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Posted to issues@hbase.apache.org by "binlijin (Created) (JIRA)" <ji...@apache.org> on 2012/04/02 20:19:23 UTC

[jira] [Created] (HBASE-5699) Should we use muti HLog or Writer in HLog in a HRegionServer

Should we use muti HLog or Writer in HLog in a HRegionServer
------------------------------------------------------------

                 Key: HBASE-5699
                 URL: https://issues.apache.org/jira/browse/HBASE-5699
             Project: HBase
          Issue Type: Improvement
            Reporter: binlijin




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[jira] [Commented] (HBASE-5699) Run with > 1 WAL in HRegionServer

Posted by "Zhihong Yu (JIRA)" <ji...@apache.org>.
    [ https://issues.apache.org/jira/browse/HBASE-5699?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13268093#comment-13268093 ] 

Zhihong Yu commented on HBASE-5699:
-----------------------------------

Here're the key unit tests that must pass:

TestDistributedLogSplitting, TestReplication, TestMasterReplication, TestMultiSlaveReplication, TestHLog, TestHLogSplit, TestLogRollAbort, TestLogRolling
                
> Run with > 1 WAL in HRegionServer
> ---------------------------------
>
>                 Key: HBASE-5699
>                 URL: https://issues.apache.org/jira/browse/HBASE-5699
>             Project: HBase
>          Issue Type: Improvement
>            Reporter: binlijin
>            Assignee: Li Pi
>


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[jira] [Commented] (HBASE-5699) Run with > 1 WAL in HRegionServer

Posted by "stack (JIRA)" <ji...@apache.org>.
    [ https://issues.apache.org/jira/browse/HBASE-5699?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13289161#comment-13289161 ] 

stack commented on HBASE-5699:
------------------------------

Whats the high level on the perf numbers?  Does more WALs help?  How much?  Thanks.
                
> Run with > 1 WAL in HRegionServer
> ---------------------------------
>
>                 Key: HBASE-5699
>                 URL: https://issues.apache.org/jira/browse/HBASE-5699
>             Project: HBase
>          Issue Type: Improvement
>            Reporter: binlijin
>            Assignee: Li Pi
>         Attachments: PerfHbase.txt
>
>


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[jira] [Commented] (HBASE-5699) Run with > 1 WAL in HRegionServer

Posted by "Lars Hofhansl (JIRA)" <ji...@apache.org>.
    [ https://issues.apache.org/jira/browse/HBASE-5699?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13279078#comment-13279078 ] 

Lars Hofhansl commented on HBASE-5699:
--------------------------------------

Should we explore a WAL per Region? Would be a lot of open files, but if it'd work, we won't need log spitting anymore.
                
> Run with > 1 WAL in HRegionServer
> ---------------------------------
>
>                 Key: HBASE-5699
>                 URL: https://issues.apache.org/jira/browse/HBASE-5699
>             Project: HBase
>          Issue Type: Improvement
>            Reporter: binlijin
>            Assignee: Li Pi
>


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[jira] [Commented] (HBASE-5699) Run with > 1 WAL in HRegionServer

Posted by "Todd Lipcon (JIRA)" <ji...@apache.org>.
    [ https://issues.apache.org/jira/browse/HBASE-5699?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13265421#comment-13265421 ] 

Todd Lipcon commented on HBASE-5699:
------------------------------------

bq. I disagree, considering that most of the deployments have rep=3 you're using three spindles not one

That said, most of our customers are deploying 6 disks if not 12 :)

IMO the other big gain we can get from multiple WALs is to automatically switch between WALs when one gets "slow". IMO we should maintain a count of outstanding requests (probably by size) for each WAL, and submit writes to whichever has fewer outstanding requests. That way if one is faster, it will take more of the load. Then simultaneously measure trailing latency stats on each WAL, and if one is significantly slower than the other for some period of time, have it roll (to try to get a new set of disks/nodes)
                
> Run with > 1 WAL in HRegionServer
> ---------------------------------
>
>                 Key: HBASE-5699
>                 URL: https://issues.apache.org/jira/browse/HBASE-5699
>             Project: HBase
>          Issue Type: Improvement
>            Reporter: binlijin
>            Assignee: Li Pi
>


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[jira] [Commented] (HBASE-5699) Run with > 1 WAL in HRegionServer

Posted by "Jonathan Hsieh (JIRA)" <ji...@apache.org>.
    [ https://issues.apache.org/jira/browse/HBASE-5699?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13265567#comment-13265567 ] 

Jonathan Hsieh commented on HBASE-5699:
---------------------------------------

The argument here is mostly aimed at read latency, but a similar idea could be used for write latency as well.
                
