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From aaron morton <aa...@thelastpickle.com>
Subject Re: C++ Thrift client
Date Tue, 21 May 2013 08:11:30 GMT
> Aaron, whenever I get a GCInspector event log, will it means that I'm having a GC pause?
Messages about ParNew are GS pauses that went over 200ms. 
CMS GC has to relatively small pauses during it's cycle. 

All ParNew GC pauses the application threads, Cassandra is just logging the ones that take
over 200ms. If you want to see them all enable the GC logging in /etc/cassanda/cassandra-env.sh

Cheers
 
-----------------
Aaron Morton
Freelance Cassandra Consultant
New Zealand

@aaronmorton
http://www.thelastpickle.com

On 18/05/2013, at 10:29 AM, Sorin Manolache <sorinm@gmail.com> wrote:

> On 2013-05-16 02:58, Bill Hastings wrote:
>> Hi All
>> 
>> I am doing very small inserts into Cassandra in the range of say 64
>> bytes. I use a C++ Thrift client and seem consistently get latencies
>> anywhere between 35-45 ms. Could some one please advise as to what
>> might be happening?
> 
> Sniff the network traffic in order to check whether you use the same connection or you
open a new connection for each new insert.
> 
> Also check if the client does a set_keyspace (or "use keyspace") before every insert.
That would be wasteful too.
> 
> In the worst case, the client would perform an authentication too.
> 
> Inspect timestamps of the network packets in the capture file in order to determine which
part takes too long: the connection phase? The authentication? The interval between sending
the request and getting the response?
> 
> I do something similar (C++ Thrift, small inserts of roughly the same size as you) and
I get response times of 100ms for the first request when opening the connection, authentifying,
and setting the keyspace. But subsequent requests on the same connection have response times
in the range of 8-11ms.
> 
> Sorin
> 


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