Robert Wille created CASSANDRA-9194:
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Summary: Delete-only workloads crash Cassandra
Key: CASSANDRA-9194
URL: https://issues.apache.org/jira/browse/CASSANDRA-9194
Project: Cassandra
Issue Type: Bug
Environment: 2.0.14
Reporter: Robert Wille
The size of a tombstone is not properly accounted for in the memtable. A
memtable which has only tombstones will never get flushed. It will grow until
the JVM runs out of memory. The following program easily demonstrates the
problem.
Cluster.Builder builder = Cluster.builder();
Cluster c =
builder.addContactPoints("cas121.devf3.com").build();
Session s = c.connect();
s.execute("CREATE KEYSPACE IF NOT EXISTS test WITH replication
= { 'class' : 'SimpleStrategy', 'replication_factor' : 1 }");
s.execute("CREATE TABLE IF NOT EXISTS test.test(id INT PRIMARY
KEY)");
PreparedStatement stmt = s.prepare("DELETE FROM test.test WHERE
id = :id");
int id = 0;
while (true)
{
s.execute(stmt.bind(id));
id++;
}
This program should run forever, but eventually Cassandra runs out of heap and
craps out. You needn't wait for Cassandra to crash. If you run "nodetool
cfstats test.test" while it is running, you'll see Memtable cell count grow,
but Memtable data size will remain 0.
This issue was fixed once before. I received a patch for version 2.0.5 (I
believe), which contained the fix, but the fix has apparently been lost,
because it is clearly broken, and I don't see the fix in the change logs.
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