> Run with > 1 WAL in HRegionServer
> ---------------------------------
>
>                 Key: HBASE-5699
>                 URL: https://issues.apache.org/jira/browse/HBASE-5699
>             Project: HBase
>          Issue Type: Improvement
>            Reporter: binlijin
>            Assignee: Li Pi
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[jira] [Commented] (HBASE-5699) Run with > 1 WAL in HRegionServer

Posted by "Jonathan Hsieh (JIRA)" <ji...@apache.org>.
    [ https://issues.apache.org/jira/browse/HBASE-5699?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13268196#comment-13268196 ] 

Jonathan Hsieh commented on HBASE-5699:
---------------------------------------

Li, if you want to undertake this I'll help.  Let's chat and then write a one-two page summary of what our goals are, what our assumptions are, and what our intended mechanisms are, how we are going to test this and then loopback here with a design/plan to get feedback..  

Another "feature" that may come into play also is the HLog compression.
                
> Run with > 1 WAL in HRegionServer
> ---------------------------------
>
>                 Key: HBASE-5699
>                 URL: https://issues.apache.org/jira/browse/HBASE-5699
>             Project: HBase
>          Issue Type: Improvement
>            Reporter: binlijin
>            Assignee: Li Pi
>


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[jira] [Commented] (HBASE-5699) Run with > 1 WAL in HRegionServer

Posted by "ramkrishna.s.vasudevan (JIRA)" <ji...@apache.org>.
    [ https://issues.apache.org/jira/browse/HBASE-5699?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13265648#comment-13265648 ] 

ramkrishna.s.vasudevan commented on HBASE-5699:
-----------------------------------------------

Do we need to gurantee the HLog edits sequencing even with multiple WALs? Just referring to Stack's comment in 
https://issues.apache.org/jira/browse/HBASE-5782?focusedCommentId=13255344&page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#comment-13255344
                
> Run with > 1 WAL in HRegionServer
> ---------------------------------
>
>                 Key: HBASE-5699
>                 URL: https://issues.apache.org/jira/browse/HBASE-5699
>             Project: HBase
>          Issue Type: Improvement
>            Reporter: binlijin
>            Assignee: Li Pi
>


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[jira] [Commented] (HBASE-5699) Run with > 1 WAL in HRegionServer

Posted by "Li Pi (Commented) (JIRA)" <ji...@apache.org>.
    [ https://issues.apache.org/jira/browse/HBASE-5699?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13250470#comment-13250470 ] 

Li Pi commented on HBASE-5699:
------------------------------

This seems interesting. I'll take a look at doing this.
                
> Run with > 1 WAL in HRegionServer
> ---------------------------------
>
>                 Key: HBASE-5699
>                 URL: https://issues.apache.org/jira/browse/HBASE-5699
>             Project: HBase
>          Issue Type: Improvement
>            Reporter: binlijin
>


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[jira] [Commented] (HBASE-5699) Run with > 1 WAL in HRegionServer

Posted by "Juhani Connolly (Commented) (JIRA)" <ji...@apache.org>.
    [ https://issues.apache.org/jira/browse/HBASE-5699?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13246971#comment-13246971 ] 

Juhani Connolly commented on HBASE-5699:
----------------------------------------

Since we have had some similar experience posting it here:
We are finding most of our IPC threads in our region servers locked into HWal.append(42 out of 50. Of those 20 are in sync, and one is actually working... As is to be expected).
We made the presumption that the problem was with the WAL synchronisation mechanisms holding things up and decided to try running multiple RS per node since we had significant amount of free CPU and memory resources as well as many barely active hard disks.
By running 3 RS per node, we saw our application specific throughput go from 7k events to 18k. Each event is made up of roughly 2 writes and 2 increments, plus some reads/scans which shouldn't be touching the WAL.
This situation is partially also just due to a very high spec per node. I don't think it would be necessary on more "commodity" type servers, but the option to use multiple WAL's on each region server may well give some significant throughput gains for some hardware setups.
                
