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From "Hiller, Dean" <>
Subject Re: About the heap
Date Wed, 13 Mar 2013 18:11:14 GMT
Going to 1.2.2 helped us quite a bit as well as turning on LCS from STCS which gave us smaller

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.


From: Alain RODRIGUEZ <<>>
Reply-To: "<>" <<>>
Date: Wednesday, March 13, 2013 10:11 AM
To: "<>" <<>>
Subject: About the heap


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) ?


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