you should check the jmx stages I posted about On Fri, May 21, 2010 at 7:05 AM, Ian Soboroff <isobor...@gmail.com> wrote: > Just an update. I rolled the memtable size back to 128MB. I am still > seeing that the daemon runs for a while with reasonable heap usage, but then > the heap climbs up to the max (6GB in this case, should be plenty) and it > starts GCing, without much getting cleared. The client catches lots of > exceptions, where I wait 30 seconds and try again, with a new client if > necessary, but it doesn't clear up. > > Could this be related to memory leak problems I've skimmed past on the list > here? > > It can't be that I'm creating rows a bit at a time... once I stick a web > page into two CFs, it's over and done with for this application. I'm just > trying to get stuff loaded. > > Is there a limit to how much on-disk data a Cassandra daemon can manage? Is > there runtime overhead associated with stuff on disk? > > Ian > > On Thu, May 20, 2010 at 9:31 PM, Ian Soboroff <isobor...@gmail.com> wrote: >> >> Excellent leads, thanks. cassandra.in.sh has a heap of 6GB, but I didn't >> realize that I was trying to float so many memtables. I'll poke tomorrow >> and report if it gets fixed. >> Ian >> >> On Thu, May 20, 2010 at 10:40 AM, Jonathan Ellis <jbel...@gmail.com> >> wrote: >>> >>> Some possibilities: >>> >>> You didn't adjust Cassandra heap size in cassandra.in.sh (1GB is too >>> small) >>> You're inserting at CL.ZERO (ROW-MUTATION-STAGE in tpstats will show >>> large pending ops -- large = 100s) >>> You're creating large rows a bit at a time and Cassandra OOMs when it >>> tries to compact (the oom should usually be in the compaction thread) >>> You have your 5 disks each with a separate data directory, which will >>> allow up to 12 total memtables in-flight internally, and 12*256 is too >>> much for the heap size you have (FLUSH-WRITER-STAGE in tpstats will >>> show large pending ops -- large = more than 2 or 3) >>> >>> On Tue, May 18, 2010 at 6:24 AM, Ian Soboroff <isobor...@gmail.com> >>> wrote: >>> > I hope this isn't too much of a newbie question. I am using Cassandra >>> > 0.6.1 >>> > on a small cluster of Linux boxes - 14 nodes, each with 8GB RAM and 5 >>> > data >>> > drives. The nodes are running HDFS to serve files within the cluster, >>> > but >>> > at the moment the rest of Hadoop is shut down. I'm trying to load a >>> > large >>> > set of web pages (the ClueWeb collection, but more is coming) and my >>> > Cassandra daemons keep dying. >>> > >>> > I'm loading the pages into a simple column family that lets me fetch >>> > out >>> > pages by an internal ID or by URL. The biggest thing in the row is the >>> > page >>> > content, maybe 15-20k per page of raw HTML. There aren't a lot of >>> > columns. >>> > I tried Thrift, Hector, and the BMT interface, and at the moment I'm >>> > doing >>> > batch mutations over Thrift, about 2500 pages per batch, because that >>> > was >>> > fastest for me in testing. >>> > >>> > At this point, each Cassandra node has between 500GB and 1.5TB >>> > according to >>> > nodetool ring. Let's say I start the daemons up, and they all go live >>> > after >>> > a couple minutes of scanning the tables. I then start my importer, >>> > which is >>> > a single Java process reading Clueweb bundles over HDFS, cutting them >>> > up, >>> > and sending the mutations to Cassandra. I only talk to one node at a >>> > time, >>> > switching to a new node when I get an exception. As the job runs over >>> > a few >>> > hours, the Cassandra daemons eventually fall over, either with no error >>> > in >>> > the log or reporting that they are out of heap. >>> > >>> > Each daemon is getting 6GB of RAM and has scads of disk space to play >>> > with. >>> > I've set the storage-conf.xml to take 256MB in a memtable before >>> > flushing >>> > (like the BMT case), and to do batch commit log flushes, and to not >>> > have any >>> > caching in the CFs. I'm sure I must be tuning something wrong. I >>> > would >>> > eventually like this Cassandra setup to serve a light request load but >>> > over >>> > say 50-100 TB of data. I'd appreciate any help or advice you can >>> > offer. >>> > >>> > Thanks, >>> > Ian >>> > >>> >>> >>> >>> -- >>> Jonathan Ellis >>> Project Chair, Apache Cassandra >>> co-founder of Riptano, the source for professional Cassandra support >>> http://riptano.com >> > >
-- Jonathan Ellis Project Chair, Apache Cassandra co-founder of Riptano, the source for professional Cassandra support http://riptano.com
