We are doing some testing (Cassandra 0.7beta1)on a 3 node cluster running on Windows to see if we can use Cassandra with our application:
We are writing using Node1 with 600 row (60 columns per row) per second, ~3K size rows.
and reading from Node2 10 seconds worth of data every 60 seconds.

I see a spike in heap memory usage on Node 2 where it goes from around 1G to 6GB (max) in less than an hour, and then goes our of memory.
There are some errors in the log file that are reported by other people, but I don't think that these errors are the reason, because it use to happen even before I have seen them.

Can someone help me understand whats going on??

Attached is the log file.

and here is the JAVA options in the cassandra.bat
============
REM ***** JAVA options *****

set JAVA_OPTS=^
 -ea^
 -Xdebug^
 -Xrunjdwp:transport=dt_socket,server=y,address=8888,suspend=n^
 -Xms128m^
 -Xmx6G^
 -XX:TargetSurvivorRatio=90^
 -XX:+AggressiveOpts^
 -XX:+UseParNewGC^
 -XX:+UseConcMarkSweepGC^
 -XX:+CMSParallelRemarkEnabled^
 -XX:+HeapDumpOnOutOfMemoryError^
 -XX:SurvivorRatio=8^
 -XX:MaxTenuringThreshold=1^
 -XX:CMSInitiatingOccupancyFraction=80^
 -Dcom.sun.management.jmxremote.port=8080^
 -Dcom.sun.management.jmxremote.ssl=false^
 -Dcom.sun.management.jmxremote.authenticate=false
 

Regards,
-- 
Alaa Zubaidi