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From Sylvain Lebresne <sylv...@datastax.com>
Subject Re: Cassandra 2.0 - AssertionError in ArrayBackedSortedColumns
Date Mon, 22 Jul 2013 07:11:58 GMT
This is a bug really: https://issues.apache.org/jira/browse/CASSANDRA-5786.

This should get fixed in the next beta of 2.0, but if you really want to
test CAS updates in the meantime, you'll have to provide the columns in
(column family comparator) sorted order to the thrift cas() method.

--
Sylvain


On Sun, Jul 21, 2013 at 1:22 PM, Soumava Ghosh <soumava@cs.utexas.edu>wrote:

> Hi,
>
> I'm taking a look at the Check and Set functionalities provided by the
> cas() API provided by cassandra 2.0 (the code available on git). I'm
> running a few tests on a small sized cluster (replication factor 3,
> consistency level quorum) with a few clients. I've observed a lot of cases
> seem to hit the TimedOutException while paxos is in progress. On inspection
> of the server side logs the following stack was seen:
>
> ERROR [Thread-582] 2013-07-21 01:17:46,169 CassandraDaemon.java (line 196)
> Exception in thread Thread[Thread-582,5,main]
> java.lang.AssertionError: Added column does not sort as the last column
>         at
> org.apache.cassandra.db.ArrayBackedSortedColumns.addColumn(ArrayBackedSortedColumns.java:115)
>         at
> org.apache.cassandra.db.ColumnFamily.addColumn(ColumnFamily.java:117)
>         at
> org.apache.cassandra.db.ColumnFamilySerializer.deserialize(ColumnFamilySerializer.java:119)
>         at
> org.apache.cassandra.db.ColumnFamilySerializer.deserialize(ColumnFamilySerializer.java:96)
>         at
> org.apache.cassandra.db.ColumnFamilySerializer.deserialize(ColumnFamilySerializer.java:91)
>         at
> org.apache.cassandra.service.paxos.Commit$CommitSerializer.deserialize(Commit.java:139)
>         at
> org.apache.cassandra.service.paxos.Commit$CommitSerializer.deserialize(Commit.java:128)
>         at org.apache.cassandra.net.MessageIn.read(MessageIn.java:99)
>         at
> org.apache.cassandra.net.IncomingTcpConnection.receiveMessage(IncomingTcpConnection.java:175)
>         at
> org.apache.cassandra.net.IncomingTcpConnection.handleModernVersion(IncomingTcpConnection.java:135)
>         at
> org.apache.cassandra.net.IncomingTcpConnection.run(IncomingTcpConnection.java:82)
>
> I was updating multiple columns using the same cas() call, and looking at
> the assert (code below) I added code to sort them before sending.
> However, now I'm seeing the same issue *even with single column* cas()
> calls.
>
>         int c = internalComparator().compare(columns.get(getColumnCount()
> - 1).name(), column.name());
>         // note that we want an assertion here (see addColumn javadoc),
> but we also want that if
>         // assertion are disabled, addColumn works correctly with unsorted
> input
>         assert c <= 0 : "Added column does not sort as the " + (reversed ?
> "first" : "last") + " column";
>
> I have also seen this error occur in the getRow() path, as below:
>
> java.lang.AssertionError: Added column does not sort as the last column
>         at
> org.apache.cassandra.db.ArrayBackedSortedColumns.addColumn(ArrayBackedSortedColumns.java:115)
>         at
> org.apache.cassandra.db.ColumnFamily.addColumn(ColumnFamily.java:117)
>         at
> org.apache.cassandra.db.ColumnFamily.addAtom(ColumnFamily.java:151)
>         at
> org.apache.cassandra.db.CollationController.collectTimeOrderedData(CollationController.java:95)
>         at
> org.apache.cassandra.db.CollationController.getTopLevelColumns(CollationController.java:57)
>         at
> org.apache.cassandra.db.ColumnFamilyStore.getTopLevelColumns(ColumnFamilyStore.java:1452)
>         at
> org.apache.cassandra.db.ColumnFamilyStore.getColumnFamily(ColumnFamilyStore.java:1281)
>         at
> org.apache.cassandra.db.ColumnFamilyStore.getColumnFamily(ColumnFamilyStore.java:1195)
>         at org.apache.cassandra.db.Table.getRow(Table.java:331)
>         at
> org.apache.cassandra.db.SliceByNamesReadCommand.getRow(SliceByNamesReadCommand.java:55)
>         at
> org.apache.cassandra.service.StorageProxy$LocalReadRunnable.runMayThrow(StorageProxy.java:1288)
>         at
> org.apache.cassandra.service.StorageProxy$DroppableRunnable.run(StorageProxy.java:1813)
>         at
> java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
>         at
> java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
>         at java.lang.Thread.run(Thread.java:722)
>
> Could someone provide me a little more clarity about what the context of
> the error is and what the client needs to do to fix it? I understand that
> running with assertions disabled would do away with this error, but i'd
> like to know if there is a proper way to fix this. Moreover, what could
> possibly be going wrong in the get path that is hitting this issue?
>
> Some guidance, on the fact that whether it is expected that the client
> sort the columns before calling the API with multiple columns, would be
> really appreciated.
>
> Thanks,
> Soumava
>

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