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Posted to commits@cassandra.apache.org by "Sylvain Lebresne (JIRA)" <ji...@apache.org> on 2013/08/23 09:44:52 UTC
[jira] [Commented] (CASSANDRA-5925) Race condition in update
lightweight transaction
[ https://issues.apache.org/jira/browse/CASSANDRA-5925?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13748373#comment-13748373 ]
Sylvain Lebresne commented on CASSANDRA-5925:
---------------------------------------------
Don't you have more stack trace in the log? To have a NPE in the MutationStage is definitively a bug, but it would be immensely easier to find what's the problem with a stack trace. And there should be a trace.
> Race condition in update lightweight transaction
> ------------------------------------------------
>
> Key: CASSANDRA-5925
> URL: https://issues.apache.org/jira/browse/CASSANDRA-5925
> Project: Cassandra
> Issue Type: Bug
> Environment: 3 node Cassandra 2.0.0-rc2 cluster. Java driver 1.0.2.
> Reporter: Phil Persad
>
> I'm building some tests for a Cassandra PoC. One scenario I need to test is consumption of 1 time tokens. These tokens must be consumed exactly once. The cluster involved is a 3 node cluster. All queries are run with ConsistencyLevel.QUORUM. I'm using the following queries:
> CREATE KEYSPACE IF NOT EXISTS test WITH replication = { 'class' : 'SimpleStrategy', 'replication_factor' : 3 };
> CREATE TABLE IF NOT EXISTS tkns (tkn blob, consumed boolean, PRIMARY KEY (tkn));
> INSERT INTO tkns (tkn, consumed) VALUES (?,FALSE) USING TTL 30;
> UPDATE tkns USING TTL 1 SET consumed = TRUE WHERE tkn = ? IF consumed = FALSE;
> I use the '[applied]' column in the result set of the update statement to determine whether the token has been successfully consumed or if the token is being replayed.
> My test involves concurrently executing many sets of 1 insert and 2 update statements (using Session#execute on BoundStatemnts) then checking to make sure that only one of the updates was applied.
> When I run this test with relatively few iterations (~100) my results are what I expect (exactly 1 update succeeds). At ~1000 iterations, I start seeing both updates reporting success in 1-2% of cases. While my test is running, I see corresponding error entries in the Cassandra log:
> ERROR 15:34:53,583 Exception in thread Thread[MutationStage:522,5,main]
> java.lang.NullPointerException
> ERROR 15:34:53,584 Exception in thread Thread[MutationStage:474,5,main]
> java.lang.NullPointerException
> ERROR 15:34:53,584 Exception in thread Thread[MutationStage:536,5,main]
> java.lang.NullPointerException
> ERROR 15:34:53,729 Exception in thread Thread[MutationStage:480,5,main]
> java.lang.NullPointerException
> ERROR 15:34:53,729 Exception in thread Thread[MutationStage:534,5,main]
> java.lang.NullPointerException
> Thanks.
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