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https://issues.apache.org/jira/browse/JCR-1253?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#action_12551458
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Thomas Mueller commented on JCR-1253:
-------------------------------------
Hi,
I think performance is important, but I am not sure if keeping autocommit off
will help. I have tested it using
org.apache.jackrabbit.core.persistence.bundle.DerbyPersistenceManager and the
trunk. Removing setAutoCommit didn't have an effect on performance on my
machine. Sometimes it is slower, sometimes faster. My results are:
with setAutoCommit(true):
3640
4688
4250
3672
3672
total: 19922
without:
3813
4687
4766
4281
3906
total: 21453
(So in this case, it was actually slower with the change)
Test case:
public class TestStore {
public static void main(String[] args) throws Exception {
Repository repository = (Repository) new TransientRepository();
Credentials credentials = new SimpleCredentials("admin", "admin"
.toCharArray());
Session session = repository.login(credentials);
Node testNode = session.getRootNode().addNode("testNode");
session.save();
long start = System.currentTimeMillis();
for(int j = 0; j < 5; j++) {
long time = System.currentTimeMillis();
for (int i = 0; i < 100; i++) {
testNode.setProperty("int", i);
testNode.save();
}
System.out.println(System.currentTimeMillis() - time);
}
System.out.println("total: " + (System.currentTimeMillis() - start));
testNode.remove();
session.save();
session.logout();
}
}
> Allow to configure autoCommit mode for BundleDB PM to avoid extra overhead
> when working in non clustered environment
> --------------------------------------------------------------------------------------------------------------------
>
> Key: JCR-1253
> URL: https://issues.apache.org/jira/browse/JCR-1253
> Project: Jackrabbit
> Issue Type: Improvement
> Components: jackrabbit-core
> Affects Versions: 1.3.3, 1.4
> Reporter: Przemo Pakulski
> Priority: Minor
> Fix For: 1.4
>
> Attachments: single_checkin.JPG, small_change_log.JPG
>
>
> BundleDB PMs keeps connection open in autoCommit mode and during every store
> operation turn off/on this flag introducing some overhead.
> '... the reason is that in a clustered environment, the 'select' statements
> must be committed as well, otherwise the tables remain locked. and
> instead of explicitly commit each time after a read, we used the
> autocommit as default and switch it off during store ...'
> We could add additional parameter which allows to configure autoCommit mode,
> by default it could work as before, but specifing additional parameter will
> change the behaviour.
> It's hard to say about exact numbers how much overhead it is, there are to
> many variables (network speed/latency, db server type, jdbc driver, change
> log size). For sure it means 2 extra network calls, which could be easily
> avoided.
> See attached example screen from JProfiler using MSSQL server, and small
> change logs; overhead is about 20%. Doing simple checkin on versionable node
> it could be even 40%.
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