[SessionState(SessionStateBehavior.Required)]
public class FlightController : AsyncController {

[DisableBrowserCache]
public void ListAsync() {
//取Session 能取出来
ProductInfo pinfo = SessionHelper.Get<SessionKeys , ProductInfo>(SessionKeys.ProductInfo);

AsyncManager.OutstandingOperations.Increment();
Task.Factory.StartNew(() => {
var flights = Enumerable.Empty<PKGRoutingOnlineViewModel>();
if(pinfo != null)
/////////////
flights = pinfo.AvaliableFlights.Value;
/////////////
AsyncManager.Parameters["flights"] = flights;
AsyncManager.Parameters["pInfo"] = pinfo;
AsyncManager.OutstandingOperations.Decrement();
});
}

public ActionResult ListCompleted(IEnumerable<PKGRoutingOnlineViewModel> flights, ProductInfo pInfo) {
//将整个 pInfo 保存到 Session里
SessionHelper.Set<SessionKeys>(SessionKeys.ProductInfo , pInfo);
...

/////整个问题就是围绕着这个变量.
private List<PKGRoutingOnlineViewModel> avaliableFlights = null;
/// <summary>
/// 可用机票
/// </summary>
/// <returns></returns>
public Lazy<List<PKGRoutingOnlineViewModel>> AvaliableFlights {
get {
return new Lazy<List<PKGRoutingOnlineViewModel>>(() => {
///////////////////
if(this.avaliableFlights == null) {
///////////////////
Debug.Print("avaliableFlights is null");
using(var client = new FlightServiceClient()) {
var routings = this.FlightResources.Select(r => r.ResourceID).ToList();
this.avaliableFlights = client.QueryFlightByRoutings(routings , DateTime.Now.AddDays(20) , DateTime.Now.AddDays(25) , this.AdultQty , this.ChildQty) ?? new List<PKGRoutingOnlineViewModel>();
}
} else {
Debug.Print("avaliableFlights is not null");
}
return this.avaliableFlights;
});
}
}

o.GetFlight = function(){
$.get(SITEROOT + "/Flight/List", $.proxy(fillFlight));
}

var fillFlight = function(result){
$("#flight").html(result);
$("#flightTabs").tabs();
}