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From Ted Yu <yuzhih...@gmail.com>
Subject Re: Balancer switch runs causing problems
Date Tue, 28 Jan 2014 04:23:38 GMT
Looking at the changes since release 0.94.7, I found:

HBASE-8655 Backport to 94 - HBASE-8346(Prefetching .META. rows in case only
when useCache is set to true)
HBASE-8698 potential thread creation in MetaScanner.metaScan

If possible, can you upgrade your cluster ?

Cheers


On Mon, Jan 27, 2014 at 8:02 PM, Ted Yu <yuzhihong@gmail.com> wrote:

> Do you see the following (from
> HConnectionManager$HConnectionImplementation#locateRegionInMeta) ?
>
>             if (LOG.isDebugEnabled()) {
>               LOG.debug("locateRegionInMeta parentTable=" +
>                 Bytes.toString(parentTable) + ", metaLocation=" +
>                 ((metaLocation == null)? "null": "{" + metaLocation + "}")
> +
>                 ", attempt=" + tries + " of " +
>                 this.numRetries + " failed; retrying after sleep of " +
>
>
> On Mon, Jan 27, 2014 at 7:51 PM, Varun Sharma <varun@pinterest.com> wrote:
>
>> Actually not sometimes but we are always seeing a large # of .META. reads
>> every 5 minutes.
>>
>>
>> On Mon, Jan 27, 2014 at 7:47 PM, Varun Sharma <varun@pinterest.com>
>> wrote:
>>
>> > The default one with 0.94.7... - I dont see any of those logs. Also we
>> > turned off the balancer switch - but looks like sometimes we still see a
>> > large number of requests to .META. table every 5 minutes.
>> >
>> > Varun
>> >
>> >
>> > On Mon, Jan 27, 2014 at 7:37 PM, Ted Yu <yuzhihong@gmail.com> wrote:
>> >
>> >> In HMaster#balance(), we have (same for 0.94 and 0.96):
>> >>
>> >>         for (RegionPlan plan: plans) {
>> >>           LOG.info("balance " + plan);
>> >>
>> >> Do you see such log in master log ?
>> >>
>> >>
>> >> On Mon, Jan 27, 2014 at 7:26 PM, Varun Sharma <varun@pinterest.com>
>> >> wrote:
>> >>
>> >> > We are seeing one other issue with high read latency (p99 etc.) on
>> one
>> >> of
>> >> > our read heavy hbase clusters which is correlated with the balancer
>> >> runs -
>> >> > every 5 minutes.
>> >> >
>> >> > If there is no balancing to do, does the balancer only scan the table
>> >> every
>> >> > 5 minutes - does it do anything on top of that if the regions are
>> >> balanced
>> >> > ?
>> >> >
>> >> > Varun
>> >> >
>> >>
>> >
>> >
>>
>
>

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