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From "Langston, Jim" <Jim.Langs...@compuware.com>
Subject read ?
Date Tue, 03 Sep 2013 13:19:51 GMT
Hi all,

Quick question

I currently am looking at a 4 node cluster and I have currently stopped all writing to
Cassandra,  with the reads continuing. I'm trying to understand the utilization
of memory within the JVM. nodetool info on each of the nodes shows them all
growing in footprint, 2 of the three at a greater rate. On the restart of Cassandra
each were at about 100MB, after 2 days, each of the following are at:

Heap Memory (MB) : 798.41 / 3052.00

Heap Memory (MB) : 370.44 / 3052.00

Heap Memory (MB) : 549.73 / 3052.00

Heap Memory (MB) : 481.89 / 3052.00

Ring configuration:

Address         Rack        Status State   Load            Owns                Token
                                                                               127605887595351923798765477786913079296
x     1d          Up     Normal  4.38 GB         25.00%              0
x   1d          Up     Normal  4.17 GB         25.00%              42535295865117307932921825928971026432
x   1d          Up     Normal  4.19 GB         25.00%              85070591730234615865843651857942052864
x   1d          Up     Normal  4.14 GB         25.00%              127605887595351923798765477786913079296


What I'm not sure of is what the growth is different between each ? and why
that growth is being created by activity that is read only.

Is Cassandra caching and holding the read data ?

I currently have caching turned off for the key/row. Also as part of the info command

Key Cache        : size 0 (bytes), capacity 0 (bytes), 0 hits, 0 requests, NaN 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



Thanks,

Jim

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