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From Thorvaldsson Justus <>
Subject SV: Help! Cassandra Data Loader threads are getting stuck
Date Tue, 27 Jul 2010 07:09:49 GMT
I made one program doing just this with Java
I read with one thread from file into an array stopping when size is 20k and w8 until it is
less than 20k and continue reading the datafile. (this is the raw data I want to move)

I have n number of threads
Each with one batch of their own and one connection to Cassandra of their own.
They fill their batch with data taking it out of the array (this is synchronized), when it
reaches 1k it sends it to Cassandra.
I had some problems but none regarding Cassandra it was my own code that faltered.
I could provide code if you want.

Från: Aaron Morton []
Skickat: den 26 juli 2010 23:32
Ämne: Re: Help! Cassandra Data Loader threads are getting stuck

Try running it without threading to see if it's a cassandra problem or an issue with your

Perhaps split the file and run many single threaded processes to load the data.


On 27 Jul, 2010,at 07:14 AM, Rana Aich <> wrote:
Hi All,

I have to load huge quantity of data into Cassandra (~10Billion rows).

I'm trying to load the Data from files using multithreading.

The idea is each thread will read the TAB delimited file and process chunk of records.

For example Thread1 reads line 1-1000 lines
Thread 2 reads line 1001-2000 and insert into Cassandra.
Thread 3 reads line 2001-3000 and insert into Cassandra.

Thread 10 reads line 9001-10000 and insert into Cassandra.
Thread 1  reads line 10001-11000 and insert into Cassandra.
Thread 2 reads line 11001-12000 and insert into Cassandra.

and so on...

I'm testing with a small file size with 200000 records.

But somehow the process gets stuck and doesn't proceed any further after processing say 16,000

I've attached my working file.

Any help will be very much appreciated.



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