Isnt setting swappiness to a lower value a good idea only if you know you have the physical RAM to support it? What Im observing on my box is that jsvc uses up all the physical RAM. Its VM size is 4-5GB right now (not sure if it will continue to grow).
Apologies if Im misunderstanding how the swappiness factor works...its new to me. Kyusik Chung On Apr 28, 2010, at 3:28 PM, Time Less wrote: > This sounds similar to /proc/sys/vm/swappiness misconfiguration. Is it zero > or close to zero? If setting it 0 solves your problem, make sure all your > nodes get this: > > /etc/sysctl.conf: > vm.swappiness=0 > > > On Wed, Apr 28, 2010 at 12:12 PM, Kyusik Chung <kyu...@discovereads.com> > wrote: > Hello. I am using Cassandra 0.6.1 on ubuntu 8.04. 3 node cluster. > > I notice that when I start making lots of read requests (serially), memory > usage of jsvc keeps climbing until it uses up all memory on the server > (happens for all 3 servers in the cluster). At that point, the box starts > swapping a little (but not too much) and performance is degraded. Read > performance does not drop off a cliff, but it does take a serious hit (maybe > 50%). > > I have tried setting Xmx to various different values, but it doesnt seem to > limit the growth in memory usage. I understand that I should expect to see > jsvc use a bit more memory than what the jvm is configured to use, but it > doesnt seem to be limited to just an overhead. I have set Xmx all the way > down to 128M (just to test) and still jsvc will use up 2G of memory. > > Are there other settings that I should be changing? > > Note that when I test by simply running a lot of writes but no reads, jsvc > seems to respect the Xmx value. > > Thanks! > > Kyusik Chung > > -- > timeless(ness)
