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From Aaron Smuts <asm...@yahoo.com>
Subject Re: Indexed Disk Cache and MaxPurgatorySize
Date Tue, 18 Aug 2009 13:47:53 GMT
Purgatory is a queue with a size limit.  If you exceed the size, by putting a very large number
of elements in faster than they can be written to disk, then the oldest will be expelled.
 They won't make it to disk, as they've been dropped from the queue.

The danger in having an unlimited queue is that you could run out of memory if there is a
tremendous spike. . . .

We need some utility for creating a disk files and then telling the disk cache to use them
 . . . 

Aaron

--- On Tue, 8/18/09, Silvano <mele@ipsoft.it> wrote:

> From: Silvano <mele@ipsoft.it>
> Subject: Indexed Disk Cache and MaxPurgatorySize
> To: "JCS Users List" <jcs-users@jakarta.apache.org>
> Date: Tuesday, August 18, 2009, 1:01 AM
> Dear All,
> 
> I'm using the Indexed Disk Cache in my application and I
> encountered some strange behavior that I try to summarize
> following.
> 
> The steps are:
> 1. I fill in the cache using a preliminary job which goal
> is to "warm-up" the cache.
> 2. When I try to retrieve the same items put in cache
> during the step one, it seems they are not in cache, or at
> least some of them are missing.
> REMARK: As you can see in the configuration chunk below,
> the elements are eternal.
> 
> I have already found a problem in the "MaxKeySize"
> parameter that was too small, but after fixing it, the
> problem is still there :-(
> 
> So my questions are:
> 1. Is it possible that the "MaxPurgatorySize" can lead to
> this kind of problem? I set it to 5000
> 2. What are the drawbacks if I set "MaxPurgatorySize" equal
> to -1 (infinite)? Is there the risk to obtain memory
> exceptions?
> 3. What are your suggestions to debug/solve the problem?
> 
> Following some details of the configuration:
> 
> # DEFAULTS
> jcs.default=DC
> jcs.default.cacheattributes=org.apache.jcs.engine.CompositeCacheAttributes
> jcs.default.cacheattributes.MaxObjects=1000
> jcs.default.cacheattributes.DiskUsagePatternName=UPDATE
> 
> # REGION
> jcs.region.Common=DC
> jcs.region.Common.cacheattributes=org.apache.jcs.engine.CompositeCacheAttributes
> jcs.region.Common.cacheattributes.MaxObjects=50
> jcs.region.Common.cacheattributes.MemoryCacheName=org.apache.jcs.engine.memory.lru.LRUMemoryCache
> jcs.region.Common.cacheattributes.UseMemoryShrinker=true
> jcs.region.Common.cacheattributes.MaxMemoryIdleTimeSeconds=30
> jcs.region.Common.cacheattributes.ShrinkerIntervalSeconds=20
> 
> jcs.region.Common.elementattributes=org.apache.jcs.engine.ElementAttributes
> jcs.region.Common.elementattributes.IsEternal=true
> 
> jcs.region.Common.elementattributes.IsSpool=true
> jcs.region.Common.elementattributes.IsRemote=false
> jcs.region.Common.elementattributes.IsLateral=true
> 
> # AUX
> jcs.auxiliary.DC=org.apache.jcs.auxiliary.disk.indexed.IndexedDiskCacheFactory
> jcs.auxiliary.DC.attributes=org.apache.jcs.auxiliary.disk.indexed.IndexedDiskCacheAttributes
> jcs.auxiliary.DC.attributes.DiskPath=/usr/local/ptt/liferay/pttCache
> jcs.auxiliary.DC.attributes.MaxPurgatorySize=5000
> jcs.auxiliary.DC.attributes.MaxKeySize=1000000
> 
> 
> If You need the full .ccf I can send you!
> 
> Thanks in advance,
>    Silvano.
> 
> 
> 
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