Thanks, I had seen your stackoverflow post. I've got hundreds of
(wide-) rows, and the writes are pretty well distributed across them.
I'm very reluctant to drop back to the thrift interface.
On 09/11/2013 10:46 AM, Paul Cichonski wrote:
How much of the data you are writing is going against the same row key?
I've experienced some issues using CQL to write a full wide-row at once (across
multiple threads) that exhibited some of the symptoms you have described (i.e.,
high cpu, dropped mutations).
This question goes into it a bit
more:http://stackoverflow.com/questions/18522191/using-cassandra-and-cql3-how-do-you-insert-an-entire-wide-row-in-a-single-reque
. I was able to solve my issue by switching to using the thrift batch_mutate
to write a full wide-row at once instead of using many CQL INSERT statements.
-Paul
-----Original Message-----
From: Keith Freeman [mailto:8fo...@gmail.com]
Sent: Wednesday, September 11, 2013 9:16 AM
To:user@cassandra.apache.org
Subject: Re: heavy insert load overloads CPUs, with MutationStage pending
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.
