I build backends that have to stay up.

// matchmaking: one actor per queue, players arrive as messages
public class MatchmakingActor extends AbstractBehavior<Command> {
  private final Deque<Player> queue = new ArrayDeque<>();
  private static final int TEAM_SIZE = 5;

  Behavior<Command> onJoin(Join msg) {
    queue.add(msg.player);
    if (queue.size() >= TEAM_SIZE * 2) startMatch();
    return this;
  }
}

// device service: retry with backoff before giving up on a phone
func (s *DeviceServer) Install(ctx context.Context, req *pb.InstallRequest) (*pb.InstallReply, error) {
  for attempt := 1; attempt <= 3; attempt++ {
    if err := s.push(ctx, req.Udid, req.Ipa); err == nil {
      return &pb.InstallReply{Ok: true}, nil
    }
    time.Sleep(time.Duration(attempt) * time.Second)
  }
  return nil, status.Error(codes.Unavailable, "device not responding")
}

# agent loop: plan from the knowledge base, act, verify
async def run(goal: str, device: Device) -> Result:
    steps = await kb.plan(goal, app=device.app)
    for step in steps:
        el = await find(device, step.target)  # xml first, image match second
        await device.tap(el)
    return await verify(device, goal)

// matchmaking: one actor per queue, players arrive as messages
public class MatchmakingActor extends AbstractBehavior<Command> {
  private final Deque<Player> queue = new ArrayDeque<>();
  private static final int TEAM_SIZE = 5;

  Behavior<Command> onJoin(Join msg) {
    queue.add(msg.player);
    if (queue.size() >= TEAM_SIZE * 2) startMatch();
    return this;
  }
}

// device service: retry with backoff before giving up on a phone
func (s *DeviceServer) Install(ctx context.Context, req *pb.InstallRequest) (*pb.InstallReply, error) {
  for attempt := 1; attempt <= 3; attempt++ {
    if err := s.push(ctx, req.Udid, req.Ipa); err == nil {
      return &pb.InstallReply{Ok: true}, nil
    }
    time.Sleep(time.Duration(attempt) * time.Second)
  }
  return nil, status.Error(codes.Unavailable, "device not responding")
}

# agent loop: plan from the knowledge base, act, verify
async def run(goal: str, device: Device) -> Result:
    steps = await kb.plan(goal, app=device.app)
    for step in steps:
        el = await find(device, step.target)  # xml first, image match second
        await device.tap(el)
    return await verify(device, goal)