 0; i < 100; i++) {
+		let path = `/page-${i}`;
+		await fetch(`http://localhost:3000${path}`);
+	}
+	addSize();
+}
+
+for(let i = 0; i < 100; i++) {
+	await run();
+}
+
+let lastThirthy = sizes.slice(sizes.length - 30);
+let averageOfLastThirty = mean(lastThirthy);
+let medianOfAll = median(sizes);
+
+// If the trailing average is higher than the median, see if it's more than 5% higher
+if(averageOfLastThirty > medianOfAll) {
+	let percentage = Math.abs(averageOfLastThirty - medianOfAll) / medianOfAll;
+	if(percentage > .05) {
+		throw new Error(`The average towards the end (${prettyBytes(averageOfLastThirty)}) is more than 5% higher than the median of all runs (${prettyBytes(medianOfAll)}). This tells us that memory continues to grow and a leak is likely.`)
+	}
+}
+
+
+
+await server.stop();
diff --git a/scripts/memory/mk.js b/scripts/memory/mk.js
new file mode 100644
index 000000000..6e6e74637
--- /dev/null
+++ b/scripts/memory/mk.js
@@ -0,0 +1,11 @@
+import fs from 'fs';
+
+const pages = new URL('./project/src/pages/', import.meta.url);
+
+for(let i = 0; i < 100; i++) {
+	let content = `---
+const i = ${i};
+---
+<span>{i}</span>`;
+	await fs.promises.writeFile(new URL(`./page-${i}.astro`, pages), content, 'utf-8');
+}
diff --git a/scripts/memory/project/.gitkeep b/scripts/memory/project/.gitkeep
new file mode 100644
index 000000000..e69de29bb
--- /dev/null
+++ b/scripts/memory/project/.gitkeep
diff --git a/scripts/memory/project/src/pages/.gitkeep b/scripts/memory/project/src/pages/.gitkeep
new file mode 100644
index 000000000..e69de29bb
--- /dev/null
+++ b/scripts/memory/project/src/pages/.gitkeep