> Run with > 1 WAL in HRegionServer
> ---------------------------------
>
>                 Key: HBASE-5699
>                 URL: https://issues.apache.org/jira/browse/HBASE-5699
>             Project: HBase
>          Issue Type: Improvement
>            Reporter: binlijin
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[jira] [Commented] (HBASE-5699) Run with > 1 WAL in HRegionServer

Posted by "Li Pi (JIRA)" <ji...@apache.org>.
    [ https://issues.apache.org/jira/browse/HBASE-5699?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13265426#comment-13265426 ] 

Li Pi commented on HBASE-5699:
------------------------------

Agree with todd on the implementation details. The switching of logs should also serve to help balance our log writes. 
                
> Run with > 1 WAL in HRegionServer
> ---------------------------------
>
>                 Key: HBASE-5699
>                 URL: https://issues.apache.org/jira/browse/HBASE-5699
>             Project: HBase
>          Issue Type: Improvement
>            Reporter: binlijin
>            Assignee: Li Pi
>


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[jira] [Commented] (HBASE-5699) Run with > 1 WAL in HRegionServer

Posted by "Li Pi (JIRA)" <ji...@apache.org>.
    [ https://issues.apache.org/jira/browse/HBASE-5699?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13279327#comment-13279327 ] 

Li Pi commented on HBASE-5699:
------------------------------

Btw. I have finals and other stuff coming up. So it might be a while before
I finish my implementation. If anyone else wants to take a go at it. This
is cool.


                
> Run with > 1 WAL in HRegionServer
> ---------------------------------
>
>                 Key: HBASE-5699
>                 URL: https://issues.apache.org/jira/browse/HBASE-5699
>             Project: HBase
>          Issue Type: Improvement
>            Reporter: binlijin
>            Assignee: Li Pi
>


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[jira] [Commented] (HBASE-5699) Run with > 1 WAL in HRegionServer

Posted by "Zhihong Yu (JIRA)" <ji...@apache.org>.
    [ https://issues.apache.org/jira/browse/HBASE-5699?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13279125#comment-13279125 ] 

Zhihong Yu commented on HBASE-5699:
-----------------------------------

There would be many regions in a cluster. They may not receive even write load.

We should set configuration parameter which governs the maximum number of concurrent WALs on each region server.
                
> Run with > 1 WAL in HRegionServer
> ---------------------------------
>
>                 Key: HBASE-5699
>                 URL: https://issues.apache.org/jira/browse/HBASE-5699
>             Project: HBase
>          Issue Type: Improvement
>            Reporter: binlijin
>            Assignee: Li Pi
>


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[jira] [Commented] (HBASE-5699) Run with > 1 WAL in HRegionServer

Posted by "Li Pi (JIRA)" <ji...@apache.org>.
    [ https://issues.apache.org/jira/browse/HBASE-5699?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13268010#comment-13268010 ] 

Li Pi commented on HBASE-5699:
------------------------------

I'm assuming we don't need to guarantee HLog edit sequencing. If we do, this becomes a bit harder.
                
> Run with > 1 WAL in HRegionServer
> ---------------------------------
>
>                 Key: HBASE-5699
>                 URL: https://issues.apache.org/jira/browse/HBASE-5699
>             Project: HBase
>          Issue Type: Improvement
>            Reporter: binlijin
>            Assignee: Li Pi
>


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[jira] [Commented] (HBASE-5699) Run with > 1 WAL in HRegionServer

Posted by "Zhihong Yu (JIRA)" <ji...@apache.org>.
    [ https://issues.apache.org/jira/browse/HBASE-5699?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13265620#comment-13265620 ] 

Zhihong Yu commented on HBASE-5699:
-----------------------------------

Currently we maintain one sequence number per region per HLog. From append():
{code}
      this.lastSeqWritten.putIfAbsent(regionInfo.getEncodedNameAsBytes(),
        Long.valueOf(seqNum));
{code}
If WALEdit's from a particular region can spread across multiple streams, accounting would be more complex.
                
