outputcache removing items at random?

Question

I'm currently using the OutputCacheAttribute (in System.Web.Mvc) on an action:

[ChildActionOnly]
[OutputCache(Duration = 24 * 60 * 60)] // Cache for 24 hours
public ContentResult Render(string json, string pagePublished)
{

After the first page load it caches the output and holds it. It sometimes stays cached for hours, sometimes minutes.

I use this action on multiple pages, so first I thought it might have something to do with that. But I've tried to just cache one page and see if it holds, it does not. I've tried to cache a lot of pages and it sometimes holds for hours.

Anyone have an idea about what could be wrong?

EDIT:

The w3wp process uses huge amounts of RAM (this is by design and not a problem) there are still free RAM (about 5gb) for it to allocate. I have built another action that gets the current size of the httpcontext cache. This amounts to about 1350000 bytes. So there should not be a problem with memory.

I also have a problem with MemoryCache which also evicts items at random (Amounts to about 8530000 bytes.)

EDIT2:

It seems like it's saving the output from the action in both MemoryCache and httpcontext cache.

I have edited your title. Please see, "[Should questions include “tags” in their titles?](http://meta.stackexchange.com/questions/19190/)", where the consensus is "no, they should not". — John Saunders, Jan 09 '13 at 12:35
@DaveHillier The cache takes 8 mb, so there should be plenty of more space for it to use. It should evict the entry after duration has run out. — slinzerthegod, Jan 09 '13 at 12:42
Is this a dev machine and are you re-compiling? As that would cause the app pool to be recycled, which might clear the cache. — Chris Chilvers, Jan 09 '13 at 12:46

score 0 · Answer 1 · answered Jan 09 '13 at 12:44

0

There is no guarantee that content will be cached for the amount of time that you specify. When memory resources become low, the cache starts evicting content automatically.

answered Jan 09 '13 at 12:44

James

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Free memory is not a problem. – slinzerthegod Jan 09 '13 at 16:17
@slinzerthegod Point being, the `duration` property is not set in stone, treat it more of a *recommended* cache time. – James Jan 09 '13 at 16:30
If there is 5GB of free memory on the server it shouldn't be a problem? – slinzerthegod Jan 09 '13 at 16:40
I would have thought so, you don't appear to be setting the `Location` property of your cache therefore it could be stored anywhere (client/server/proxy server etc.). Obviously, different locations have different effects on what causes the cache to clear. Try switching it to `OutputCacheLocation.Server` and see if it lasts the specified duration (I assume it will). – James Jan 09 '13 at 18:04
You can't set Location for a ChildAction. As you can see here: http://stackoverflow.com/questions/6410431/outputcache-attribute-on-clientside-with-partial-pages – slinzerthegod Jan 10 '13 at 08:38

outputcache removing items at random?

1 Answers1