fix: distinguish idle from program time

ts/src/profilers/time-profiler.ts

@@ -35,10 +35,20 @@ export class TimeProfiler {
  * @param durationMillis - time in milliseconds for which to collect profile.
  */
  async profile(durationMillis: number): Promise<perftools.profiles.IProfile> {
+ // Node.js contains an undocumented API for reporting idle status to V8.
+ // This lets the profiler distinguish idle time from time spent in native
+ // code. Ideally this should be default behavior. Until then, use the
+ // undocumented API.
+ // See https://github.com/nodejs/node/issues/19009#issuecomment-403161559.
+ // tslint:disable-next-line no-any
+ (process as any)._startProfilerIdleNotifier();
  const runName = 'stackdriver-profiler-' + Date.now() + '-' + Math.random();
  profiler.startProfiling(runName);
  await delay(durationMillis);
  const result = profiler.stopProfiling(runName);
- return serializeTimeProfile(result, this.intervalMicros);
+ // tslint:disable-next-line no-any
+ (process as any)._stopProfilerIdleNotifier();
+ const profile = serializeTimeProfile(result, this.intervalMicros);
+ return profile;
  }
 }

ts/test/test-time-profiler.ts

@@ -27,6 +27,17 @@ const v8TimeProfiler = require('bindings')('time_profiler');
 
 describe('TimeProfiler', () => {
  describe('profile', () => {
+ it('should detect idle time', async () => {
+ const durationMillis = 500;
+ const intervalMicros = 1000;
+ const profiler = new TimeProfiler(intervalMicros);
+ const profile = await profiler.profile(durationMillis);
+ assert.ok(profile.stringTable);
+ assert.notStrictEqual(profile.stringTable!.indexOf('(idle)'), -1);
+ });
+ });
+
+ describe('profile (w/ stubs)', () => {
  const sinonStubs: sinon.SinonStub[] = new Array();
  before(() => {
  sinonStubs.push(sinon.stub(v8TimeProfiler, 'startProfiling'));