[jira] [Commented] (JENA-1868) TDB2 Concurrency: NPE in TransactionalComponentLifecycle

["Bernhard Stiftner (Jira)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/JENA-1868?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17064781#comment-17064781 ] 

Bernhard Stiftner commented on JENA-1868:
-----------------------------------------

Proposed fix: https://github.com/apache/jena/pull/713

> TDB2 Concurrency: NPE in TransactionalComponentLifecycle
> --------------------------------------------------------
>
>                 Key: JENA-1868
>                 URL: https://issues.apache.org/jira/browse/JENA-1868
>             Project: Apache Jena
>          Issue Type: Bug
>          Components: TDB2
>    Affects Versions: Jena 3.14.0
>            Reporter: Bernhard Stiftner
>            Priority: Major
>         Attachments: TDB2StressTest.java
>
>          Time Spent: 10m
>  Remaining Estimate: 0h
>
> We're evaluating moving from TDB1 to TDB2 and are hitting various concurrency/thread-safety issues that apparently didn't exist with TDB1.
> Our setting is as follows: one JVM, ~20 independent TDB1/TDB2 instances, highly concurrent workload involving every TDB1/TDB2 instance.
> A common issue we're hitting with TDB2 is this NullPointerException in TransactionalComponentLifecycle:
> {noformat}
> java.lang.NullPointerException
>     at org.apache.jena.dboe.transaction.txn.TransactionalComponentLifecycle.getReadWriteMode(TransactionalComponentLifecycle.java:324)
>     at org.apache.jena.dboe.transaction.txn.TransactionalComponentLifecycle.complete(TransactionalComponentLifecycle.java:143)
>     at org.apache.jena.dboe.transaction.txn.SysTrans.complete(SysTrans.java:47)
>     at org.apache.jena.dboe.transaction.txn.Transaction.lambda$endInternal$16(Transaction.java:220)
>     at java.base/java.util.ArrayList.forEach(ArrayList.java:1540)
>     at org.apache.jena.dboe.transaction.txn.Transaction.endInternal(Transaction.java:220)
>     at org.apache.jena.dboe.transaction.txn.Transaction.end(Transaction.java:209)
>     at org.apache.jena.dboe.transaction.txn.TransactionalBase._end(TransactionalBase.java:262)
>     at org.apache.jena.dboe.transaction.txn.TransactionalBase.abort(TransactionalBase.java:159)
>     at org.apache.jena.dboe.storage.system.DatasetGraphStorage.abort(DatasetGraphStorage.java:63)
>     at org.apache.jena.sparql.core.DatasetGraphWrapper.abort(DatasetGraphWrapper.java:253)
>     at org.apache.jena.sparql.core.DatasetImpl.abort(DatasetImpl.java:158)
>     at TDB2StressTest.randomRead(TDB2StressTest.java:87)
>     at TDB2StressTest.runStressTestWorker(TDB2StressTest.java:64)
>     at TDB2StressTest.lambda$runStressTest$0(TDB2StressTest.java:43)
>     at java.base/java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:515)
>     at java.base/java.util.concurrent.FutureTask.run(FutureTask.java:264)
>     at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1128)
>     at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:628)
>     at java.base/java.lang.Thread.run(Thread.java:834)
> {noformat}
> The attached "test case" manages to reproduce this issue most of the time on my machine (YMMV of course, since the test is based on quite some concurrency voodoo).
> The same test is working flawlessly when run against a TDB1 backend.



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