[jboss-user] [JBossCache] - Re: Apparently losing data

[uuderzo]

anonymous wrote : So, you mean that calls to TreeCache.put(x,y); stop working? How do you know this? 

I don't mean that those calls stop working, but something starts going wrong. 

I try to explain better the flow of data in tree cache:

1. User logon => TreeCache.put( x, y ), where x is the user session "ticket" and y is the user session data.

2. Business logic needs user session data => TreeCache.get( x, y ), y is updated with last call time information. After that => TreeCache.put( x, y ). y is returned

3. Iterate step 2 for the entire life of a user session

4. When user logs off => TreeCache.remove( x )

This is a simplified flow but this is the way our system works. And it works well until something breaks and the step 2 starts returning NULL instead of user session data. I don't understand if the data is corrupted when putting into cache in step 1, or when re-putting in step 2 or because tree cache "forgets" the node and starts returning NULL.

The problem does not happen frequently (about once a month) so it's difficult for me to track the data path and understand what's happening.

What I know is that in 99,9% cases it works great and that if I can get an object from the cache and set a field of this object, it must be not null. After updating the field I re-put into the cache and cycle this.

Another thing that I know is that the system can work well for weeks but once the malfunction appears it's no more possible to use it. I mean that after the first malfunctioning session, forther new sessions get the same malfunction. Restarting the application server solves the problem, until it reappears in near future. So it lets me think about something going wrong into the cahe.

I just wish to know if my approach has something "buggy" or if there is a real possibility that the cache starts forgetting after "something" happened,  even without eviction policies installed.

Thanks again.

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