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https://issues.apache.org/jira/browse/TINKERPOP-3142?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Cole Greer closed TINKERPOP-3142.
---------------------------------
Fix Version/s: 3.7.4
Assignee: Cole Greer
Resolution: Fixed
> TinkerTransactionGraph doesn't remove deleted elements in threaded scenario
> ---------------------------------------------------------------------------
>
> Key: TINKERPOP-3142
> URL: https://issues.apache.org/jira/browse/TINKERPOP-3142
> Project: TinkerPop
> Issue Type: Bug
> Components: tinkergraph
> Affects Versions: 3.7.3
> Reporter: Ken Hu
> Assignee: Cole Greer
> Priority: Critical
> Fix For: 3.7.4
>
>
> Originally discovered from:
> https://stackoverflow.com/questions/79467860/issue-with-transactions-in-local-tinkerpop-gremlin-setup
> [https://groups.google.com/g/gremlin-users/c/NRwb4xy2eXs]
>
> TinkerTransactionGraph might leave a "isDeleted" TinkerElementContainer
> hanging around if a read occurs during the commit of a drop(). This leads to
> later errors when trying to add that element back as it "isDeleted" leading
> to an exception.
> The following test can sometimes reproduce the error (it's a multithreading
> issue so it doesn't always reproduce).
>
> {code:java}
> @Test
> public void shouldAddThenDeleteThenAddBackInSeparateTransactions() throws
> InterruptedException {
> final TinkerTransactionGraph graph = TinkerTransactionGraph.open();
> final GraphTraversalSource g = graph.traversal();
> final GraphTraversalSource gtx = g.tx().begin();
> CountDownLatch signal = new CountDownLatch(1);
> gtx.addV().property(T.id, 1).next();
> gtx.tx().commit();
> Thread reader = new Thread(() -> {
> while (signal.getCount() > 0) {
> g.V().id().toList();
> g.tx().commit();
> }
> });
> reader.start();
> Thread.sleep(50);
> g.V(1).drop().iterate();
> g.tx().commit();
> Thread.sleep(50);
> g.addV().property(T.id, 1).next();
> g.tx().commit();
> signal.countDown();
> reader.join();
> assertEquals(1, graph.getVertices().size());
> } {code}
> Should a read occur when trying to delete the vertex, the usesInTransactions
> is incremented
> ([https://github.com/apache/tinkerpop/blob/3.7.3/tinkergraph-gremlin/src/main/java/org/apache/tinkerpop/gremlin/tinkergraph/structure/TinkerElementContainer.java#L100])
> so that it won't be deleted during the commit as its uses isn't 0
> ([https://github.com/apache/tinkerpop/blob/3.7.3/tinkergraph-gremlin/src/main/java/org/apache/tinkerpop/gremlin/tinkergraph/structure/TinkerElementContainer.java#L232).]
>
> This behavior of incrementing the use count with reads gives more consistent
> reads, however, the tradeoff is that it can cause TransactionExceptions to
> occur. So, it would be best if this could be resolved while keeping the read
> behavior consistent.
>
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