This is interesting, where are you seeing that you're collecting 50% of the time? Is your env.sh the default? How much ram?
Also, can you run this tool and send a minute worth of thread info: wget https://bintray.com/artifact/download/aragozin/generic/sjk-plus-0.3.6.jar java -jar sjk-plus-0.3.6.jar ttop -s localhost:7199 -n 30 -o CPU On Sep 23, 2015 7:09 AM, "Tom van den Berge" <tom.vandenbe...@gmail.com> wrote: > I have two data centers, each with the same number of nodes, same hardware > (CPUs, memory), Cassandra version (2.1.6), replication factory, etc. The > only difference it that one data center uses vnodes, and the other doesn't. > > The non-vnode DC works fine (and has been for a long time) under > production load: I'm seeing normal CPU and IO load and garbage collection > figures. But the vnode DC is struggling very hard under the same load. It > has been set up recently. The CPU load is very high, due to excessive > garbage collection (>50% of the time is spent collecting). > > So it seems that Cassandra simply doesn't have enough memory. I'm trying > to understand if this can be caused by the use of vnodes? Is there an > sensible reason why vnodes would consume more memory than regular nodes? Or > does any of you have the same experience? If not, I might be barking up the > wrong tree here, and I would love to know it before upgrading my servers > with more memory. > > Thanks, > Tom >
