A key point in that FAQ entry is that the deletes don't occur until after the configured GCGraceSeconds (10 days is the default I believe).
This (http://wiki.apache.org/cassandra/FAQ#slows_down_after_lotso_inserts) FAQ entry mentions your scenario and suggests either increasing the memory allocation to the JVM or decreasing the insert threshold before Cassandra flushes its memtables... On Wed, Sep 22, 2010 at 5:51 PM, Chris Jansen < chris.jan...@cognitomobile.com> wrote: > Hi Dan, > > > > I do see compaction happen, I keep a close eye on the disk usage and what I > see is the usage grow then shrink, but it despite the periodic compaction > the overall result is a slow but steady growth. > > > > Regards, > > > > Chris > > > > *From:* Dan Washusen [mailto:d...@reactive.org] > *Sent:* 22 September 2010 08:39 > *To:* user@cassandra.apache.org > *Subject:* Re: Running out of heap > > > > http://wiki.apache.org/cassandra/FAQ#i_deleted_what_gives > > > > That help? > > On Wed, Sep 22, 2010 at 5:27 PM, Chris Jansen < > chris.jan...@cognitomobile.com> wrote: > > Hi all, > > > > I have written a test application that does a write, read and delete on one > of the sample column families that ship with Cassandra, and for some reason > when I leave it going for an extended period of time I see Cassandra crash > with out of heap exceptions. I don’t understand why this should be as I am > deleting the data almost as soon as I have read it. > > > > Also I am seeing the data files grow for Keyspace1, again with apparently > no reason as I am deleting the data as I read it, which eventually causes > the disk space to completely fill up. > > > > How can this be, am I using Cassandra in the wrong way or is this a bug? > > > > Any help or advice would be greatly appreciated. > > > > Thanks in advance, > > > > Chris > > > > > > PS To give a better idea of what I am doing I’ve included some of the > source from my Java test app, typically I have 20 threads running in > parallel performing this operation: > > > > while(true) > > { > > long startTime = System.currentTimeMillis(); > > key = UUID.randomUUID().toString(); > > long timestamp = System.currentTimeMillis(); > > ColumnPath colPathFdl = new ColumnPath(columnFamily); > > > colPathFdl.setColumn(("345345345354"+key).getBytes(UTF8)); > > > > boolean broken = true; > > > > while(broken) > > { > > try > > { > > client.insert(keyspace, key, colPathFdl, > getBytesFromFile(new > File("/opt/java/apache-cassandra/conf/storage-conf.xml")),timestamp, > ConsistencyLevel.QUORUM); > > broken = false; > > } > > catch(Exception e) > > { > > System.out.println("Cannot write: "+key+" > RETRYING"); > > broken=true; > > e.printStackTrace(); > > } > > } > > > > try > > { > > Column col = client1.get(keyspace, key, > colPathFdl,ConsistencyLevel.QUORUM).getColumn(); > > System.out.println(key +" column name: " + new > String(col.name, UTF8)); > > //System.out.println("column value: " + new > String(col.value, UTF8)); > > System.out.println(key +" column timestamp: " + new > Date(col.timestamp)); > > > > } > > catch(Exception e) > > { > > System.out.println("Cannot read: "+key); > > e.printStackTrace(); > > } > > > > try > > { > > System.out.println(key +" delete column:: "+key); > > client.remove(keyspace, key, colPathFdl, timestamp, > ConsistencyLevel.QUORUM); > > } > > catch(Exception e) > > { > > System.out.println("Cannot delete: "+key); > > e.printStackTrace(); > > } > > > > long stopTime = System.currentTimeMillis(); > > long timeTaken = stopTime -startTime; > > System.err.println(Thread.currentThread().getName() + > " " +key+ " Last operation took "+ timeTaken+"ms" ); > > } > > > > > > > NOTICE: Cognito Limited. Benham Valence, Newbury, Berkshire, RG20 8LU. UK. > Company number 02723032. This e-mail message and any attachment is > confidential. It may not be disclosed to or used by anyone other than the > intended recipient. If you have received this e-mail in error please notify > the sender immediately then delete it from your system. Whilst every effort > has been made to check this mail is virus free we accept no responsibility > for software viruses and you should check for viruses before opening any > attachments. Opinions, conclusions and other information in this email and > any attachments which do not relate to the official business of the company > are neither given by the company nor endorsed by it. > > This email message has been scanned for viruses by > Mimecast<http://www.mimecast.com> > > >
