Bernhard Stiftner created JENA-1868:
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Summary: 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
Attachments: TDB2StressTest.java
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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