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From S G <sg.online.em...@gmail.com>
Subject Re: How can I scale my read rate?
Date Sun, 19 Mar 2017 01:54:50 GMT
Forgot to mention that this vmstat picture is for the client-cluster
reading from Cassandra.

On Sat, Mar 18, 2017 at 6:47 PM, S G <sg.online.email@gmail.com> wrote:

> ok, I gave the executeAsync() a try.
> Good part is that it was really easy to write the code for that.
> Bad part is that it did not had a huge effect on my throughput - I gained
> about 5% increase in throughput.
> I suspect it is so because my queries are all get-by-primary-key queries
> and were anyways completing in less than 2 milliseconds.
> So there was not much wait to begin with.
>
>
> Here is my code:
>
> String getByKeyQueryStr = "Select * from fooTable where key = " + key;
> //ResultSet result = session.execute(getByKeyQueryStr);  // Previous code
> ResultSetFuture future = session.executeAsync(getByKeyQueryStr);
> FutureCallback<ResultSet> callback = new MyFutureCallback();
> executor = MoreExecutors.sameThreadExecutor();
> //executor = Executors.newFixedThreadPool(3); // Tried this too, no effect
> //executor = Executors.newFixedThreadPool(10); // Tried this too, no
> effect
> Futures.addCallback(future, callback, executor);
>
> Can I improve the above code in some way?
> Are there any JMX metrics that can tell me what's going on?
>
> From the vmstat command, I see that CPU idle time is about 70% even though
> I am running about 60 threads per VM
> Total 20 client-VMs with 8 cores each are querying a Cassandra cluster
> with 16 VMs, 8-core each too.
>
>
> ​
> ​
>
>
> Thanks
> SG
>
>
> On Sat, Mar 18, 2017 at 5:38 PM, S G <sg.online.email@gmail.com> wrote:
>
>> Thanks. It seems that you guys have found executeAsync to yield good
>> results.
>> I want to share my understanding how this could benefit performance and
>> some validation from the group will be awesome.
>>
>> I will call executeAsync() each time I want to get by primary-key.
>> That ways, my client thread is not blocked anymore and I can submit a lot
>> more requests per unit time.
>> The async requests get piled on the underlying Netty I/O thread which
>> ensures that it is always busy all the time.
>> Earlier, the Netty I/O thread would have wasted some cycles when the
>> sync-execute method was processing the results.
>> And earlier, the client thread would also have wasted some cycles waiting
>> for netty-thread to complete.
>>
>> With executeAsync(), none of them is waiting.
>> Only thing to ensure is that the Netty thread's queue does not grow
>> indefinitely.
>>
>> If the above theory is correct, then it sounds like a really good thing
>> to try.
>> If not, please do share some more details.
>>
>>
>>
>>
>> On Sat, Mar 18, 2017 at 2:00 PM, <j.kesten@enercast.de> wrote:
>>
>>> +1 for executeAsync – had a long time to argue that it’s not bad as with
>>> good old rdbms.
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>> Gesendet von meinem Windows 10 Phone
>>>
>>>
>>>
>>> *Von: *Arvydas Jonusonis <arvydas.jonusonis@gmail.com>
>>> *Gesendet: *Samstag, 18. März 2017 19:08
>>> *An: *user@cassandra.apache.org
>>> *Betreff: *Re: How can I scale my read rate?
>>>
>>>
>>>
>>> ..then you're not taking advantage of request pipelining. Use
>>> executeAsync - this will increase your throughput for sure.
>>>
>>>
>>>
>>> http://www.datastax.com/dev/blog/java-driver-async-queries
>>>
>>>
>>>
>>>
>>>
>>> On Sat, Mar 18, 2017 at 08:00 S G <sg.online.email@gmail.com> wrote:
>>>
>>> I have enabled JMX but not sure what metrics to look for - they are way
>>> too many of them.
>>>
>>> I am using session.execute(...)
>>>
>>>
>>>
>>>
>>>
>>> On Fri, Mar 17, 2017 at 2:07 PM, Arvydas Jonusonis <
>>> arvydas.jonusonis@gmail.com> wrote:
>>>
>>> It would be interesting to see some of the driver metrics (in your
>>> stress test tool) - if you enable JMX, they should be exposed by default.
>>>
>>> Also, are you using session.execute(..) or session.executeAsync(..) ?
>>>
>>>
>>>
>>>
>>>
>>
>

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