The jcs.default.cacheattributes.MaxObjects does not work as expected.

• Key: JCS-16
• Type: Bug
• Status: Open
• Priority: Minor
• Assignee: Aaron Smuts
• Reporter: Peter Lawrey
• Component/s: Composite Cache
• Affects Version/s: jcs-1.3
• Fix Version/s: jcs-1.4-dev

Description

Using code based on JSCThrashTest ..
jcs.default=
jcs.default.cacheattributes=org.apache.jcs.engine.CompositeCacheAttributes
jcs.default.cacheattributes.MaxObjects=10000
jcs.default.cacheattributes.MemoryCacheName=org.apache.jcs.engine.memory.lru.LRUMemoryCache

If I add 10,000 elements the getListSize() return 9,998 elements.
If I change the MaxObjects to 10002 and add 15 K elements the getListSize() return 10,000 elements.

Is there a good reason I need to add 2 to MaxObjects?
I have scanned the cache and found there is actually 10000 elements when MaxObject is set to 10002

Comments

[Aaron Smuts]

The memory cache is buffering items to disk when the max is reached. It's set to move 2 or 3 at once. When the max is reached, it moves 2 or 3 (I need to check).

[Juan Vaccarezza]

I inspected the code of the LRUMemoryCache and i've found that on the line 126 it checks if the max object properties has been reached, and if so, cleans the cache. I guess that this is wrong cause it has to check if the amount of stored object has exccedes the max objects configured.
Changin this lines

// If the element limit is reached, we need to spool

if ( size < this.cattr.getMaxObjects() )
{
     return;
}

for these:

if ( size <= this.cattr.getMaxObjects() )
{
     return;
}

should make the trick.