Phil Persad created CASSANDRA-5925:
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Summary: 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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