heap usage

[Reik Schatz <re...@gmail.com>]

Hi,

recently we are hitting some OOM: Java heap space, so I was investigating
how the heap is used in Cassandra 1.2+

We use the calculated 4G heap. Our cluster is 6 nodes, around 750 GB data
and a replication factor of 3. Row cache is disabled. All key cache and
memtable settings are left at default.

Is the primary key index kept in heap memory? We have a bunch of keyspaces
and column families.

Thanks,
Rik

Re: heap usage

[Bryan Talbot <bt...@aeriagames.com>]

Aren't bloom filters kept off heap in 1.2?
https://issues.apache.org/jira/browse/CASSANDRA-4865

Disabling bloom filters also disables tombstone removal as well, so don't
disable them if you delete anything.

https://issues.apache.org/jira/browse/CASSANDRA-5182

I believe that the index samples (by default every 128th entry) are still
kept in in memory so your JVM memory will scale with the number of rows
stored.  Additional memory is used for every keyspace and CF too so if you
have thousands of CF that could be an issue.

-Bryan



On Fri, Feb 15, 2013 at 8:16 AM, Edward Capriolo <ed...@gmail.com>wrote:

> It is not going to be true for long that LCS does not require bloom
> filters.
>
> https://issues.apache.org/jira/browse/CASSANDRA-5029
>
> Apparently, without bloom filters there are issues.
>
> On Fri, Feb 15, 2013 at 7:29 AM, Blake Manders <bl...@crosspixel.net>
> wrote:
> >
> > You probably want to look at your bloom filters.  Be forewarned though,
> > they're difficult to change; changes to bloom filter settings only apply
> to
> > new SSTables, so they might not be noticeable until a few compactions
> have
> > taken place.
> >
> > If that is your issue, and your usage model fits it, a good alternative
> to
> > the slow propagation of higher miss rates is to switch to LCS (which
> doesn't
> > use bloom filters), which won't require you to make the jump to 1.2.
> >
> >
> > On Fri, Feb 15, 2013 at 4:06 AM, Reik Schatz <re...@gmail.com>
> wrote:
> >>
> >> Hi,
> >>
> >> recently we are hitting some OOM: Java heap space, so I was
> investigating
> >> how the heap is used in Cassandra 1.2+
> >>
> >> We use the calculated 4G heap. Our cluster is 6 nodes, around 750 GB
> data
> >> and a replication factor of 3. Row cache is disabled. All key cache and
> >> memtable settings are left at default.
> >>
> >> Is the primary key index kept in heap memory? We have a bunch of
> keyspaces
> >> and column families.
> >>
> >> Thanks,
> >> Rik
> >
> >
> >
> >
> > --
> >
> > Blake Manders | CTO
> >
> > Cross Pixel, Inc. | 494 8th Ave, Penthouse | NYC 10001
> >
> > Website: crosspixel.net
> > Twitter: twitter.com/CrossPix
>

Re: heap usage

[Edward Capriolo <ed...@gmail.com>]

It is not going to be true for long that LCS does not require bloom filters.

https://issues.apache.org/jira/browse/CASSANDRA-5029

Apparently, without bloom filters there are issues.

On Fri, Feb 15, 2013 at 7:29 AM, Blake Manders <bl...@crosspixel.net> wrote:
>
> You probably want to look at your bloom filters.  Be forewarned though,
> they're difficult to change; changes to bloom filter settings only apply to
> new SSTables, so they might not be noticeable until a few compactions have
> taken place.
>
> If that is your issue, and your usage model fits it, a good alternative to
> the slow propagation of higher miss rates is to switch to LCS (which doesn't
> use bloom filters), which won't require you to make the jump to 1.2.
>
>
> On Fri, Feb 15, 2013 at 4:06 AM, Reik Schatz <re...@gmail.com> wrote:
>>
>> Hi,
>>
>> recently we are hitting some OOM: Java heap space, so I was investigating
>> how the heap is used in Cassandra 1.2+
>>
>> We use the calculated 4G heap. Our cluster is 6 nodes, around 750 GB data
>> and a replication factor of 3. Row cache is disabled. All key cache and
>> memtable settings are left at default.
>>
>> Is the primary key index kept in heap memory? We have a bunch of keyspaces
>> and column families.
>>
>> Thanks,
>> Rik
>
>
>
>
> --
>
> Blake Manders | CTO
>
> Cross Pixel, Inc. | 494 8th Ave, Penthouse | NYC 10001
>
> Website: crosspixel.net
> Twitter: twitter.com/CrossPix

Re: heap usage

[Blake Manders <bl...@crosspixel.net>]

You probably want to look at your bloom filters.  Be forewarned though,
they're difficult to change; changes to bloom filter settings only apply to
new SSTables, so they might not be noticeable until a few compactions have
taken place.

If that is your issue, and your usage model fits it, a good alternative to
the slow propagation of higher miss rates is to switch to LCS (which
doesn't use bloom filters), which won't require you to make the jump to 1.2.


On Fri, Feb 15, 2013 at 4:06 AM, Reik Schatz <re...@gmail.com> wrote:

> Hi,
>
> recently we are hitting some OOM: Java heap space, so I was investigating
> how the heap is used in Cassandra 1.2+
>
> We use the calculated 4G heap. Our cluster is 6 nodes, around 750 GB data
> and a replication factor of 3. Row cache is disabled. All key cache and
> memtable settings are left at default.
>
> Is the primary key index kept in heap memory? We have a bunch of keyspaces
> and column families.
>
> Thanks,
> Rik
>



-- 

*Blake Manders** |** **CTO*****

Cross Pixel, Inc. *| *494 8th Ave, Penthouse *| *NYC 10001

Website: crosspixel.ne <http://www.crosspixel.net/>t<http://www.crosspixel.net/>
Twitter: twitter.com/CrossPix