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From crypto five <cryptof...@gmail.com>
Subject Re: Cassandra dying when gets many deletes
Date Wed, 25 Apr 2012 06:08:03 GMT
I agree with your observations.
>From another hand I found that ColumnFamily.size() doesn't calculate object
size correctly. It doesn't count two fields Objects sizes and returns 0 if
there is no object in columns container.
I increased initial size variable value to 24 which is size of two
objects(I didn't now what's correct value), and cassandra started
calculating live ratio correctly, increasing trhouhput value and flushing
memtables.

On Tue, Apr 24, 2012 at 2:00 AM, Vitalii Tymchyshyn <tivv00@gmail.com>wrote:

> **
> Hello.
>
> For me " there are no dirty column families" in your message tells it's
> possibly the same problem.
> The issue is that column families that gets full row deletes only do not
> get ANY SINGLE dirty byte accounted and so can't be picked by flusher. Any
> ratio can't help simply because it is multiplied by 0. Check your cfstats.
>
> 24.04.12 09:54, crypto five написав(ла):
>
> Thank you Vitalii.
>
>  Looking at the Jonathan's answer to your patch I think it's probably not
> my case. I see that LiveRatio is calculated in my case, but calculations
> look strange:
>
>  WARN [MemoryMeter:1] 2012-04-23 23:29:48,430 Memtable.java (line 181)
> setting live ratio to maximum of 64 instead of Infinity
>  INFO [MemoryMeter:1] 2012-04-23 23:29:48,432 Memtable.java (line 186)
> CFS(Keyspace='lexems', ColumnFamily='countersCF') liveRatio is 64.0
> (just-counted was 64.0).  calculation took 63355ms for 0 columns
>
>  Looking at the comments in the code: "If it gets higher than 64
> something is probably broken.", looks like it's probably the problem.
> Not sure how to investigate it.
>
> 2012/4/23 Віталій Тимчишин <tivv00@gmail.com>
>
>> See https://issues.apache.org/jira/browse/CASSANDRA-3741
>> I did post a fix there that helped me.
>>
>>
>> 2012/4/24 crypto five <cryptofive@gmail.com>
>>
>>> Hi,
>>>
>>>  I have 50 millions of rows in column family on 4G RAM box. I
>>> allocatedf 2GB to cassandra.
>>> I have program which is traversing this CF and cleaning some data there,
>>> it generates about 20k delete statements per second.
>>> After about of 3 millions deletions cassandra stops responding to
>>> queries: it doesn't react to CLI, nodetool etc.
>>> I see in the logs that it tries to free some memory but can't even if I
>>> wait whole day.
>>> Also I see following in  the logs:
>>>
>>>  INFO [ScheduledTasks:1] 2012-04-23 18:38:13,333 StorageService.java
>>> (line 2647) Unable to reduce heap usage since there are no dirty column
>>> families
>>>
>>>  When I am looking at memory dump I see that memory goes to
>>> ConcurrentSkipListMap(10%), HeapByteBuffer(13%), DecoratedKey(6%),
>>> int[](6%), BigInteger(8.2%), ConcurrentSkipListMap$HeadIndex(7.2%),
>>> ColumnFamily(6.5%), ThreadSafeSortedColumns(13.7%), long[](5.9%).
>>>
>>>  What can I do to make cassandra stop dying?
>>> Why it can't free the memory?
>>> Any ideas?
>>>
>>>  Thank you.
>>>
>>
>>
>>
>>   --
>> Best regards,
>>  Vitalii Tymchyshyn
>>
>
>
>

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