benchmark: improve process.env benchmarks

Benchmark different types of operations and make results comparable
by normalizing process.env for enumeartion.

PR-URL: https://github.com/nodejs/node/pull/29188
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>

benchmark/process/bench-env.js

@@ -3,15 +3,55 @@
 const common = require('../common');
 
 const bench = common.createBenchmark(main, {
-  n: [1e5],
+  n: [1e6],
+  operation: ['get', 'set', 'enumerate', 'query', 'delete']
 });
 
 
-function main({ n }) {
-  bench.start();
-  for (var i = 0; i < n; i++) {
-    // Access every item in object to process values.
-    Object.keys(process.env);
+function main({ n, operation }) {
+  switch (operation) {
+    case 'get':
+      bench.start();
+      for (let i = 0; i < n; i++) {
+        process.env.PATH;
+      }
+      bench.end(n);
+      break;
+    case 'set':
+      bench.start();
+      for (let i = 0; i < n; i++) {
+        process.env.DUMMY = 'hello, world';
+      }
+      bench.end(n);
+      break;
+    case 'enumerate':
+      // First, normalize process.env so that benchmark results are comparable.
+      for (const key of Object.keys(process.env))
+        delete process.env[key];
+      for (let i = 0; i < 64; i++)
+        process.env[Math.random()] = Math.random();
+
+      n /= 10;  // Enumeration is comparatively heavy.
+      bench.start();
+      for (let i = 0; i < n; i++) {
+        // Access every item in object to process values.
+        Object.keys(process.env);
+      }
+      bench.end(n);
+      break;
+    case 'query':
+      bench.start();
+      for (let i = 0; i < n; i++) {
+        'PATH' in process.env;
+      }
+      bench.end(n);
+      break;
+    case 'delete':
+      bench.start();
+      for (let i = 0; i < n; i++) {
+        delete process.env.DUMMY;
+      }
+      bench.end(n);
+      break;
   }
-  bench.end(n);
 }

test/benchmark/test-benchmark-process.js

@@ -7,5 +7,6 @@ const runBenchmark = require('../common/benchmark');
 runBenchmark('process',
              [
                'n=1',
-               'type=raw'
+               'type=raw',
+               'operation=enumerate',
              ], { NODEJS_BENCHMARK_ZERO_ALLOWED: 1 });