我需要在我的应用程序中使用跨应用程序域调用，有时我有这个 RemotingException：
对象“/2fa53226_da41_42ba_b185_ec7d9c454712/ygiw+xfegmkhdinj7g2kpkhc_7.rem”已断开连接或在服务器上不存在。
目标对象还活着，我已经检查过了。
UPD 我在目标对象的终结器中设置了断点，但它永远不会命中。因此，这个对象是存活的并且没有被 GC 处理。
【问题讨论】：
标签： c# .net clr appdomain marshalbyrefobject
这可能是因为服务器端的本地垃圾收集器收集了对象。您可以通过更新租约来防止这种情况发生。您可以在以下文章中了解更多相关信息：
更新：很遗憾，2008 年或更早的 MSDN 杂志问题不再可在线浏览，只能以 .chm 文件的形式下载到本地计算机。以前的问题可以在：
【讨论】：
这是因为服务器端的 Lifetime 管理在对象的租约到期时断开连接，以允许 GC 收集它。如果您尝试从客户端使用它，您将得到一个异常，即使它尚未在服务器上进行 GC（例如，因为仍然有另一个引用）但租约已过期。这是为了避免不可预测的行为。接受的答案为如何正确管理远程 .NET 对象的生命周期提供了很好的参考。
【讨论】：
我遇到了同样的问题，我在许多 StackOverflow 帖子的帮助下搜索了好几个小时。
我终于找到了完整的问题。
这是完整的解释和用例：
我的“Loader”类继承自 MarshalByRefObject，我通过 ISponsor 类保持它的活力。我知道 .NET 中存在“ClientSponsor”，但我无法确定是否以及何时调用 Renewal()，所以我在 StackOverflow 社区的帮助下创建了我的课程（阅读代码 cmets）：
/// <see cref="https://stackoverflow.com/questions/18680664/remoting-sponsor-stops-being-called"/>
public class RemotingSponsor : MarshalByRefObject, ISponsor, IDisposable
{
/*
* @CoryNelson said :
* I've since determined that the ILease objects of my sponsors
* themselves are being GCed. They start out with the default 5min lease
* time, which explains how often my sponsors are being called. When I
* set my InitialLeaseTime to 1min, the ILease objects are continually
* renewed due to their RenewOnCallTime being the default of 2min.
*
*/
ILease _lease;
public RemotingSponsor(MarshalByRefObject mbro)
{
_lease = (ILease)RemotingServices.GetLifetimeService(mbro);
if (_lease == null) throw new NotSupportedException("Lease instance for MarshalByRefObject is NULL");
_lease.Register(this);
}
public TimeSpan Renewal(ILease lease)
{
Debug.WriteLine("RemotingSponsor.Renewal called");
return this._lease != null ? lease.InitialLeaseTime : TimeSpan.Zero;
}
public void Dispose()
{
if (_lease != null)
{
_lease.Unregister(this);
_lease = null;
}
}
public override object InitializeLifetimeService()
{
/*
*
* @MatthewLee said:
* It's been a long time since this question was asked, but I ran into this today and after a couple hours, I figured it out.
* The 5 minutes issue is because your Sponsor which has to inherit from MarshalByRefObject also has an associated lease.
* It's created in your Client domain and your Host domain has a proxy to the reference in your Client domain.
* This expires after the default 5 minutes unless you override the InitializeLifetimeService() method in your Sponsor class or this sponsor has its own sponsor keeping it from expiring.
* Funnily enough, I overcame this by returning Null in the sponsor's InitializeLifetimeService() override to give it an infinite timespan lease, and I created my ISponsor implementation to remove that in a Host MBRO.
* Source: https://stackoverflow.com/questions/18680664/remoting-sponsor-stops-being-called
*/
return (null);
}
}
然后我像这样使用这个“自定义赞助商”：
// Loader and Container for MarshalByRefObject in another domain
public class PluginFile : IDisposable
{
private RemotingSponsor _sponsor; // Keep instance not to have Sponsor Garbage Collected
private AppDomain _sandbox;
private ICustomPlugin[] _plugins; // I do not store real instances of Plugins, but a "CustomPluginProxy" which is known both by main AppDomain and Plugin AppDomain.
// Constructor : load an assembly file in another AppDomain (sandbox)
public PluginFile(System.IO.FileInfo f, AppDomainSetup appDomainSetup, Evidence evidence)
{
Directory = System.IO.Path.GetDirectoryName(f.FullName) + @"\";
_sandbox = AppDomain.CreateDomain("sandbox_" + Guid.NewGuid(), evidence, appDomainSetup);
_sandbox.Load(typeof(Loader).Assembly.FullName);
// - Instanciate class "Loader" INSIDE OTHER APPDOMAIN, so we couldn't use new() which would create in main AppDomain.
