killProcessTree function

Future<void> killProcessTree(int pid)

Kills the process pid and every process it started, children before parents, with SIGKILL (taskkill /T /F on Windows).

Killing only the parent leaves what it spawned running: dart test starts test VMs of its own, and a hung one keeps its database connection or port. The descendants are found with pgrep -P (macOS and Linux) before any is killed, so a child that the parent's death would orphan is still reached. A process that is already gone is not an error.

Implementation

Future<void> killProcessTree(int pid) async {
  if (Platform.isWindows) {
    await Process.run('taskkill', ['/T', '/F', '/PID', '$pid']);
    return;
  }
  final all = <int>[];
  Future<void> collect(int parent) async {
    final result = await Process.run('pgrep', ['-P', '$parent']);
    for (final line in '${result.stdout}'.split('\n')) {
      final child = int.tryParse(line.trim());
      if (child == null) continue;
      await collect(child);
      all.add(child);
    }
  }

  await collect(pid);
  for (final p in [...all, pid]) {
    Process.killPid(p, ProcessSignal.sigkill);
  }
}