Thanks for your help. Yes, I will try to increase the sstable size. I hope it can save me.
9000 SSTableReader x 10 RandomAccessReader x 64Kb = 5.6G memory. If there is only one RandomAccessReader, the memory will be 9000 * 1 * 64Kb = 0.56G . Looks great. But I think it must be reasonable to recycle the RandomAccessReader. On Mon, Jul 15, 2013 at 4:02 PM, Janne Jalkanen <janne.jalka...@ecyrd.com>wrote: > > I had exactly the same problem, so I increased the sstable size (from 5 to > 50 MB - the default 5MB is most certainly too low for serious usecases). > Now the number of SSTableReader objects is manageable, and my heap is > happier. > > Note that for immediate effect I stopped the node, removed the *.json > files and restarted - which put all SSTables to L0, which meant a weekend > full of compactions… Would be really cool if there was a way to > automatically drop all LCS SSTables one level down to make them compact > earlier without avoiding the > "OMG-must-compact-everything-aargh-my-L0-is-full" -effect of removing the > JSON file. > > /Janne > > On 15 Jul 2013, at 10:48, sulong <sulong1...@gmail.com> wrote: > > > Why does cassandra PoolingSegmentedFile recycle the RandomAccessReader? > The RandomAccessReader objects consums too much memory. > > > > I have a cluster of 4 nodes. Every node's cassandra jvm has 8G heap. The > cassandra's memory is full after about one month, so I have to restart the > 4 nodes every month. > > > > I have 100G data on every node, with LevedCompactionStrategy and 10M > sstable size, so there are more than 10000 sstable files. By looking > through the heap dump file, I see there are more than 9000 SSTableReader > objects in memory, which references lots of RandomAccessReader objects. > The memory is consumed by these RandomAccessReader objects. > > > > I see the PoolingSegementedFile has a recycle method, which puts the > RandomAccessReader to a queue. Looks like the Queue always grow until the > sstable is compacted. Is there any way to stop the RandomAccessReader > recycling? Or, set a limit to the recycled RandomAccessReader's number? > > > > > >
