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From aaron morton <aa...@thelastpickle.com>
Subject Re: Digest Query Seems to be corrupt on certain cases
Date Thu, 28 Mar 2013 03:06:20 GMT
> We started receiving OOMs in our cassandra grid and took a heap dump
What are the JVM settings ? 
What was the error stack? 

> I am pasting the serialized byte array of SliceByNamesReadCommand, which seems to be
corrupt on issuing certain digest queries.
Sorry I don't follow what you are saying here. 
Can you can you enable DEBUG logging and identify the behaviour you think is incorrect ?

Cheers

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

@aaronmorton
http://www.thelastpickle.com

On 28/03/2013, at 4:15 AM, Ravikumar Govindarajan <ravikumar.govindarajan@gmail.com>
wrote:

> We started receiving OOMs in our cassandra grid and took a heap dump. We are running
version 1.0.7 with LOCAL_QUORUM from both reads/writes.
> 
> After some analysis, we kind of identified the problem, with SliceByNamesReadCommand,
involving a single Super-Column. This seems to be happening only in digest query and not during
actual reads.
> 
> I am pasting the serialized byte array of SliceByNamesReadCommand, which seems to be
corrupt on issuing certain digest queries.
> 
> 		//Type is SliceByNamesReadCommand
> 		body[0] = (byte)1;
> 		
> 		//This is a digest query here.
> 		body[1] = (byte)1;
> 
>                 //Table-Name from 2-8 bytes
> 
>                 //Key-Name from 9-18 bytes
> 
>                 //QueryPath deserialization here
>              
>                      //CF-Name from 19-30 bytes
> 
>                     //Super-Col-Name from 31st byte onwards, but gets corrupt as found
in heap dump
> 
>                     //body[32-37] = 0, body[38] = 1, body[39] = 0.  This causes the SliceByNamesDeserializer
to mark both ColName=NULL and SuperColName=NULL, fetching entire wide-row!!!
> 
>                    //Actual super-col-name starts only from byte 40, whereas it should
have started from 31st byte itself
> 
> Has someone already encountered such an issue? Why is the super-col-name not correctly
de-serialized during digest query.
> 
> --
> Ravi
> 


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