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Posted to user@cassandra.apache.org by onmstester onmstester <on...@zoho.com> on 2021/11/15 06:00:38 UTC

gc throughput

Hi, 

We are using Apache Cassandra 3.11.2 with its default gc configuration (CMS and ...) on a 16GB heap, i inspected gc logs using gcviewer and it reported 92% of throughput, is that means not necessary to do any further tuning for gc? and everything is ok with gc of Cassandra?





Sent using https://www.zoho.com/mail/

Re: gc throughput

Posted by Kiran mk <co...@gmail.com>.
G1GC would be the most suitable option and it has better control over
pauses and optimal.

Best Regards,
Kiran M K

On Wed, Nov 17, 2021, 10:27 PM Elliott Sims <el...@backblaze.com> wrote:

> CMS has a higher risk of a long stop-the-world full GC that will cause a
> burst of timeouts, but if you're not getting that or don't mind if it
> happens now and then CMS is probably the way to go.  It's generally
> lower-overhead than G1.  If  you really don't care about latency it might
> even be worth testing the Parallel collector, but at 16GB there might be
> timeouts.
>
> On Wed, Nov 17, 2021 at 6:25 AM onmstester onmstester <on...@zoho.com>
> wrote:
>
>> Thank You
>> I'm going to achieve the most possible (write) throughput with Cassandra
>> and care less about latency, recommendations from community suggests that
>> better to use G1GC with 16GB heap, but when i already got 92% throughput
>> with CMS, should i consider changing it?
>>
>> Sent using Zoho Mail <https://www.zoho.com/mail/>
>>
>>
>> ---- On Tue, 16 Nov 2021 16:52:29 +0330 *Bowen Song <bowen@bso.ng
>> <bo...@bso.ng>>* wrote ----
>>
>> Do you have any performance issues? such as long STW GC pauses or high
>> p99.9 latency? If not, then you shouldn't tune the GC for the sake of it.
>> However, if you do have performance issues related to GC, regardless what
>> is the GC metric you are looking at saying, you will need to address the
>> issue and that probably will involve some GC tunings.
>> On 15/11/2021 06:00, onmstester onmstester wrote:
>>
>> Hi,
>> We are using Apache Cassandra 3.11.2 with its default gc configuration
>> (CMS and ...) on a 16GB heap, i inspected gc logs using gcviewer and it
>> reported 92% of throughput, is that means not necessary to do any further
>> tuning for gc? and everything is ok with gc of Cassandra?
>>
>>
>> Sent using Zoho Mail <https://www.zoho.com/mail/>
>>
>>
>>
>>
>>

Re: gc throughput

Posted by Elliott Sims <el...@backblaze.com>.
CMS has a higher risk of a long stop-the-world full GC that will cause a
burst of timeouts, but if you're not getting that or don't mind if it
happens now and then CMS is probably the way to go.  It's generally
lower-overhead than G1.  If  you really don't care about latency it might
even be worth testing the Parallel collector, but at 16GB there might be
timeouts.

On Wed, Nov 17, 2021 at 6:25 AM onmstester onmstester <on...@zoho.com>
wrote:

> Thank You
> I'm going to achieve the most possible (write) throughput with Cassandra
> and care less about latency, recommendations from community suggests that
> better to use G1GC with 16GB heap, but when i already got 92% throughput
> with CMS, should i consider changing it?
>
> Sent using Zoho Mail <https://www.zoho.com/mail/>
>
>
> ---- On Tue, 16 Nov 2021 16:52:29 +0330 *Bowen Song <bowen@bso.ng
> <bo...@bso.ng>>* wrote ----
>
> Do you have any performance issues? such as long STW GC pauses or high
> p99.9 latency? If not, then you shouldn't tune the GC for the sake of it.
> However, if you do have performance issues related to GC, regardless what
> is the GC metric you are looking at saying, you will need to address the
> issue and that probably will involve some GC tunings.
> On 15/11/2021 06:00, onmstester onmstester wrote:
>
> Hi,
> We are using Apache Cassandra 3.11.2 with its default gc configuration
> (CMS and ...) on a 16GB heap, i inspected gc logs using gcviewer and it
> reported 92% of throughput, is that means not necessary to do any further
> tuning for gc? and everything is ok with gc of Cassandra?
>
>
> Sent using Zoho Mail <https://www.zoho.com/mail/>
>
>
>
>
>

Re: gc throughput

Posted by onmstester onmstester <on...@zoho.com>.
Thank You

I'm going to achieve the most possible (write) throughput with Cassandra and care less about latency, recommendations from community suggests that better to use G1GC with 16GB heap, but when i already got 92% throughput with CMS, should i consider changing it?



Sent using https://www.zoho.com/mail/






---- On Tue, 16 Nov 2021 16:52:29 +0330 Bowen Song <bo...@bso.ng> wrote ----



Do you have any performance issues? such as long STW GC pauses or
      high p99.9 latency? If not, then you shouldn't tune the GC for the
      sake of it. However, if you do have performance issues related to
      GC, regardless what is the GC metric you are looking at saying,
      you will need to address the issue and that probably will involve
      some GC tunings.

On 15/11/2021 06:00, onmstester
      onmstester wrote:

Hi, 

We are using Apache Cassandra 3.11.2 with its default gc
          configuration (CMS and ...) on a 16GB heap, i inspected gc
          logs using gcviewer and it reported 92% of throughput, is that
          means not necessary to do any further tuning for gc? and
          everything is ok with gc of Cassandra?





Sent using https://www.zoho.com/mail/

Re: gc throughput

Posted by Bowen Song <bo...@bso.ng>.
Do you have any performance issues? such as long STW GC pauses or high 
p99.9 latency? If not, then you shouldn't tune the GC for the sake of 
it. However, if you do have performance issues related to GC, regardless 
what is the GC metric you are looking at saying, you will need to 
address the issue and that probably will involve some GC tunings.

On 15/11/2021 06:00, onmstester onmstester wrote:
> Hi,
> We are using Apache Cassandra 3.11.2 with its default gc configuration 
> (CMS and ...) on a 16GB heap, i inspected gc logs using gcviewer and 
> it reported 92% of throughput, is that means not necessary to do any 
> further tuning for gc? and everything is ok with gc of Cassandra?
>
>
> Sent using Zoho Mail <https://www.zoho.com/mail/>
>
>
>