anchor.diff:      final DateTime beforeSpawn = DateTime.now();
       await Isolate.spawn(
           isolateCompiler,
  -        StartMessageLatencyAndMemory(
  -            receivePort.sendPort, beforeSpawn, ProcessInfo.currentRss),
  +        StartMessageLatencyAndMemory(receivePort.sendPort, beforeSpawn,
  +            await currentHeapUsage(wsUri, groupRefId), wsUri, groupRefId),
           onExit: onExitReceivePort.sendPort,
           onError: onExitReceivePort.sendPort);
       final DateTime afterSpawn = DateTime.now();
  
positive.code: // BSD-style license that can be found in the LICENSE file.
  
  import 'dart:async';
  import 'dart:io';
  import 'dart:isolate';
  import 'dart:math';
  
  import 'package:meta/meta.dart';
  
  import 'package:compiler/src/dart2js.dart' as dart2js_main;
  
  class SpawnLatencyAndMemory {
    SpawnLatencyAndMemory(this.name);
  
    Future<ResultMessageLatencyAndMemory> run() async {
      final completerResult = Completer();
  
negative.code:     this.toStartRunningCodeUs,
      this.toFinishRunningCodeUs,
      this.toExitUs,
      this.deltaHeap,
    );
  
    String toString() => """$toAfterIsolateSpawnUs
  $toStartRunningCodeUs
  $toFinishRunningCodeUs
  $toExitUs
  $deltaHeap""";
  
    final Metric toAfterIsolateSpawnUs;
    final Metric toStartRunningCodeUs;
    final Metric toFinishRunningCodeUs;
    final Metric toExitUs;
    final Metric deltaHeap;
  }
  
  Future<void> isolateCompiler(StartMessageLatencyAndMemory start) async {
  