On Tue, Nov 4, 2014 at 8:51 PM, Raj N <raj.cassan...@gmail.com> wrote:
> Is there a good formula to calculate heap utilization in Cassandra > pre-1.1, specifically 1.0.10. We are seeing gc pressure on our nodes. And I > am trying to estimate what could be causing this? Using node tool info my > steady state heap is at about 10GB. XMX is 12G. > Basically, no. If you really want to know, take a heap dump and load it into Eclipse Memory Analyzer. > I have 4.5 GB of bloom filters which I can derive looking at cfstats > This is a *very* large percentage of your total heap, and is probably the lever you have most influence on pulling. > I have negligible row caching. > Row caching is generally not advised in that era, especially with heap pressure. > I have key caching enabled on my cfs. I couldn't find an easy way to > estimate how much this is using, but I tried to invalidate the key cache > and I got 1.3 GB back. > Key caching is generally advisable, but 1.3GB is a lot of key cache.. > That still only adds up to 5.8 GB. I know there is index sampling going on > as well. I have around 800 million rows. Is there a way to estimate how > much space this would add up to? > Plenty. You should reduce your bloom filter size, or upgrade to a version of Cassandra that moves stuff off the heap. =Rob http://twitter.com/rcolidba
