"You can trigger minor compaction on an individual SStable file when the percentage of tombstones in that Sstable crosses a user-defined threshold."

We have just one cf with TTL. I don't think the problem comes from there.

"Peaks may be occurring during compaction, when Sstable files are memmapped."

Ok, but why am I always running between 4 and 6 GB heap used, even when there is no traffic ?


2013/3/13 Alain RODRIGUEZ <arodrime@gmail.com>
"called index_interval set to 128"

I think this is for BloomFilters actually.


2013/3/13 Hiller, Dean <Dean.Hiller@nrel.gov>

Going to 1.2.2 helped us quite a bit as well as turning on LCS from STCS which gave us smaller bloomfilters.

As far as key cache.  There is an entry in cassandra.yaml called index_interval set to 128.  I am not sure if that is related to key_cache.  I think it is.  By turning that to 512 or maybe even 1024, you will consume less ram there as well though I ran this test in QA and my key cache size stayed the same so I am really not sure(I am actually checking out cassandra code now to dig a little deeper into this property.

Dean

From: Alain RODRIGUEZ <arodrime@gmail.com<mailto:arodrime@gmail.com>>
Reply-To: "user@cassandra.apache.org<mailto:user@cassandra.apache.org>" <user@cassandra.apache.org<mailto:user@cassandra.apache.org>>
Date: Wednesday, March 13, 2013 10:11 AM
To: "user@cassandra.apache.org<mailto:user@cassandra.apache.org>" <user@cassandra.apache.org<mailto:user@cassandra.apache.org>>
Subject: About the heap

Hi,

I would like to know everything that is in the heap.

We are here speaking of C*1.1.6

Theory :

- Memtable (1024 MB)
- Key Cache (100 MB)
- Row Cache (disabled, and serialized with JNA activated anyway, so should be off-heap)
- BloomFilters (about 1,03 GB - from cfstats, adding all the "Bloom Filter Space Used" and considering they are showed in Bytes - 1103765112)
- Anything else ?

So my heap should be fluctuating between 1,15 GB and 2.15 GB and growing slowly (from the new BF of my new data).

My heap is actually changing from 3-4 GB to 6 GB and sometimes growing to the max 8 GB (crashing the node).

Because of this I have an unstable cluster and have no other choice than use Amazon EC2 xLarge instances when we would rather use twice more EC2 Large nodes.

What am I missing ?

Practice :

Is there a way not inducing any load and easy to do to dump the heap to analyse it with MAT (or anything else that you could advice) ?

Alain