JVM memory full - T4Prepared statement memory and memory dump issues

Often I experience platform crash when JVM free memory becomes very low and full GC does not release any memory.

How to troubleshoot:

• Take memory dump ( in bash jmap -dump:file=/tmp/mon/dump.hprof)
• Open with Eclipse MAT
• Select Dominator tree
• Select Group by class
• Now expand a little bit and let's see what we've got:

37% memory is taken by T4CPrepared statement.

It's parameter in Weblogic - for each thread we can cache 50 queries.

So 197 connections * 50 caches = 9850.

So solution here is to decrease number of caches .