Added the memory monitoring test.

tests/manual/memory-monitor.js

@@ -0,0 +1,84 @@
+'use strict';
+
+const RE2 = require('../../re2');
+
+const N = 5_000_000;
+
+console.log('Never-ending loop: exit with Ctrl+C.');
+
+const aCharCode = 'a'.charCodeAt(0);
+const randomAlpha = () => String.fromCharCode(aCharCode + Math.floor(Math.random() * 26));
+
+const humanizeNumber = n => {
+	const negative = n < 0;
+	if (negative) n = -n;
+
+	const s = n.toFixed();
+	let group1 = s.length % 3;
+	if (!group1) group1 = 3;
+
+	let result = s.substring(0, group1);
+	for (let i = group1; i < s.length; i += 3) {
+		result += ',' + s.substring(i, i + 3);
+	}
+
+	return (negative ? '-' : '') + result;
+};
+
+const CSI = '\x1B[';
+const cursorUp = (n = 1) => CSI + (n > 1 ? n.toFixed() : '') + 'A';
+const sgr = (cmd = '') => CSI + (Array.isArray(cmd) ? cmd.join(';') : cmd) + 'm';
+const RESET = sgr();
+const NOTE = sgr(91);
+
+let first = true;
+const maxMemory = {heapTotal: 0, heapUsed: 0, external: 0, arrayBuffers: 0, rss: 0},
+	labels = {
+		heapTotal: 'heap total',
+		heapUsed: 'heap used',
+		external: 'external',
+		arrayBuffers: 'array buffers',
+		rss: 'resident set size'
+	},
+	maxLabelSize = Math.max(...Array.from(Object.values(labels)).map(label => label.length));
+
+const report = () => {
+	const memoryUsage = process.memoryUsage(),
+		previousMax = {...maxMemory};
+
+	console.log((first ? '' : '\r' + cursorUp(6)) +
+	            ''.padStart(maxLabelSize + 1), 'Current'.padStart(15), 'Max'.padStart(15));
+  for (const name in maxMemory) {
+  	const prefix = previousMax[name] && previousMax[name] < memoryUsage[name] ? NOTE : RESET;
+  	console.log(
+  		(labels[name] + ':').padStart(maxLabelSize + 1),
+  		prefix + humanizeNumber(memoryUsage[name]).padStart(15) + RESET,
+  		humanizeNumber(maxMemory[name]).padStart(15)
+  	);
+  }
+
+	for (const [name, value] of Object.entries(maxMemory)) {
+		maxMemory[name] = Math.max(value, memoryUsage[name]);
+	}
+
+	first = false;
+}
+
+for (;;) {
+	const re2 = new RE2(randomAlpha(), 'g');
+
+	let s = '';
+	for (let i = 0; i < N; ++i) s += randomAlpha();
+
+	let n = 0;
+	for (const _ of s.matchAll(re2)) ++n;
+
+	re2.lastIndex = 0;
+	const r = s.replace(re2, '');
+	if (r.length + n != s.length) {
+		console.log('ERROR!', 's:', s.length, 'r:', r.length, 'n:', n, 're2:', re2.toString());
+		break;
+	}
+
+	report();
+}