On Mon, Jan 7, 2019 at 7:56 PM Raffaele Gambelli <r.gambe...@westpole.it> wrote:
>
> Hi all,
>
> we are doing many stress tests over our web application above jackrabbit
> 2.14.0.
>
> Starting from a given load, we are experiencing big differences between 4
> nodes versus 2 nodes, I mean that 2 nodes result much more performant than 4
> ones.
>
> We use Oracle 12, only one db node, our PersistenceManager is configured in
> this way:
>
> <PersistenceManager
> class="org.apache.jackrabbit.core.persistence.pool.OraclePersistenceManager">
> <param name="dataSourceName" value="ds1"/>
> <!-- The size of the bundle cache in megabytes, the default is 8 -->
> <param name="bundleCacheSize" value="512"/>
> <param name="consistencyCheck" value="false"/>
> <!-- This size defines the threshold of which size a property is included
> in the bundle or is stored in the blob store, it is in bytes -->
> <param name="minBlobSize" value="16384"/>
> <param name="schemaObjectPrefix" value="${wsp.name}_"/>
> </PersistenceManager>
>
> Have you some hints or best practices to suggest when configure a Jackrabbit
> cluster?
>
> We have noticed that the most active statement is this:
> update JOURNAL_GLOBAL_REVISION set REVISION_ID = REVISION_ID + 1
>
> For which reason it was choosen to have a simple NUMBER column to manage such
> an important information? It is really massively accessed and it may generate
> a big bottle-neck in high concurrency, am I wrong?
That's used by the Cluster journal component. "Every change made by
one cluster node is reported in a journal, ..." [1] Each cluster node
needs to synchronize the changes by reading the journal periodically,
and for that reason, it needs to increment the global revision number
on journal addition, and compare with its own local revision number on
the other cluster nodes. If you've observed that global revision
number update statement, then I think it means your application makes
changes (CUD) very often. If each of your cluster nodes makes the same
amount of changes and so the total changes are increasing in your
stress testing, I guess it should increase the overhead
proportionally.
Regards,
Woonsan
[1] https://wiki.apache.org/jackrabbit/Clustering
>
>
> Thanks in advance, best regards
>
>
>
>
>
>
>
> [westpole]
>
> Raffaele Gambelli
>
> WebRainbow(r) Software Developer
>
>
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