Refactor startup-esm-graph benchmark to create a tree-shaped graph with a branching factor of 10

Author: GeoffreyBooth

benchmark/esm/startup-esm-graph.js

@@ -7,34 +7,41 @@ const { spawnSync } = require('child_process');
 const tmpdir = require('../../test/common/tmpdir');
 
 const bench = common.createBenchmark(main, {
-  modules: [250, 500, 1000, 2000],
+  modules: ['0250', '0500', '1000', '2000'],
   n: [30],
 });
 
+const BRANCHING_FACTOR = 10;
+
 function prepare(count) {
   tmpdir.refresh();
   const dir = tmpdir.resolve('esm-graph');
   fs.mkdirSync(dir, { recursive: true });
 
-  // Create a flat ESM graph: entry imports all modules directly.
-  // Each module is independent, maximizing the number of resolve/load/link
-  // operations in the loader pipeline.
-  const imports = [];
-  for (let i = 0; i < count; i++) {
-    fs.writeFileSync(
-      path.join(dir, `mod${i}.mjs`),
-      `export const value${i} = ${i};\n`,
-    );
-    imports.push(`import './mod${i}.mjs';`);
+  // Create a tree-shaped ESM graph with a branching factor of 10.
+  // The root (mod0) plus `count` additional modules are created in BFS order.
+  // Module i imports modules BRANCHING_FACTOR*i+1 through
+  // BRANCHING_FACTOR*i+BRANCHING_FACTOR (capped at count), so the graph is a
+  // complete 10-ary tree rooted at mod0.
+  const total = count + 1;
+  for (let i = 0; i < total; i++) {
+    const children = [];
+    for (let c = 1; c <= BRANCHING_FACTOR; c++) {
+      const child = BRANCHING_FACTOR * i + c;
+      if (child < total) {
+        children.push(`import './mod${child}.mjs';`);
+      }
+    }
+    const content = children.join('\n') + (children.length ? '\n' : '') +
+      `export const value${i} = ${i};\n`;
+    fs.writeFileSync(path.join(dir, `mod${i}.mjs`), content);
   }
 
-  const entry = path.join(dir, 'entry.mjs');
-  fs.writeFileSync(entry, imports.join('\n') + '\n');
-  return entry;
+  return path.join(dir, 'mod0.mjs');
 }
 
 function main({ n, modules }) {
-  const entry = prepare(modules);
+  const entry = prepare(Number(modules));
   const cmd = process.execPath || process.argv[0];
   const warmup = 3;
   const state = { finished: -warmup };