[jira] [Created] (CASSANDRA-9568) commit_sync: batch either doesn't work or has confusing documentation

["Jim Witschey (JIRA)" <ji...@apache.org>]

Jim Witschey created CASSANDRA-9568:
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             Summary: commit_sync: batch either doesn't work or has confusing documentation
                 Key: CASSANDRA-9568
                 URL: https://issues.apache.org/jira/browse/CASSANDRA-9568
             Project: Cassandra
          Issue Type: Bug
            Reporter: Jim Witschey


Based on the language [here|http://docs.datastax.com/en/cassandra/2.1/cassandra/configuration/configCassandra_yaml_r.html?scroll=reference_ds_qfg_n1r_1k__commitlog_sync], I thought that when {{commitlog_sync}} was set to {{batch}}, inserts would block until the commitlog was written to and fsynced. As the docs say,

{quote}
When using this method, writes are not acknowledged until fsynced to disk.
{quote}

This doesn't seem to be the case. I've pushed a failing dtest [here|https://github.com/riptano/cassandra-dtest/compare/master...mambocab:commitlog_sync-batch-bug] demonstrating the behavior; even after writing thousands of rows, the size of the commitlog doesn't change. I see similar values when measuring the commitlog size via JMX, so I don't believe it's a measurement error on my part. I see this behavior on trunk and on HEAD for 2.2, 2.1, and 2.0.

This should either be fixed, or the behavior should be more clearly documented. I asked about the intended behavior in #cassandra and didn't get an answer.



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