CacheItemRemovedCallback causes webserver to crash

Question

THis is an interesting question. I am developing a web-chat software piece and for the past couple of hours I've been trying to figure out why this happens. Basically, I add an actual chat object (the part that does communications) to the Cache collection when you start chatting. In order to detect that you closed the window, I set the sliding expiration to say 10-30 seconds. I also set the callback to let the chat client know that he needs to disconnect to end the chat session. For some odd reason, when I use the code to dispose of the chat client, whatever it is, it causes the entire w3svc process to crash (event log checked). I also tried just sending myself an email when the item is removed, which worked. I even tried to put the entire code in try-catch block but it seems to ignore that as well. Any ideas? O_o

UPD: No, i am not trying to refresh the object (in reference to this).

Adding:

HttpContext.Current.Cache.Insert("ChatClient_" + targetCid + HttpContext.Current.Session.SessionID, cl, null, Cache.NoAbsoluteExpiration,
                    TimeSpan.FromSeconds(15), CacheItemPriority.Normal, new CacheItemRemovedCallback(removeMyself));

Removing:

public static void removeMyself(string key, Object value, CacheItemRemovedReason reason) {
        var wc = (WebClient)value;
        try {
            wc.Remove();
        }
        catch { }
    }

I am in fact using the lock on HttpContext.Current.cache when adding to the cache objects.

Answer 1

Can you post both the cache.insert and item removed callbacks code? Are you using any kind of locking when inserting into the cache? Have you done anything to the default settings for the ASP.net cache? Are you able to reproduce this on another web server? Are you sure you are expiring the cache in ms instead of seconds...

Is your sliding expiration like this? TimeSpan.FromSeconds(30)