[
https://issues.apache.org/jira/browse/JENA-801?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14206439#comment-14206439
]
Bala Kolla commented on JENA-801:
---------------------------------
I am using the IBM JRE (1.6.x) and WAS 8.1 on Linux 64-bit. System has 64GB of
RAM of which 24GB is set for the heap size.
I have tried setting TransactionManager.QueueBatchSize to 5 (instead of the
default 10) and didn't really see much improvement. Should I try with even
lower number?
If I understood this correctly, we are basically flooding the system with many
queries and at the same doing many updates to TDB and leading to this overhead
on CPU. In this case we will have to take a look at our work load and see if we
can reduce either the query load or the updates to TDB or both.
> When the server is under load, many queries are piling up and seems to be in
> some kind of dead lock.
> ----------------------------------------------------------------------------------------------------
>
> Key: JENA-801
> URL: https://issues.apache.org/jira/browse/JENA-801
> Project: Apache Jena
> Issue Type: Bug
> Components: TDB
> Affects Versions: TDB 0.9.4, Jena 2.11.2
> Reporter: Bala Kolla
> Attachments:
> ThreadLocksInBlockMgrJournalAfterGuavaCacheInNodeTable.htm,
> TracesWithManyItersOfBlockMgrJournal_Valid_Method.txt,
> TracesWithManyItersOfBlockMgrJournal_getRead_Method.txt,
> WAITDataReportShowingTheLockContention.zip,
> WAITDataReportShowingTheLockContentionWithoutQueryFilter.zip
>
>
> We were testing our server with repositories of varied sizes and in almost
> all the cases when the server peaks its capacity (of maximum number of users
> it can support), It seems like the queries are piling up because of the lock
> contention in NodeTableCache.
> Here are some details about the repository..
> size of indices on disk - 150GB
> type of hard disk used - SSD and HDD with high RAM (seeing the same result in
> both the cases)
> OS - Linux
> Details on the user load;
> We are trying to simulate a very active user load where all the users are
> executing many usecases that would result in many queries and updates on TDB.
> I would like to know what are the possible solutions to work around and avoid
> this situation. I am thinking of the following, please let me know if there
> is any other way to work around this bottleneck.
> Control the updates to the triple store so that we only do it when there are
> not many queries pending. We would have to experiment how this impact the
> usecases..
> Is there any other way to make this lock contention go away? Can we have
> multiple instances of this cache? For example many (90%) of our queries are
> executed with a query scope (per project). So, can we have a separate
> NodeTable cache for each query scope (project in our case) and one for
> global?
--
This message was sent by Atlassian JIRA
(v6.3.4#6332)
