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From aaron morton <aa...@thelastpickle.com>
Subject Re: 33million hinted handoffs from nowhere
Date Mon, 18 Mar 2013 16:51:35 GMT
You can check which nodes hints are being held for using the JMX api. Look for the org.apache.cassandra.db:type=HintedHandoffManager
MBean and call the listEndpointsPendingHints() function. 

There are two points where hints may be stored, if the node is down when the request started
or if the node timed out and did not return before rpc_timeout. To check for the first, look
for log lines about a node being "dead" on the coordinator. To check for the second look for
dropped messages on the other nodes. This will be logged, or you can use nodetool tpstats
to look for them.

Cheers
  
-----------------
Aaron Morton
Freelance Cassandra Consultant
New Zealand

@aaronmorton
http://www.thelastpickle.com

On 15/03/2013, at 2:30 AM, Andras Szerdahelyi <andras.szerdahelyi@ignitionone.com> wrote:

> ( The previous letter was sent prematurely, sorry. )
> 
> This node is the only node being written to, but the Cfs being written replicate to almost
all of the other nodes
> My understanding is that hinted handoff is mutations kept around on the coordinator node,
to be replayed when the target node re-appears on the ring. All my nodes are up and again,
no hinted handoff is logged on the node itself
> 
> Thanks!
> Andras
> 
> From: Andras Szerdahelyi <andras.szerdahelyi@ignitionone.com>
> Date: Thursday 14 March 2013 14:25
> To: "user@cassandra.apache.org" <user@cassandra.apache.org>
> Subject: 33million hinted handoffs from nowhere
> 
> Hi list,
> 
> I am experiencing seemingly uncontrollable and unexplained growth of my HintedHandoff
CF on a single node. Unexplained because there are no hinted handoffs being logged on the
node, uncontrollable because I see 33 million inserts in cfstats and the size of the stables
is over 10 gigs all in an hour of uptime. 
> 
> 
> I have done the following to try and reproduce this:
> 
> - shut down my cluster
> - on all nodes: remove sstables from the HintsColumnFamily data dir
> - on all nodes: remove commit logs
> - start all nodes but the one that’s showing this problem
> - nothing is writing to any of the nodes. There are no hinted handoff going on anywhere
> - bring back the node in question last
> - few seconds after boot:
> 
>                 Column Family: HintsColumnFamily
>                 SSTable count: 1
>                 Space used (live): 44946532
>                 Space used (total): 44946532
>                 Number of Keys (estimate): 256
>                 Memtable Columns Count: 17840
>                 Memtable Data Size: 17569909
>                 Memtable Switch Count: 2
>                 Read Count: 0
>                 Read Latency: NaN ms.
>                 Write Count: 184836
>                 Write Latency: 0.668 ms.
>                 Pending Tasks: 0
>                 Bloom Filter False Postives: 0
>                 Bloom Filter False Ratio: 0.00000
>                 Bloom Filter Space Used: 16
>                 Compacted row minimum size: 20924301
>                 Compacted row maximum size: 25109160
>                 Compacted row mean size: 25109160
> 
> 
> 
> 


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