Laravel 4 如何使用ajax（get）设置最大执行时间

当我检索大量数据时，会出现错误“500 Internal Server error”。当我选择一个只有10个城市的国家时，它会起作用，但当我选择一个有10万个城市的国家时，就会出现错误。有什么解决办法吗

我的剧本

$('#country_id').on('change',function(e){
  console.log(e);
    var cat_id = e.target.value;
    var e = document.getElementById("country_id");
    var str = e.options[e.selectedIndex].value;
    document.getElementById('txt').value = str;

  $.get('/public/countrycity/ajax-sub?cat_id=' + cat_id, function(data){
          $('#state').empty(); 
    $.each(data, function(category, subcatObj){
      $('#state').append('<option value="'+subcatObj.id+'">'+subcatObj.FULL_NAME_ND+'</option>'); 

    });
  });

});

$('#state').on('change',function(e){
  console.log(e);
    var e = document.getElementById("state");
    var strs = e.options[e.selectedIndex].value;
    document.getElementById('txts').value = strs;
});

---

请发布您尝试过的代码。这是代码@chxzy

public function getCountry()
{
    $countries = Country::all();
    $cat_id = Input::get('cat_id');
    $cities = City::where('id', '=', $cat_id)->get();
    return View::make('countrycity.countrycity')
        ->with('countries',$countries)
            ->with('cities',$cities)
                ->with('title', 'Ajax');
}

public function getCity()
{
    $cat_id = Input::get('cat_id');

    $cities = City::where('CC_FIPS', '=', $cat_id)->get();
    return Response::json($cities);
}