[jboss-dev-forums] [Design of Messaging on JBoss (Messaging/JBoss)] - LinkedList Factor on the Journal...

[clebert.suconic@jboss.com]

On the journal, all the messages from all the destinations are stored on a single journal. 

Suppose this scenario where a customer is using two destinations:

- FastDestination
 On this destination, a consumer will be aways there to listen to messages

- LazyDestination
On this destination, a consumer needs to take the action to connect itself (think about e-mails). So he will take days to connect itself again.

Adds and deletes are coming for FastDestination but not for LazyDestination.

For example, you could have something like that on the journal

File1
10 Add Records for Lazy
8000 Add Records for Fast

File2
8000 Delete Records for Fast
100 Add Records for Fast

File3
100 Delete Records for Fast
300 Add Records for Fast

File4
599 Add Records for fast
...

On this simple Example... even though all FastRecords from File1, 2 and 3 are gone, the Journal won't be able to reclaim any files until these 10 Lazy records are gone.

If Lazy takes for instance 3 days to read its destinations, we will need probably 1 thousand journal files on the journal (or even more).

It will be fairly difficult to eventually reload the journal (It would require a lot of memory).


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