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From Sylvain Lebresne <sylv...@datastax.com>
Subject Re: Cassandra 2.0 - AssertionError in ArrayBackedSortedColumns
Date Mon, 22 Jul 2013 07:37:41 GMT
>  unless data was stored in incorrect order and I don't know if that is
> possible through the API..
>

That's exactly what happens and that's why I say it's a bug.


>
> ii. I am also seeing some sporadic cases where a single column cas()
> update is hitting this same issue (the bug you mentioned) as multiple
> columns, do you see any reason for that happening?
>

That would be slightly weirder, but frankly that's almost surely due to
https://issues.apache.org/jira/browse/CASSANDRA-5786 too.

--
Sylvain


> Thank you,
> Soumava
>
>
> On Mon, Jul 22, 2013 at 12:11 AM, Sylvain Lebresne <sylvain@datastax.com>wrote:
>
>> 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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