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Posted to user@cassandra.apache.org by "yue.zhang" <yu...@chinacache.com> on 2013/06/27 03:14:21 UTC
答复: about FlushWriter "All time blocked"
This means there were 12 times the code wanted to put an memtable in the queue to be flushed to disk but the queue was full.
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seem not a serious problem. what's the different between 'Blocked' and 'All time blocked'.
thx
-heipark
-----邮件原件-----
发件人: aaron morton [mailto:aaron@thelastpickle.com]
发送时间: 2013年6月26日 13:29
收件人: user@cassandra.apache.org
主题: Re: about FlushWriter "All time blocked"
> FlushWriter 0 0 191 0 12
This means there were 12 times the code wanted to put an memtable in the queue to be flushed to disk but the queue was full.
The length of this queue is controlled by the memtable_flush_queue_size https://github.com/apache/cassandra/blob/cassandra-1.2/conf/cassandra.yaml#L299 and memtable_flush_writers .
When this happens an internal lock around the commit log is held which prevents writes from being processed.
In general it means the IO system cannot keep up. It can sometimes happen when snapshot is used as all the CF's are flushed to disk at once. I also suspect it happens sometimes when a commit log segment is flushed and their are a lot of dirty CF's. But i've never proved it.
Increase memtable_flush_queue_size following the help in the yaml file. If you do not use secondary indexes are you using snapshot?
Hope that helps.
A
-----------------
Aaron Morton
Freelance Cassandra Consultant
New Zealand
@aaronmorton
http://www.thelastpickle.com
On 24/06/2013, at 3:41 PM, yue.zhang <yu...@chinacache.com> wrote:
> 3 node
> cent os
> CPU 8core memory 32GB
> cassandra 1.2.5
> my scenario: many counter incr, every node has one client program, performance is 400 wps /every clicent (it’s so slowly)
>
> my question：
> Ø nodetool tpstats
> ---------------------------------
> Pool Name Active Pending Completed Blocked All time blocked
> ReadStage 0 0 8453 0 0
> RequestResponseStage 0 0 138303982 0 0
> MutationStage 0 0 172002988 0 0
> ReadRepairStage 0 0 0 0 0
> ReplicateOnWriteStage 0 0 82246354 0 0
> GossipStage 0 0 1052389 0 0
> AntiEntropyStage 0 0 0 0 0
> MigrationStage 0 0 0 0 0
> MemtablePostFlusher 0 0 670 0 0
> FlushWriter 0 0 191 0 12
> MiscStage 0 0 0 0 0
> commitlog_archiver 0 0 0 0 0
> InternalResponseStage 0 0 0 0 0
> HintedHandoff 0 0 56 0 0
> -----------------------------------
> FlushWriter “All time blocked”=12，I restart the node，but no use，it’s normally ?
>
> thx
>
> -heipark
>
>