CODEWITHSUNDEEP
asp.netcaching
MalcomTucker
MalcomTucker

Reputation: 269

ASP.NET Cache - circumstances in which Remove("key") doesn't work?

I have an ASP.NET application that caches some business objects. When a new object is saved, I call remove on the key to clear the objects. The new list should be lazy loaded the next time a user requests the data.

Except there is a problem with different views of the cache in different clients.

This is a shortened version of the code:

public static JobCollection JobList
{
    get
    {
        if (HttpRuntime.Cache["JobList"] == null)
        {
                GetAndCacheJobList();
        }
        return (JobCollection)HttpRuntime.Cache["JobList"];
    }
}

private static void GetAndCacheJobList()
    {
        using (DataContext context = new DataContext(ConnectionUtil.ConnectionString))
        {
            var query = from j in context.JobEntities
                        select j;
            JobCollection c = new JobCollection();
            foreach (JobEntity i in query)
            {
                Job newJob = new Job();
                ....
                c.Add(newJob);
            }
            HttpRuntime.Cache.Insert("JobList", c, null, Cache.NoAbsoluteExpiration, Cache.NoSlidingExpiration, CacheItemPriority.Default, null);
        }
    }

public static void SaveJob(Job job, IDbConnection connection)
    {
        using (DataContext context = new DataContext(connection))
        {

               JobEntity ent = new JobEntity();
               ...
               context.JobEntities.InsertOnSubmit(ent);                
               context.SubmitChanges();
               HttpRuntime.Cache.Remove("JobList");                                     

        }
    }

Does anyone have any ideas why this might be happening?

Edit: I am using Linq2SQL to retreive the objects, though I am disposing of the context.

Upvotes: 0

Views: 777

Answers (4)

fengd
fengd

Reputation: 7569

You have to make sure that User 2 sent a new request. Maybe the content it saws is from it's browser's cache, not the cache from your server

Upvotes: 0

Neel
Neel

Reputation: 11

I would ask you to make sure you do not have multiple production servers for load balancing purpose. In that case you will have to user some external dependency architecture for invalidating/removing the cache items.

Upvotes: 1

overslacked
overslacked

Reputation: 4137

I would also check, if you haven't already, that the old data they're seeing hasn't been somehow cached in ViewState.

Upvotes: 0

user134706
user134706

Reputation: 1010

That's because you don't synchronize cache operations. You should lock on writing your List to the cache (possibly even get the list inside the lock) and on removing it from the cache also. Otherwise, even if reading and writing are synchronized, there's nothing to prevent storing the old List right after your call to Remove. Let me know if you need some code example.

Upvotes: 0

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