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From "Jason Dillon (JIRA)" <>
Subject [jira] [Commented] (SHIRO-452) SimpleSession serialization failing
Date Wed, 22 Apr 2015 23:52:38 GMT


Jason Dillon commented on SHIRO-452:

Does wrapping this:

with Collections.synchronizedMap() solve this problem?

Also anyone have any idea how to easily reproduce this.  We are seeing this, but I can't figure
out (yet) how to reproduce it easily, its more or less random at this point that I see flurries
of OptionalDataException.

> SimpleSession serialization failing
> -----------------------------------
>                 Key: SHIRO-452
>                 URL:
>             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 ``.
> 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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