[
https://issues.apache.org/jira/browse/CASSANDRA-12796?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15705225#comment-15705225
]
Sam Tunnicliffe commented on CASSANDRA-12796:
---------------------------------------------
The CI looks reasonable: 3 dtest failures on the 3.0 branch, which all have
corresponding failures upstream, plus a couple of failures on the original 2.2
branch which have since been addressed by other tickets.
The internal paging will aim to read rows in chunks of ~4mb and I've used the
default CQL page size of 10k rows for a floor as it seems like as good a place
to start as any.
[~mmajercik], [~anmols] how does this latest 3.0 version look with your
testing?
> Heap exhaustion when rebuilding secondary index over a table with wide
> partitions
> ---------------------------------------------------------------------------------
>
> Key: CASSANDRA-12796
> URL: https://issues.apache.org/jira/browse/CASSANDRA-12796
> Project: Cassandra
> Issue Type: Bug
> Components: Core
> Reporter: Milan Majercik
> Priority: Critical
>
> We have a table with rather wide partition and a secondary index defined over
> it. As soon as we try to rebuild the index we observed exhaustion of Java
> heap and eventual OOM error. After a lengthy investigation we have managed to
> find a culprit which appears to be a wrong granule of barrier issuances in
> method {{org.apache.cassandra.db.Keyspace.indexRow}}:
> {code}
> try (OpOrder.Group opGroup = cfs.keyspace.writeOrder.start()){html}
> {
> Set<SecondaryIndex> indexes =
> cfs.indexManager.getIndexesByNames(idxNames);
> Iterator<ColumnFamily> pager = QueryPagers.pageRowLocally(cfs,
> key.getKey(), DEFAULT_PAGE_SIZE);
> while (pager.hasNext())
> {
> ColumnFamily cf = pager.next();
> ColumnFamily cf2 = cf.cloneMeShallow();
> for (Cell cell : cf)
> {
> if (cfs.indexManager.indexes(cell.name(), indexes))
> cf2.addColumn(cell);
> }
> cfs.indexManager.indexRow(key.getKey(), cf2, opGroup);
> }
> }
> {code}
> Please note the operation group granule is a partition of the source table
> which poses a problem for wide partition tables as flush runnable
> ({{org.apache.cassandra.db.ColumnFamilyStore.Flush.run()}}) won't proceed
> with flushing secondary index memtable before completing operations prior
> recent issue of the barrier. In our situation the flush runnable waits until
> whole wide partition gets indexed into the secondary index memtable before
> flushing it. This causes an exhaustion of the heap and eventual OOM error.
> After we changed granule of barrier issue in method
> {{org.apache.cassandra.db.Keyspace.indexRow}} to query page as opposed to
> table partition secondary index (see
> [https://github.com/mmajercik/cassandra/commit/7e10e5aa97f1de483c2a5faf867315ecbf65f3d6?diff=unified]),
> rebuild started to work without heap exhaustion.
--
This message was sent by Atlassian JIRA
(v6.3.4#6332)
