[jboss-jira] [JBoss JIRA] Commented: (JBMESSAGING-1162) JBM takes eons to startup with topic persisted messages within db

[Gabriele Garuglieri (JIRA)]

    [ http://jira.jboss.com/jira/browse/JBMESSAGING-1162?page=comments#action_12390667 ] 
            
Gabriele Garuglieri commented on JBMESSAGING-1162:
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Hi Tim,
perhaps i didn't explain myself well.

Depending on the number of messages persisted in db there's a minimum value for FullSize under which JBM will refuse to start.
For instance from several runs we got the following results:
Messages    min FullSize
180000         8000
300000         8188
600000         8880
900000         9500
1428188      26188

More or less linear until 900000 messages but then the line heads up. Even worst it doesn't even have constant slope, with 1428188 msgs after a first good start with 26188 on the second run JBM refused to start unless FullSize was larger than 36000. (i lost the log of that run and don't remember exact value, but it was slightly more than 36000).

Definitely there is a relation between minimum FullSize value and number of persisted messages, but once the relation changed from linear to something else and i started getting changing values for the same amount of messages it was impossible to determine it.
Hence my request to document it.

And again max value for PageSize and DownCacheSize looks to have a relation with FullSize. And IMO also this should be documented.

When you have to deal with very large number of messages these values are crucial for optimal performances and deserves a better documentation.


My second point was that doesn't matter how well i tune Oracle, if i'm forced to serially load in memory FullSize amount of messages for each queue/topic from a db that contains tenth of millions of messages i'll always count startup times in tenth of minutes.

Hence my second question, why JBM needs to serially load messages for each queue/topic before startup instead of being able to parallel load messages at first queue/topic access?

Thank you,  Gabriele

> JBM takes eons to startup with topic persisted messages within db
> -----------------------------------------------------------------
>
>                 Key: JBMESSAGING-1162
>                 URL: http://jira.jboss.com/jira/browse/JBMESSAGING-1162
>             Project: JBoss Messaging
>          Issue Type: Bug
>          Components: Messaging Core Persistence
>    Affects Versions: 1.4.0.SP1
>         Environment: Java 1.5.0_14
> JBoss 4.2.2
> Solaris 10, AMD Opteron biprocessor machine
>            Reporter: Gabriele Garuglieri
>         Assigned To: Tim Fox
>            Priority: Critical
>
> The problem is reproduced as follows:
> 1-Start server
> 2-start a producer that inserts persisted messages (we tried 90.000 messages) in TestTopic topic with default configuration where there are some consumers subscribed but not active
> 3-stop producer and orderly shutdown the server
> 4-start server
> During server startup JBM executes a select to load the persisted messages id's then executes 180 selects loading 500 messages at time.
> With 90.000 messages those 180 selects takes about 10 minutes. The DBMS is Oracle 10g with dedicated instance on a separate machine with no more than 1% cpu load during test and physical db on a very fast NAS.
> While JBM is executing those selects, obviously the server startup hangs until the load is finished.

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