src/vs/workbench/contrib/performance/electron-sandbox/startupTimings.ts/StartupTimings/_appendStartupTimes
class StartupTimings:	private async _appendStartupTimes(standardStartupError: string | undefined) {
		const appendTo = this._environmentService.args['prof-append-timers'];
		if (!appendTo) {
			// nothing to do
			return;
		}

		const { sessionId } = await this._telemetryService.getTelemetryInfo();

		Promise.all([
			this._timerService.whenReady(),
			timeout(15000), // wait: cached data creation, telemetry sending
		]).then(async () => {
			const uri = URI.file(appendTo);
			const chunks: VSBuffer[] = [];
			if (await this._fileService.exists(uri)) {
				chunks.push((await this._fileService.readFile(uri)).value);
			}
			chunks.push(VSBuffer.fromString(`${this._timerService.startupMetrics.ellapsed}\t${this._productService.nameShort}\t${(this._productService.commit || '').slice(0, 10) || '0000000000'}\t${sessionId}\t${standardStartupError === undefined ? 'standard_start' : 'NO_standard_start : ' + standardStartupError}\n`));
			await this._fileService.writeFile(uri, VSBuffer.concat(chunks));
		}).then(() => {
			this._nativeHostService.exit(0);
		}).catch(err => {
			console.error(err);
			this._nativeHostService.exit(0);
		});
	}