precondition:
caffeine cache only set expire after write 10m.
appearance:
Many of expired cache store in Old-Generation.
case1. The cache survive from 15 ygc, Upgrade into Old-Generation.
case2. Young-Generation don't have enough space to shore this.
Analysis:
The average of YGC, interval is 12m. ps:
1. jstat -gcutil <pid> (gather the num of ygc)
2. top (gather the old of process)
But it may exists that 16 times Ygc in 10minutes. it exists big calculation in special time.
For case1.
We need make the cache can be release before ygc.
add spec param weakValues . it's work!!!. if use the parm <softValues>. the space will be release after FullGC.
to be continue.
