[xwiki-devs] monitoring the cache: how to get the eviction rate?

Hello developers, I have been doing a nifty little cache monitor on www.curriki.org which is still running xwiki 1.5.4. It can show the entries and capacity of the two xwiki caches, pageExistCache and the document cache which sound pretty central. Not surprisingly, they're both full on our production server. name entries capacity pageExistCache 10000 10000 cache 3000 3000 The caches are using OSCache (through "OSCacheCache"). I've been trying to get a real statistical count but there I kind of failed thus far. I can use the StatisticListenerImpl which gives fairly high numbers: these numbers are integers, and might actually be too small for the 2billions limit of an int, they are static (so count "all the OSCache instances"). What I would like to get is the "eviction rate" but I do not know how to compute it. That is, I wish to read the number of cache-entries which are thrown away because the cache is full and others come in. Once I can have it, I can start tuning (cache size, less greedy algorithms, ...) and measure the effect of such tuning. We have plenty of RAM space to accommodate the cache but we should use this well. The big annoyance with this process is that it can only run on our production server. So thus far I did not dare register a CacheListener in groovy fearing it would suddenly be slow. Has anyone used a different strategy or tool? I'm happy to post my little monitor script. thanks in advance. paul