[jira] [Comment Edited] (JENA-2086) TDB2: read transactions sync the journal.

["Andy Seaborne (Jira)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/JENA-2086?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17318926#comment-17318926 ] 

Andy Seaborne edited comment on JENA-2086 at 4/12/21, 8:35 AM:
---------------------------------------------------------------

Hi Marco,

Yes, all routes go via Journal.sync. It is unnecessary for a read transaction and I'll testing a fix that simply skips the journal in a read-cleanup. Being this deep in the transaction system, means being very careful. I haven't found a reason while it used to work better.
----
Update: As far as I can tell  the code here has been the same since TDB2 was introduced into Jena (JENA-1397; Jena 3.5.0). There have been a couple of major changes over the years making it hard to be certain - the code is there, but code call paths may have changed.) TDB1 and TDB2 are completely different in the way they work for transactions.


was (Author: andy.seaborne):
Hi Marco,

Yes, all routes go via Journal.sync. It is unnecessary for a read transaction and I'll testing a fix that simply skips the journal in a read-cleanup. Being this deep in the transaction system, means being very careful. I haven't found a reason while it used to work better.



> TDB2: read transactions sync the journal.
> -----------------------------------------
>
>                 Key: JENA-2086
>                 URL: https://issues.apache.org/jira/browse/JENA-2086
>             Project: Apache Jena
>          Issue Type: Improvement
>          Components: TDB2
>    Affects Versions: Jena 3.17.0, Jena 4.0.0
>            Reporter: Andy Seaborne
>            Assignee: Andy Seaborne
>            Priority: Major
>         Attachments: jena-sync-overhead.png
>
>
> [Report from users@ (2021-04-08)|https://lists.apache.org/thread.html/rbc1ff0ae78359b580786ff76ad006f1edeca4da13b0f946cd4f48a8d%40%3Cusers.jena.apache.org%3E]
> See attached for stacktrace mentioned in the report.
> A simple UC:
> {noformat}
>         DatasetGraph dsg = DatabaseMgr.createDatasetGraph();
>         dsg.executeRead(()->{});
> {noformat}
> and breakpoint on Journal.sync:
> {noformat}
>     Journal.sync() line: 384	
>     Journal.reset() line: 397	
>     TransactionCoordinator.completed(Transaction) line: 708	
>     Transaction.endInternal() line: 218	
>     Transaction.commit() line: 182	
>     TransactionalBase.commitExec() line: 143	
>     TransactionalBase(TransactionalSystem).commit() line: 33	
>     TransactionalBase.commit() line: 131	
>     DatasetGraphTDB(DatasetGraphStorage).commit() line: 69	
>     DatasetGraphSwitchable(DatasetGraphWrapper).commit() line: 276	
>     Txn.exec(T, TxnType, Runnable) line: 85	
>     Txn.executeRead(T, Runnable) line: 115	
>     DatasetGraphSwitchable(Transactional).executeRead(Runnable) line: 249	
>     Report.main(String[]) line: 70
> {noformat}



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