hbase-issues mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From "Derek Wollenstein (JIRA)" <j...@apache.org>
Subject [jira] [Created] (HBASE-5920) New Compactions Logic can silently prevent user-initiated compactions from occurring
Date Wed, 02 May 2012 20:14:49 GMT
Derek Wollenstein created HBASE-5920:
----------------------------------------

             Summary: New Compactions Logic can silently prevent user-initiated compactions
from occurring
                 Key: HBASE-5920
                 URL: https://issues.apache.org/jira/browse/HBASE-5920
             Project: HBase
          Issue Type: Bug
          Components: client, regionserver
    Affects Versions: 0.92.1
            Reporter: Derek Wollenstein
            Priority: Minor


There seem to be some tuning settings in which manually triggered major compactions will do
nothing, including loggic

>From Store.java in the function
  List<StoreFile> compactSelection(List<StoreFile> candidates)

When a user manually triggers a compaction, this follows the same logic as a normal compaction
check.  when a user manually triggers a major compaction, something similar happens.  Putting
this all together:

1. If a user triggers a major compaction, this is checked against a max files threshold (hbase.hstore.compaction.max).
If the number of storefiles to compact is > max files, then we downgrade to a minor compaction
2. If we are in a minor compaction, we do the following checks:
   a. If the file is less than a minimum size (hbase.hstore.compaction.min.size) we automatically
include it
   b. Otherwise, we check how the size compares to the next largest size.  based on hbase.hstore.compaction.ratio.
 
  c. If the number of files included is less than a minimum count (hbase.hstore.compaction.min)
then don't compact.
In many of the exit strategies, we aren't seeing an error message.
The net-net of this is that if we have a mix of very large and very small files, we may end
up having too many files to do a major compact, but too few files to do a minor compact.

I'm trying to go through and see if I'm understanding things correctly, but this seems like
the bug

To put it another way
2012-05-02 20:09:36,389 DEBUG org.apache.hadoop.hbase.regionserver.CompactSplitThread: Large
Compaction requested: regionName=str,44594594594594592,1334939064521.f7aed25b55d4d7988af763bede9ce74e.,
store
Name=c, fileCount=15, fileSize=1.5g (20.2k, 362.5m, 155.3k, 3.0m, 30.7k, 361.2m, 6.9m, 4.7m,
14.7k, 363.4m, 30.9m, 3.2m, 7.3k, 362.9m, 23.5m), priority=-9, time=3175046817624398; Because:
Recursive enqueue; compaction_queue=(59:0), split_queue=0

When we had a minimum compaction size of 128M, and default settings for hbase.hstore.compaction.min,hbase.hstore.compaction.max,hbase.hstore.compaction.ratio,
we were not getting a compaction to run even if we ran
major_compact 'str,44594594594594592,1334939064521.f7aed25b55d4d7988af763bede9ce74e.' from
the ruby shell.  Note that we had many tiny regions (20k, 155k, 3m, 30k,..) and several large
regions (362.5m,361.2m,363.4m,362.9m).  I think the bimodal nature of the sizes prevented
us from doing a compaction.
I'm not 100% sure where this errored out because when I manually triggered a compaction, I
did not see
'      // if we don't have enough files to compact, just wait             
      if (filesToCompact.size() < this.minFilesToCompact) {              
        if (LOG.isDebugEnabled()) {                                      
          LOG.debug("Skipped compaction of " + this.storeNameStr         
            + ".  Only " + (end - start) + " file(s) of size "           
            + StringUtils.humanReadableInt(totalSize)                    
            + " have met compaction criteria.");                         
        }                                                                
' 
being printed in the logs (and I know DEBUG logging was enabled because I saw this elsewhere).
 

I'd be happy with better error messages when we decide not to compact for user enabled compactions.
I'd also like to see some override that says "user triggered major compaction always occurs",
but maybe that's a bad idea for other reasons.


--
This message is automatically generated by JIRA.
If you think it was sent incorrectly, please contact your JIRA administrators: https://issues.apache.org/jira/secure/ContactAdministrators!default.jspa
For more information on JIRA, see: http://www.atlassian.com/software/jira

        

Mime
View raw message