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From Bryan Talbot <btal...@aeriagames.com>
Subject Re: Heap is not released and streaming hangs at 0%
Date Fri, 21 Jun 2013 23:12:17 GMT
bloom_filter_fp_chance = 0.7 is probably way too large to be effective and
you'll probably have issues compacting deleted rows and get poor read
performance with a value that high.  I'd guess that anything larger than
0.1 might as well be 1.0.

-Bryan



On Fri, Jun 21, 2013 at 5:58 AM, srmore <comomore@gmail.com> wrote:

>
> On Fri, Jun 21, 2013 at 2:53 AM, aaron morton <aaron@thelastpickle.com>wrote:
>
>> > nodetool -h localhost flush didn't do much good.
>>
>> Do you have 100's of millions of rows ?
>> If so see recent discussions about reducing the bloom_filter_fp_chance
>> and index_sampling.
>>
> Yes, I have 100's of millions of rows.
>
>
>>
>> If this is an old schema you may be using the very old setting of
>> 0.000744 which creates a lot of bloom filters.
>>
>> bloom_filter_fp_chance value that was changed from default to 0.1, looked
> at the filters and they are about 2.5G on disk and I have around 8G of heap.
> I will try increasing the value to 0.7 and report my results.
>
> It also appears to be a case of hard GC failure (as Rob mentioned) as the
> heap is never released, even after 24+ hours of idle time, the JVM needs to
> be restarted to reclaim the heap.
>
> Cheers
>>
>>    -----------------
>> Aaron Morton
>> Freelance Cassandra Consultant
>> New Zealand
>>
>> @aaronmorton
>> http://www.thelastpickle.com
>>
>> On 20/06/2013, at 6:36 AM, Wei Zhu <wz1975@yahoo.com> wrote:
>>
>> If you want, you can try to force the GC through Jconsole.
>> Memory->Perform GC.
>>
>> It theoretically triggers a full GC and when it will happen depends on
>> the JVM
>>
>> -Wei
>>
>> ------------------------------
>> *From: *"Robert Coli" <rcoli@eventbrite.com>
>> *To: *user@cassandra.apache.org
>> *Sent: *Tuesday, June 18, 2013 10:43:13 AM
>> *Subject: *Re: Heap is not released and streaming hangs at 0%
>>
>> On Tue, Jun 18, 2013 at 10:33 AM, srmore <comomore@gmail.com> wrote:
>> > But then shouldn't JVM C G it eventually ? I can still see Cassandra
>> alive
>> > and kicking but looks like the heap is locked up even after the traffic
>> is
>> > long stopped.
>>
>> No, when GC system fails this hard it is often a permanent failure
>> which requires a restart of the JVM.
>>
>> > nodetool -h localhost flush didn't do much good.
>>
>> This adds support to the idea that your heap is too full, and not full
>> of memtables.
>>
>> You could try nodetool -h localhost invalidatekeycache, but that
>> probably will not free enough memory to help you.
>>
>> =Rob
>>
>>
>>
>

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