[
https://issues.apache.org/jira/browse/CASSANDRA-3821?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13201768#comment-13201768
]
Yuki Morishita commented on CASSANDRA-3821:
-------------------------------------------
Here is my initial look at the issue (might be wrong):
Concurrent counter mutation replay from commitlog and AtomicSortedColumns
inside Memtable seem to be the cause of over count.
There is a race condition when adding column to memtable, and when it happens
AtomicSortedColumns calls {{{IColumn#reconcile}}} multiple times until column
is stored. It causes over count since counter column's {{reconcile}} is not
idempotent operation.
> Counters in super columns don't preserve correct values after cluster restart
> -----------------------------------------------------------------------------
>
> Key: CASSANDRA-3821
> URL: https://issues.apache.org/jira/browse/CASSANDRA-3821
> Project: Cassandra
> Issue Type: Bug
> Components: Core
> Affects Versions: 1.1
> Environment: ubuntu, 'trunk' branch, used ccm to create a 3 node
> cluster with rf=3. A dtest was created to demonstrate.
> Reporter: Tyler Patterson
>
> Set up a 3-node cluster with rf=3. Create a counter super column family and
> increment a bunch of subcolumns 100 times each, with cf=QUORUM. Then wait a
> few second, restart the cluster, and read the values back. They almost all
> come back different (and higher) then they are supposed to be.
> Here are some extra things I've noticed:
> - Reading back the values before the restart always produces correct results.
> - Doing a nodetool flush before killing the cluster greatly improves the
> results, though sometimes a value will still be incorrect. You might have to
> run the test several times to see an incorrect value after a flush.
> - This problem doesn't happen on C* 1.0.7, unless you don't sleep between
> doing the increments and killing the cluster. Then it sometimes happens to a
> lesser degree.
> The dtest that demonstrates this issue is called "super_counter_test.py". Run
> it like this: nosetests --nocapture super_counter_test.py You'll need ccm
> from [email protected]:tpatterson/ccm.git.
--
This message is automatically generated by JIRA.
If you think it was sent incorrectly, please contact your JIRA administrators:
https://issues.apache.org/jira/secure/ContactAdministrators!default.jspa
For more information on JIRA, see: http://www.atlassian.com/software/jira
