RowCache misses Updates
-----------------------
Key: CASSANDRA-3862
URL: https://issues.apache.org/jira/browse/CASSANDRA-3862
Project: Cassandra
Issue Type: Bug
Components: Core
Affects Versions: 1.0.7
Reporter: Daniel Doubleday
While performing stress tests to find any race problems for CASSANDRA-2864 I
guess I (re-)found one for the standard on-heap row cache.
During my stress test I hava lots of threads running with some of them only
reading other writing and re-reading the value.
This seems to happen:
- Reader tries to read row A for the first time doing a getTopLevelColumns
- Row A which is not in the cache yet is updated by Writer. The row is not
eagerly read during write (because we want fast writes) so the writer cannot
perform a cache update
- Reader puts the row in the cache which is now missing the update
I already asked this some time ago on the mailing list but unfortunately didn't
dig after I got no answer since I assumed that I just missed something. In a
way I still do but haven't found any locking mechanism that makes sure that
this should not happen.
The problem can be reproduced with every run of my stress test. When I restart
the server the expected column is there. It's just missing from the cache.
To test I have created a patch that merges memtables with the row cache. With
the patch the problem is gone.
I can also reproduce in 0.8. Haven't checked 1.1 but I haven't found any
relevant change their either so I assume the same aplies there.
--
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
