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From Dan Washusen <...@reactive.org>
Subject Re: Running out of heap
Date Wed, 22 Sep 2010 08:10:53 GMT
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.jansen@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:dan@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.jansen@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" );
>
>                 }
>
>
>
>
>
>
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