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From Keith Freeman <8fo...@gmail.com>
Subject Re: heavy insert load overloads CPUs, with MutationStage pending
Date Wed, 11 Sep 2013 16:16:01 GMT

On 09/10/2013 11:42 AM, Nate McCall wrote:
> With SSDs, you can turn up memtable_flush_writers - try 3 initially (1 
> by default) and see what happens. However, given that there are no 
> entries in 'All time blocked' for such, they may be something else.
Tried that, it seems to have reduced the loads a little after everything 
warmed-up, but not much.
>
> How are you inserting the data?

A java client on a separate box using the datastax java driver, 48 
threads writing 100 records each iteration as prepared batch statements.

At 5000 records/sec, the servers just can't keep up, so the client backs 
up.  That's only 5M of data/sec, which doesn't seem like much.  As I 
mentioned, switching to SSDs didn't help much, so I'm assuming at this 
point that the server overloads are what's holding up the client.

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