c# - Entity Framework - 同时执行多个查询时出错

Question

在我的应用程序中同时发生了两件事。计时器每隔几秒在后台线程中触发更新数据网格的请求。这是该线程运行的代码:

    // Query
    var qryPickupRequests = from pr in objDataContext.pickupRequests
                                .Include("toLocation")
                                .Include("fromLocation")
                                .Include("person")
                            orderby pr.creationDate ascending
                            select pr;

    // Refresh from server?
    if (boolRefreshFromServer)
        (qryPickupRequests as ObjectQuery).MergeOption = MergeOption.PreserveChanges;

    // Limit?
    if (intLimit > 0)
        return qryPickupRequests.Take(intLimit).ToList<pickupRequest>();
    else
        return qryPickupRequests.ToList<pickupRequest>();

现在，在 UI 线程中，打开了另一个正在更新位置网格的表单:

/// <summary>
/// Refreshes the specified location data grid
/// </summary>
/// <param name="sender">Instance of GridLookupEdit to update</param>
private static void RefreshLocations(object sender) {

    GridLookUpEdit objEditor = sender as GridLookUpEdit;

    objEditor.Properties.DataSource = BRData.Models.LocationModel.GetLocationList(true);
    objEditor.Properties.DisplayMember = "locationName";
    objEditor.Properties.ValueMember = "locationID";

}

我遇到的问题是这两个代码块是同时执行的。我收到以下错误:

内部异常如下:

There is already an open DataReader associated with this Connection which must be closed first.

为什么并发数据库操作不能被 Entity Framework 或我正确处理，有什么想法吗？

Answer 1

Entity Framework 对象上下文不是线程安全的。确保你使用的上下文与你使用的每个线程不同——从你的示例代码中看不出你这样做，但这将是我对问题出在哪里的第一个猜测。