_loader = (Loader)Activator.CreateInstance(
_sandbox,
typeof(Loader).Assembly.FullName,
typeof(Loader).FullName,
false,
BindingFlags.Public | BindingFlags.Instance,
null,
null,
null,
null).Unwrap();
// - Load plugins list for assembly
_plugins= _loader.LoadPlugins(f.FullName);
// - Keep object created in other AppDomain not to be "Garbage Collected". I create a sponsor. The sponsor in registed for object "Lease". The LeaseManager will check lease expiration, and call sponsor. Sponsor can decide to renew lease. I not renewed, the object is garbage collected.
// - Here is an explanation. Source: https://stackoverflow.com/questions/12306497/how-do-the-isponsor-and-ilease-interfaces-work
_sponsor = new RemotingSponsor(_loader);
// Here is my SOLUTION after many hours ! I had to sponsor each MarshalByRefObject (plugins) and not only the main one that contains others !!!
foreach (ICustomPlugin plugin in Plugins)
{
ILease lease = (ILease)RemotingServices.GetLifetimeService((PluginProxy)plugin);
lease.Register(_sponsor); // Use the same sponsor. Each Object lease could have as many sponsors as needed, and each sponsor could be registered in many Leases.
}
}
}
PluginProxy 类型具有对真实插件类型的引用。实际上，PluginProxy 在 Plugin AppDomain 中实例化，并返回到主 AppDomain，以允许它调用 Plugins，即使它忽略了它们的真实类型。因此，可以从主 AppDomain 访问的 PluginProxy 必须被序列化以跨越 AppDomains 限制。我遇到了问题，因为我没有赞助这些 MarshalByRefObject(s)：
/// <see cref="https://stackoverflow.com/questions/4185816/how-to-pass-an-unknown-type-between-two-net-appdomains"/>
[Serializable]
public class PluginProxy : MarshalByRefObject, ICustomPlugin
{
private ICustomPlugin _hostedPlugin;
/// <summary>
/// Parameterless constructor for deserialization
/// </summary>
public PluginProxy()
{
}
~PluginProxy()
{
Debug.WriteLine("DESTRUCTOR ~PluginProxy");
}
/// <summary>
/// Constructor reserved from real Plugin type
/// </summary>
/// <param name="name"></param>
public PluginProxy(ICustomPlugin hostedPlugin)
{
_hostedPlugin = hostedPlugin;
}
public PluginName Name => _hostedPlugin.Name;
public PluginResult Execute(PluginParameters parameters, PluginQuery query)
{
return(_hostedPlugin.Execute(parameters, query));
}
}
这是一堆难以解决的问题，希望对您有所帮助！
参考资料：
StackOverflow：Remoting sponsor stops being called
StackOverflow：How do the ISponsor and ILease interfaces work?
【讨论】：
这发生在我们身上，因为我们的一个类中有一个 AppDomain 类型的静态变量。该类用于长期运行的 Windows 服务。 AppDomain 有一个 InitializeLifetimeService 方法，需要像这样重写：
public override object InitializeLifetimeService(){
return null;
}
我们一直使用它作为私有变量，为自定义构建的外部逻辑加载和卸载一些 dll。 答案取自这里：msdn answer
因为我们无法在生产时更改此设置，我们以一种折衷的方式结束，即以比静态 AppDomain 变量的生命周期更短的随机间隔重新启动 Windows 服务，通过反复试验我们发现它是几个天。
这个问题也有助于澄清一些关于生命周期的事情：stackoverflow-question
【讨论】：
这个问题是answered in great detail already on StackOverflow。 TL/DR：
InitializeLifetimeService to return null
ClientSponsor 让您的对象存活更长时间。 【讨论】：
InitializeLifetimeService 以返回 null，因此 it 不会过期并停止响应续订请求。如果赞助商过期，远程对象最终也会过期（如果不使用单例语义）。
在我的情况下，问题是在客户端计算机中，有一个虚拟网络适配器处于活动状态，禁用虚拟网络适配器，问题就解决了
【讨论】：
在我的例子中，这发生在存储在 Web 项目内的 App_Data 文件夹中的 SQL LocalDB 上。每当我尝试使用包控制台运行update-database 以使用迁移来初始化我的实体框架数据库时，什么都没有发生。然后过了一会儿，我得到了那个错误。
我通过修改App_Data 的文件权限解决了这个问题。修复后，瞧，它起作用了。
【讨论】：