如何避免缓存服务通道工厂时出现服务通道泄漏

目前，我缓存ServiceChannelFactory并在每次需要时创建一个新ServiceChannel。我希望ServiceChannels由垃圾收集器处理。但是，工厂会保留对每个通道的引用，以便在您调用ServiceFactoryChannel.Close()时可以关闭该通道。这导致许多旧频道一直活跃到一切都停止工作的地步。

如何缓存工厂并仍然让垃圾回收器处理我的通道？

我的代码如下所示：

public class ServiceChannel
{
    // Returns a ServiceChannel
    public static TService Get<TService>()
    {
        var factory = GetChannelFactory<TService>();
        string url = GetEndpoint<TService>();
        var endPoint = new EndpointAddress(url);
        return factory.CreateChannel(endPoint);
    }
    // Returns a ServiceChannelFactory, preferably from the cache
    public static ChannelFactory<TService> GetChannelFactory<TService>()
    {
        var cacheKey = string.Format("MyProduct.Library.ServiceChannel.GetChannelFactory<{0}>()", typeof(TService));
        var cache = HttpRuntime.Cache;
        var factory = cache[cacheKey] as ChannelFactory<TService>;
        if (factory == null)
        {
            factory = GetChannelFactoryUncached<TService>();
            cache.Insert(cacheKey, factory);
        }
        return factory;
    }
}