[jira] [Commented] (SHIRO-452) SimpleSession serialization failing

["Andreas Kohn (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/SHIRO-452?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14615311#comment-14615311 ] 

Andreas Kohn commented on SHIRO-452:
------------------------------------

FWIW: We fixed our OptionalDataExceptions by configuring ehcache to use {{copyonwrite}} for the shiro-activeSessionCache. In our case the issue seems to have to been caused by shiro's logic to update the session last access time. Unfortunately I do not have the original exception anymore, only the commit message for the change of the configuration :/

> SimpleSession serialization failing
> -----------------------------------
>
>                 Key: SHIRO-452
>                 URL: https://issues.apache.org/jira/browse/SHIRO-452
>             Project: Shiro
>          Issue Type: Bug
>          Components: Caching , Session Management
>    Affects Versions: 1.2.1
>         Environment: Java 6 - EhCache 2.6.2
>            Reporter: Bruno GRIEDER
>
> We cache SimpleSession in EhCache which is configured with Overflow to Disk and an LRU eviction policy.
> When the cache is full, EhCache will attempt to evict a session from the Disk Storage to reclaim space.
> To evict the `SimpleSession`, EhCache will attempt to deserialize the eveicted session first. From time to time, the deserialization of the `SimpleSession` fails. When that happens the system is locked, since no additional session can be created.
> `SimpleSession` has a custom serialization mechanism that calculates a bit mask which indicates which fields of the `SimpleSession` contain values. This bitMask is serialized first (as a Short) then the fields containing values.
> When deserialization is failing, the bitMask indicates that the `attributes` Map contains data, however no `attributes` have actually been serialized and the deserialization fails with a `java.io.OptionalDataException`.
> The discrepancy is very likely due to `attributes` being a non synchronized Map: the SimpleSession is created on a Servlet thread, however the serialization to Disk is performed by EhCache on one of its cache management threads.
> SimpleSession fields should likely be marked as volatile and the Map should be a Synchronized Map or SimpleSession should be made immutable.



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