> Run with > 1 WAL in HRegionServer
> ---------------------------------
>
>                 Key: HBASE-5699
>                 URL: https://issues.apache.org/jira/browse/HBASE-5699
>             Project: HBase
>          Issue Type: Improvement
>            Reporter: binlijin
>            Assignee: Li Pi
>


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[jira] [Commented] (HBASE-5699) Run with > 1 WAL in HRegionServer

Posted by "Hudson (JIRA)" <ji...@apache.org>.
    [ https://issues.apache.org/jira/browse/HBASE-5699?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13468087#comment-13468087 ] 

Hudson commented on HBASE-5699:
-------------------------------

Integrated in HBase-TRUNK #3408 (See [https://builds.apache.org/job/HBase-TRUNK/3408/])
    HBASE-5699 Refactor HLog into an interface (Revision 1393126)

     Result = FAILURE
stack : 
Files : 
* /hbase/trunk/hbase-server/src/main/java/org/apache/hadoop/hbase/backup/example/LongTermArchivingHFileCleaner.java
* /hbase/trunk/hbase-server/src/main/java/org/apache/hadoop/hbase/fs/HFileSystem.java
* /hbase/trunk/hbase-server/src/main/java/org/apache/hadoop/hbase/mapreduce/HLogInputFormat.java
* /hbase/trunk/hbase-server/src/main/java/org/apache/hadoop/hbase/mapreduce/WALPlayer.java
* /hbase/trunk/hbase-server/src/main/java/org/apache/hadoop/hbase/master/MasterFileSystem.java
* /hbase/trunk/hbase-server/src/main/java/org/apache/hadoop/hbase/master/cleaner/CleanerChore.java
* /hbase/trunk/hbase-server/src/main/java/org/apache/hadoop/hbase/master/cleaner/HFileCleaner.java
* /hbase/trunk/hbase-server/src/main/java/org/apache/hadoop/hbase/master/cleaner/LogCleaner.java
* /hbase/trunk/hbase-server/src/main/java/org/apache/hadoop/hbase/protobuf/ProtobufUtil.java
* /hbase/trunk/hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/HRegion.java
* /hbase/trunk/hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/HRegionServer.java
* /hbase/trunk/hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/metrics/RegionServerMetrics.java
* /hbase/trunk/hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/wal/Compressor.java
* /hbase/trunk/hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/wal/FSHLog.java
* /hbase/trunk/hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/wal/HLog.java
* /hbase/trunk/hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/wal/HLogFactory.java
* /hbase/trunk/hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/wal/HLogMetrics.java
* /hbase/trunk/hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/wal/HLogPrettyPrinter.java
* /hbase/trunk/hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/wal/HLogSplitter.java
* /hbase/trunk/hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/wal/HLogUtil.java
* /hbase/trunk/hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/wal/SequenceFileLogReader.java
* /hbase/trunk/hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/wal/SequenceFileLogWriter.java
* /hbase/trunk/hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/wal/WALActionsListener.java
* /hbase/trunk/hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/wal/WALCoprocessorHost.java
* /hbase/trunk/hbase-server/src/main/java/org/apache/hadoop/hbase/replication/regionserver/ReplicationSource.java
* /hbase/trunk/hbase-server/src/main/java/org/apache/hadoop/hbase/util/HBaseFsck.java
* /hbase/trunk/hbase-server/src/main/java/org/apache/hadoop/hbase/util/HFileArchiveUtil.java
