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From "Billy Pearson (JIRA)" <j...@apache.org>
Subject [jira] Commented: (HADOOP-2587) Splits getting blocked by compactions causeing region to be offline for the length of the compaction 10-15 mins
Date Mon, 14 Jan 2008 06:35:34 GMT

    [ https://issues.apache.org/jira/browse/HADOOP-2587?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12558516#action_12558516
] 

Billy Pearson commented on HADOOP-2587:
---------------------------------------

take my last post back looks like its working at 100%

{code}
2008-01-14 00:09:18,635 DEBUG org.apache.hadoop.hbase.HRegion: compactions and cache flushes
disabled for region webdata,,1200287612662
{code}

I did not see this my logs stop tail as midnight passed but reviewing the logs and see the
table had split 6 times and I thought I was still waiting on the first split to happen.

thanks for the patch


> Splits getting blocked by compactions causeing region to be offline for the length of
the compaction 10-15 mins
> ---------------------------------------------------------------------------------------------------------------
>
>                 Key: HADOOP-2587
>                 URL: https://issues.apache.org/jira/browse/HADOOP-2587
>             Project: Hadoop
>          Issue Type: Bug
>          Components: contrib/hbase
>    Affects Versions: 0.16.0
>         Environment: hadoop subversion 611087
>            Reporter: Billy Pearson
>            Assignee: Jim Kellerman
>             Fix For: 0.16.0
>
>         Attachments: hbase-root-regionserver-PE1750-3.log, log.log, patch.txt, patch.txt
>
>
> The below is cut out of one of my region servers logs full log attached
> What is happening is there is one region on a this region server and its is under heave
insert load so compaction are back to back one one finishes a new one starts the problem starts
when its time to split the region. 
> A compaction starts just millsecs before the split starts blocking the split but the
split closes the region before the compaction is finished. Causing the region to be offline
until the compaction is done. Once the compaction is done the split finishes and all is returned
to normal but this is a big problem for production if the region is offline for 10-15 mins.
> The solution would be not to let the split thread to issue the below line while a compaction
on that region is happening.
> 2008-01-11 16:22:01,247 DEBUG org.apache.hadoop.hbase.HRegionServer: webdata,,1200085987488
closing (Adding to retiringRegions)
> The only time I have seen this bug is when there is only one region on a region server
because if more then one then the compaction happens to the other region(s) after the first
one is done compaction and the split can do what it needs on the first region with out getting
blocked.
> {code}
> 2008-01-11 16:22:01,020 INFO org.apache.hadoop.hbase.HRegion: compaction completed on
region webdata,,1200085987488. Took 16mins, 10sec
> 2008-01-11 16:22:01,020 DEBUG org.apache.hadoop.hbase.HStore: compaction for HStore webdata,,1200085987488/size
needed.
> 2008-01-11 16:22:01,020 DEBUG org.apache.hadoop.hbase.HRegion: 1773667150/size needs
compaction
> 2008-01-11 16:22:01,021 INFO org.apache.hadoop.hbase.HRegion: starting compaction on
region webdata,,1200085987488
> 2008-01-11 16:22:01,021 DEBUG org.apache.hadoop.hbase.HStore: started compaction of 14
files using /gfs_storage/hadoop-root/hbase/hregion_1773667150/compaction.dir/hregion_1773667150/size
for webdata,,1200085987488/size
> 2008-01-11 16:22:01,123 DEBUG org.apache.hadoop.hbase.HRegion: Started memcache flush
for region webdata,,1200085987488. Size 31.2m
> 2008-01-11 16:22:01,232 INFO org.apache.hadoop.hbase.HRegion: Splitting webdata,,1200085987488
because largest aggregate size is 100.7m and desired size is 64.0m
> 2008-01-11 16:22:01,247 DEBUG org.apache.hadoop.hbase.HRegionServer: webdata,,1200085987488
closing (Adding to retiringRegions)
> ...
> lots of NotServingRegionException's
> ...
> 2008-01-11 16:32:59,876 INFO org.apache.hadoop.hbase.HRegion: compaction completed on
region webdata,,1200085987488. Took 10mins, 58sec
> ...
> 2008-01-11 16:33:02,193 DEBUG org.apache.hadoop.hbase.HRegion: Cleaned up /gfs_storage/hadoop-root/hbase/hregion_1773667150/splits
true
> 2008-01-11 16:33:02,194 INFO org.apache.hadoop.hbase.HRegion: Region split of webdata,,1200085987488
complete; new regions: webdata,,1200090121237, webdata,com.tom.ent/2008-01-04/0PGM/09034104.html:http,1200090121239.
Split took 11mins, 0sec
> 2008-01-11 16:33:02,227 DEBUG org.apache.hadoop.hbase.HConnectionManager$TableServers:
No servers for .META.. Doing a find...
> 2008-01-11 16:33:02,283 DEBUG org.apache.hadoop.hbase.HConnectionManager$TableServers:
Found 1 region(s) for .META. at address: 10.0.0.4:60020, regioninfo: regionname: -ROOT-,,0,
startKey: <>, encodedName(70236052) tableDesc: {name: -ROOT-, families: {info:={name:
info, max versions: 1, compression: NONE, in memory: false, max length: 2147483647, bloom
filter: none}}}
> 2008-01-11 16:33:02,284 INFO org.apache.hadoop.hbase.HRegionServer: Updating .META. with
region split info
> 2008-01-11 16:33:02,290 DEBUG org.apache.hadoop.hbase.HRegionServer: Reporting region
split to master
> 2008-01-11 16:33:02,291 INFO org.apache.hadoop.hbase.HRegionServer: region split, META
update, and report to master all successful. Old region=webdata,,1200085987488, new regions:
webdata,,1200090121237, webdata,com.tom.ent/2008-01-04/0PGM/09034104.html:http,1200090121239
> {code}

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