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From <moshe.kr...@barclays.com>
Subject RE: About the heap
Date Wed, 13 Mar 2013 17:28:58 GMT
Peaks may be occurring during compaction, when Sstable files are memmapped.
If so: Upgrading to C* 1.2 may bring some relief: You can trigger minor compaction on an individual
SStable file when the percentage of tombstones in that Sstable crosses a user-defined threshold.
(Aaron, can you confirm?)

From: Alain RODRIGUEZ [mailto:arodrime@gmail.com]
Sent: Wednesday, March 13, 2013 7:11 PM
To: 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

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