I am using C*1.1.6.

"Did you restart the node after changing the row_cache_size_in_mb ?"

No, I didn't. I used the nodetool setcachecapacity and didn't restart the node.

"The changes in GC activity are not huge and may not be due to cache activity"

I find them hudge, and just happened on the node in which I had enabled row cache. I just enabled it on .164 node from 10:45 to 10:48 and the heap size doubled from 3.5GB to 7GB (out of 8, which induced memory pressure). About GC, all the collections increased a lot compare to the other nodes with row caching disabled.

"What is the output from nodetool info?"

I can give it to you but, row cache i now disabled.

Token            : 85070591730234615865843651857942052864
Gossip active    : true
Thrift active    : true
Load             : 201.61 GB
Generation No    : 1362749056
Uptime (seconds) : 328675
Heap Memory (MB) : 5157.58 / 8152.00
Data Center      : eu-west
Rack             : 1b
Exceptions       : 24
Key Cache        : size 104857584 (bytes), capacity 104857584 (bytes), 106814132 hits, 120131310 requests, 0.858 recent hit rate, 14400 save period in seconds
Row Cache        : size 0 (bytes), capacity 0 (bytes), 0 hits, 0 requests, NaN recent hit rate, 0 save period in seconds

I think it won't help, but I can't try things now unless we are quire sure it will work smooth, we are on heavy load.

Anyway, thanks for trying to help once again.

2013/3/12 aaron morton <aaron@thelastpickle.com>
What version are you using?

Sounds like you have configured it correctly. Did you restart the node after changing the row_cache_size_in_mb ?
The changes in GC activity are not huge and may not be due to cache activity. Have they continued after you enabled the row cache?

What is the output from nodetool info?


Aaron Morton
Freelance Cassandra Consultant
New Zealand


On 11/03/2013, at 5:30 AM, Sávio Teles <savio.teles@lupa.inf.ufg.br> wrote:

I have the same problem!

2013/3/11 Alain RODRIGUEZ <arodrime@gmail.com>
I can add that I have JNA corectly loaded, from the logs: "JNA mlockall successful"

2013/3/11 Alain RODRIGUEZ <arodrime@gmail.com>
Any clue on this ?

Row cache well configured could avoid us a lot of disk read, and IO is definitely our bottleneck... If someone could explain why the row cache has so much impact on my JVM and how to avoid it, it would be appreciated :).

2013/3/8 Alain RODRIGUEZ <arodrime@gmail.com>

We have some issue having a high read throughput. I wanted to alleviate things by turning the row cache ON.

I set the row cache to 200 on one node and enable caching 'ALL' on the 3 most read CF. There is the effect this operation had on my JVM: http://img692.imageshack.us/img692/4171/datastaxopscenterr.png

It looks like the row cache was somehow stored in-heap. I looked at my cassandra.yaml and I have the following configuration: row_cache_provider: SerializingCacheProvider (which should be enough to store row cache off-heap as described above in this file: "SerializingCacheProvider serialises the contents of the row and stores it in native memory, i.e., off the JVM Heap")

What's wrong ?

Sávio S. Teles de Oliveira
voice: +55 62 9136 6996
Mestrando em Ciências da Computação - UFG
Arquiteto de Software
Laboratory for Ubiquitous and Pervasive Applications (LUPA) - UFG