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From Jonathan Ellis <jbel...@gmail.com>
Subject Re: 0.7.2 slow memtables flushing
Date Sat, 19 Feb 2011 14:43:17 GMT
Flush code didn't change between 0.7.0 and 0.7.2. There must be some
other variable here. Memory pressure maybe?

On Sat, Feb 19, 2011 at 8:16 AM, Ivan Georgiev <yngwiie@bk.ru> wrote:
> Hi,
>
> I am testing 0.7.2 on a Windows 2003 x64 system(one node) and I am having
> the following problem.
> My insertion speed is relatively slow, so the memtables do not get full and
> the actual flushing is triggered by memtable_flush_after_mins, this happens
> on the hour mark. My problem with 0.7.2 is that when that happens, the cpu
> spikes to 25% overall usage (x4 Xeon) and the operation takes anywhere from
> 2 to 4 minutes, leaving the node not responding during that time. This has
> forced to me to increase the rpc timeout option to beyond what i feel
> comfortable with.
> I have run multiple tests with 0.7.0 and 0.7.2 with the same dataset and the
> results are consistent. During the same operation 0.7.0 takes about 10
> seconds to complete vs. 2 to 4 minutes for 0.7.2. I am attaching a log with
> the timestamps from one such flushing of 0.7.2. Please let me know if there
> is anything i can do to speed up and get results similar to 0.7.0.
>
> Regards:
> Ivan
>
> This is the log of the operations which took most time during the flush
> operation. Using 0.7.0, with the same number of operations the flushing
> takes less than 10 seconds.
>
> INFO 01:36:44,906 Enqueuing flush of
> Memtable-ArchiveFiles.6f776e65724944@1225856921(1619949 bytes, 34467
> operations)
> INFO 01:37:47,375 Completed flushing
> C:\Storage\data\Storage\ArchiveFiles.68617368-f-3-Data.db (5549187 bytes)
> INFO 01:37:47,375 Writing Memtable-ArchiveFiles.6e616d65@978152661(1619949
> bytes, 34467 operations)
> INFO 01:37:47,375 Enqueuing flush of
> Memtable-ArchiveFiles.706172656e74466f6c6465724944@2097700961(1619949 bytes,
> 34467 operations)
> INFO 01:38:51,343 Completed flushing
> C:\Storage\data\Storage\ArchiveFiles.6e616d65-f-3-Data.db (3820265 bytes)
> INFO 01:38:51,343 Writing
> Memtable-ArchiveFiles.6f776e65724944@1225856921(1619949 bytes, 34467
> operations)
>



-- 
Jonathan Ellis
Project Chair, Apache Cassandra
co-founder of DataStax, the source for professional Cassandra support
http://www.datastax.com

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