JFinal中使用Ehcache缓存是报错?报错

@JFinal 请教个关于Ehcache的问题： 

我用Ehcache缓存一个map，这个map数据量较大，有几千个key，发现Ehcache报一下的错误：

请教一下是什么原因，我已经把配置文件中缓存的对象配置的很大了，diskPersistent也设置为True了。

[2015-06-19 12:30:48,144]-[ERROR]-[system.data]-[net.sf.ehcache.store.disk.DiskStorageFactory$DiskWriteTask#call.488]: Disk Write of sensitive_word failed: 

java.lang.StackOverflowError: null

at java.io.ObjectOutputStream$BlockDataOutputStream.writeBlockHeader(ObjectOutputStream.java:1890) ~[na:1.8.0_25]

at java.io.ObjectOutputStream$BlockDataOutputStream.drain(ObjectOutputStream.java:1875) ~[na:1.8.0_25]

at java.io.ObjectOutputStream$BlockDataOutputStream.setBlockDataMode(ObjectOutputStream.java:1786) ~[na:1.8.0_25]

at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1108) ~[na:1.8.0_25]

at java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:348) ~[na:1.8.0_25]

at java.util.HashMap.internalWriteEntries(HashMap.java:1776) ~[na:1.8.0_25]

at java.util.HashMap.writeObject(HashMap.java:1354) ~[na:1.8.0_25]

at sun.reflect.GeneratedMethodAccessor18.invoke(Unknown Source) ~[na:na]

at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_25]

at java.lang.reflect.Method.invoke(Method.java:483) ~[na:1.8.0_25]

at java.io.ObjectStreamClass.invokeWriteObject(ObjectStreamClass.java:988) ~[na:1.8.0_25]

at java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1496) ~[na:1.8.0_25]

at java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1432) ~[na:1.8.0_25]

at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1178) ~[na:1.8.0_25]

at java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:348) ~[na:1.8.0_25]

at java.util.HashMap.internalWriteEntries(HashMap.java:1777) ~[na:1.8.0_25]

at java.util.HashMap.writeObject(HashMap.java:1354) ~[na:1.8.0_25]

at sun.reflect.GeneratedMethodAccessor18.invoke(Unknown Source) ~[na:na]

at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_25]

at java.lang.reflect.Method.invoke(Method.java:483) ~[na:1.8.0_25]

at java.io.ObjectStreamClass.invokeWriteObject(ObjectStreamClass.java:988) ~[na:1.8.0_25]

at java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1496) ~[na:1.8.0_25]

at java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1432) ~[na:1.8.0_25]

at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1178) ~[na:1.8.0_25]

at java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:348) ~[na:1.8.0_25]