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From Bryan Keller <brya...@gmail.com>
Subject Re: xceiver count, regionserver shutdown
Date Mon, 06 Feb 2012 21:12:41 GMT
This is happening during heavy update. I have a "wide" table with around 4 million rows that
have already been inserted. I am adding billions of columns to the rows. Each row can have
20+k columns.

I perform the updates in batch, i.e. I am using the HTable.put(List<Put>) API. The batch
size is 1000 Puts. The columns being added are scattered, e.g. I may add 20 columns to 1000
different rows in each batch. Then in the next batch add 20 columns to 1000 more rows (which
may be the same rows or different than the previous batch), and so forth.

BTW, I tried upping the "xcievers" parameter to 8192 but now I'm getting a "Too many open
files" error. I have the file limit set to 32k.


On Feb 6, 2012, at 11:59 AM, Jean-Daniel Cryans wrote:

> The number of regions is the first thing to check, then it's about the
> actual number of blocks opened. Is the issue happening during a heavy
> insert? In this case I guess you could end up with hundreds of opened
> files if the compactions are piling up. Setting a bigger memstore
> flush size would definitely help... but then again if your insert
> pattern is random enough all 200 regions will have filled memstores so
> you'd end up with hundreds of super small files...
> 
> Please tell us more about the context of when this issue happens.
> 
> J-D
> 
> On Mon, Feb 6, 2012 at 11:42 AM, Bryan Keller <bryanck@gmail.com> wrote:
>> I am trying to resolve an issue with my cluster when I am loading a bunch of data
into HBase. I am reaching the "xciever" limit on the data nodes. Currently I have this set
to 4096. The data node is logging "xceiverCount 4097 exceeds the limit of concurrent xcievers
4096". The regionservers eventually shut down. I have read the various threads on this issue.
>> 
>> I have 4 datanodes/regionservers. Each regionserver has only around 200 regions.
The table has 2 column families. I have the region file size set to 500mb, and I'm using Snappy
compression. This problem is occurring on HBase 0.90.4 and Hadoop 0.20.2 (both Cloudera cdh3u3).
>> 
>> From what I have read, the number of regions on a node can cause the xceiver limit
to be reached, but it doesn't seem like I have an excessive number of regions. I want the
table to scale higher, so simply upping the xceiver limit could perhaps get my table functional
for now, but it seems it will only be a temporary fix.
>> 
>> Are number of regions the only factor that can cause this problem, or are there other
factors involved that I may be able to adjust?
>> 


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