incubator-cassandra-user mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From sulong <sulong1...@gmail.com>
Subject Re: Why does cassandra PoolingSegmentedFile recycle the RandomAccessReader?
Date Tue, 16 Jul 2013 02:32:46 GMT
Yes, that's what I am looking for. Thanks.


On Mon, Jul 15, 2013 at 10:08 PM, Jake Luciani <jakers@gmail.com> wrote:

> Take a look at https://issues.apache.org/jira/browse/CASSANDRA-5661
>
>
> On Mon, Jul 15, 2013 at 4:18 AM, sulong <sulong1984@gmail.com> wrote:
>
>> Thanks for your help. Yes, I will try to increase the sstable size. I
>> hope it can save me.
>>
>> 9000 SSTableReader x 10 RandomAccessReader x 64Kb = 5.6G memory. If there
>> is only one RandomAccessReader, the memory will be 9000 * 1 * 64Kb = 0.56G
>> . Looks great. But I think it must be reasonable to recycle the
>> RandomAccessReader.
>>
>>
>> On Mon, Jul 15, 2013 at 4:02 PM, Janne Jalkanen <janne.jalkanen@ecyrd.com
>> > wrote:
>>
>>>
>>> I had exactly the same problem, so I increased the sstable size (from 5
>>> to 50 MB - the default 5MB is most certainly too low for serious usecases).
>>>  Now the number of SSTableReader objects is manageable, and my heap is
>>> happier.
>>>
>>> Note that for immediate effect I stopped the node, removed the *.json
>>> files and restarted - which put all SSTables to L0, which meant a weekend
>>> full of compactions… Would be really cool if there was a way to
>>> automatically drop all LCS SSTables one level down to make them compact
>>> earlier without avoiding the
>>> "OMG-must-compact-everything-aargh-my-L0-is-full" -effect of removing the
>>> JSON file.
>>>
>>> /Janne
>>>
>>> On 15 Jul 2013, at 10:48, sulong <sulong1984@gmail.com> wrote:
>>>
>>> > Why does cassandra PoolingSegmentedFile recycle the
>>> RandomAccessReader? The RandomAccessReader objects consums too much memory.
>>> >
>>> > I have a cluster of 4 nodes. Every node's cassandra jvm has 8G heap.
>>> The cassandra's memory is full after about one month, so I have to restart
>>> the 4 nodes every month.
>>> >
>>> > I have 100G data on every node, with LevedCompactionStrategy and 10M
>>> sstable size, so there are more than 10000 sstable files. By looking
>>> through the heap dump file, I see there are more than 9000 SSTableReader
>>> objects in memory, which references lots of  RandomAccessReader objects.
>>> The memory is consumed by these RandomAccessReader objects.
>>> >
>>> > I see the PoolingSegementedFile has a recycle method, which puts the
>>> RandomAccessReader to a queue. Looks like the Queue always grow until the
>>> sstable is compacted.  Is there any way to stop the RandomAccessReader
>>> recycling? Or, set a limit to the recycled RandomAccessReader's number?
>>> >
>>> >
>>>
>>>
>>
>
>
> --
> http://twitter.com/tjake
>

Mime
View raw message