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HBase >> mail # user >> M/R scan problem


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Lior Schachter 2011-07-04, 11:48
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Ted Yu 2011-07-04, 14:22
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Lior Schachter 2011-07-04, 14:37
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Ted Yu 2011-07-04, 14:55
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Lior Schachter 2011-07-04, 15:15
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Ted Yu 2011-07-04, 15:22
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Lior Schachter 2011-07-04, 16:26
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Ted Yu 2011-07-04, 16:33
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Lior Schachter 2011-07-04, 16:47
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Ted Yu 2011-07-04, 17:12
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Ted Yu 2011-07-04, 17:13
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Re: M/R scan problem
I will increase the number of connections to 1000.

Thanks !

Lior
On Mon, Jul 4, 2011 at 8:12 PM, Ted Yu <[EMAIL PROTECTED]> wrote:

> The reason I asked about HBaseURLsDaysAggregator.java was that I see no
> HBase (client) code in call stack.
> I have little clue for the problem you experienced.
>
> There may be more than one connection to zookeeper from one map task.
> So it doesn't hurt if you increase hbase.zookeeper.property.maxClientCnxns
>
> Cheers
>
> On Mon, Jul 4, 2011 at 9:47 AM, Lior Schachter <[EMAIL PROTECTED]>
> wrote:
>
> > 1. HBaseURLsDaysAggregator.java:124, HBaseURLsDaysAggregator.java:131 :
> are
> > not important since even when I removed all my map code the tasks got
> stuck
> > (but the thread dumps were generated after I revived the code). If you
> > think
> > its important I'll remove the map code again and re-generate the thread
> > dumps...
> >
> > 2. 82 maps were launched but only 36 ran simultaneously.
> >
> > 3. hbase.zookeeper.property.maxClientCnxns = 300. Should I increase it ?
> >
> > Thanks,
> > Lior
> >
> >
> > On Mon, Jul 4, 2011 at 7:33 PM, Ted Yu <[EMAIL PROTECTED]> wrote:
> >
> > > In the future, provide full dump using pastebin.com
> > > Write snippet of log in email.
> > >
> > > Can you tell us what the following lines are about ?
> > > HBaseURLsDaysAggregator.java:124
> > > HBaseURLsDaysAggregator.java:131
> > >
> > > How many mappers were launched ?
> > >
> > > What value is used for hbase.zookeeper.property.maxClientCnxns ?
> > > You may need to increase the value for above setting.
> > >
> > > On Mon, Jul 4, 2011 at 9:26 AM, Lior Schachter <[EMAIL PROTECTED]>
> > > wrote:
> > >
> > > > I used kill -3, following the thread dump:
> > > >
> > > > ...
> > > >
> > > >
> > > > On Mon, Jul 4, 2011 at 6:22 PM, Ted Yu <[EMAIL PROTECTED]> wrote:
> > > >
> > > > > I wasn't clear in my previous email.
> > > > > It was not answer to why map tasks got stuck.
> > > > > TableInputFormatBase.getSplits() is being called already.
> > > > >
> > > > > Can you try getting jstack of one of the map tasks before task
> > tracker
> > > > > kills
> > > > > it ?
> > > > >
> > > > > Thanks
> > > > >
> > > > > On Mon, Jul 4, 2011 at 8:15 AM, Lior Schachter <
> [EMAIL PROTECTED]>
> > > > > wrote:
> > > > >
> > > > > > 1. Currently every map gets one region. So I don't understand
> what
> > > > > > difference will it make using the splits.
> > > > > > 2. How should I use the TableInputFormatBase.getSplits() ? Could
> > not
> > > > find
> > > > > > examples for that.
> > > > > >
> > > > > > Thanks,
> > > > > > Lior
> > > > > >
> > > > > >
> > > > > > On Mon, Jul 4, 2011 at 5:55 PM, Ted Yu <[EMAIL PROTECTED]>
> > wrote:
> > > > > >
> > > > > > > For #2, see TableInputFormatBase.getSplits():
> > > > > > >   * Calculates the splits that will serve as input for the map
> > > tasks.
> > > > > The
> > > > > > >   * number of splits matches the number of regions in a table.
> > > > > > >
> > > > > > >
> > > > > > > On Mon, Jul 4, 2011 at 7:37 AM, Lior Schachter <
> > > [EMAIL PROTECTED]>
> > > > > > > wrote:
> > > > > > >
> > > > > > > > 1. yes - I configure my job using this line:
> > > > > > > >
> > > TableMapReduceUtil.initTableMapperJob(HBaseConsts.URLS_TABLE_NAME,
> > > > > > scan,
> > > > > > > > ScanMapper.class, Text.class, MapWritable.class, job)
> > > > > > > >
> > > > > > > > which internally uses TableInputFormat.class
> > > > > > > >
> > > > > > > > 2. One split per region ? What do you mean ? How do I do that
> ?
> > > > > > > >
> > > > > > > > 3. hbase version 0.90.2
> > > > > > > >
> > > > > > > > 4. no exceptions. the logs are very clean.
> > > > > > > >
> > > > > > > >
> > > > > > > >
> > > > > > > > On Mon, Jul 4, 2011 at 5:22 PM, Ted Yu <[EMAIL PROTECTED]>
> > > > wrote:
> > > > > > > >
> > > > > > > > > Do you use TableInputFormat ?
> > > > > > > > > To scan large number of rows, it would be better to produce
> > one
> > > > > Split
> > > > > > > per
> > > > > > > > > region.
> > > > > > > > >
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Ted Yu 2011-07-04, 17:35
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Michel Segel 2011-07-04, 19:36