* /hbase/trunk/hbase-server/src/main/java/org/apache/hadoop/hbase/util/HMerge.java
* /hbase/trunk/hbase-server/src/main/java/org/apache/hadoop/hbase/util/MetaUtils.java
* /hbase/trunk/hbase-server/src/test/java/org/apache/hadoop/hbase/backup/example/TestZooKeeperTableArchiveClient.java
* /hbase/trunk/hbase-server/src/test/java/org/apache/hadoop/hbase/coprocessor/TestRowProcessorEndpoint.java
* /hbase/trunk/hbase-server/src/test/java/org/apache/hadoop/hbase/coprocessor/TestWALObserver.java
* /hbase/trunk/hbase-server/src/test/java/org/apache/hadoop/hbase/fs/TestBlockReorder.java
* /hbase/trunk/hbase-server/src/test/java/org/apache/hadoop/hbase/mapreduce/TestHLogRecordReader.java
* /hbase/trunk/hbase-server/src/test/java/org/apache/hadoop/hbase/master/TestDistributedLogSplitting.java
* /hbase/trunk/hbase-server/src/test/java/org/apache/hadoop/hbase/regionserver/TestCacheOnWriteInSchema.java
* /hbase/trunk/hbase-server/src/test/java/org/apache/hadoop/hbase/regionserver/TestCompactSelection.java
* /hbase/trunk/hbase-server/src/test/java/org/apache/hadoop/hbase/regionserver/TestHRegion.java
* /hbase/trunk/hbase-server/src/test/java/org/apache/hadoop/hbase/regionserver/TestSplitTransaction.java
* /hbase/trunk/hbase-server/src/test/java/org/apache/hadoop/hbase/regionserver/TestStore.java
* /hbase/trunk/hbase-server/src/test/java/org/apache/hadoop/hbase/regionserver/wal/FaultySequenceFileLogReader.java
* /hbase/trunk/hbase-server/src/test/java/org/apache/hadoop/hbase/regionserver/wal/HLogPerformanceEvaluation.java
* /hbase/trunk/hbase-server/src/test/java/org/apache/hadoop/hbase/regionserver/wal/HLogUtilsForTests.java
* /hbase/trunk/hbase-server/src/test/java/org/apache/hadoop/hbase/regionserver/wal/TestHLog.java
* /hbase/trunk/hbase-server/src/test/java/org/apache/hadoop/hbase/regionserver/wal/TestHLogMethods.java
* /hbase/trunk/hbase-server/src/test/java/org/apache/hadoop/hbase/regionserver/wal/TestHLogSplit.java
* /hbase/trunk/hbase-server/src/test/java/org/apache/hadoop/hbase/regionserver/wal/TestLogRollAbort.java
* /hbase/trunk/hbase-server/src/test/java/org/apache/hadoop/hbase/regionserver/wal/TestLogRolling.java
* /hbase/trunk/hbase-server/src/test/java/org/apache/hadoop/hbase/regionserver/wal/TestLogRollingNoCluster.java
* /hbase/trunk/hbase-server/src/test/java/org/apache/hadoop/hbase/regionserver/wal/TestWALActionsListener.java
* /hbase/trunk/hbase-server/src/test/java/org/apache/hadoop/hbase/regionserver/wal/TestWALReplay.java
* /hbase/trunk/hbase-server/src/test/java/org/apache/hadoop/hbase/replication/TestReplicationSource.java
* /hbase/trunk/hbase-server/src/test/java/org/apache/hadoop/hbase/replication/regionserver/TestReplicationSourceManager.java
* /hbase/trunk/hbase-server/src/test/java/org/apache/hadoop/hbase/util/TestMergeTool.java

                
> Run with > 1 WAL in HRegionServer
> ---------------------------------
>
>                 Key: HBASE-5699
>                 URL: https://issues.apache.org/jira/browse/HBASE-5699
>             Project: HBase
>          Issue Type: Improvement
>            Reporter: binlijin
>            Assignee: Li Pi
>         Attachments: PerfHbase.txt
>
>


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[jira] [Commented] (HBASE-5699) Run with > 1 WAL in HRegionServer

Posted by "Zhihong Yu (JIRA)" <ji...@apache.org>.
    [ https://issues.apache.org/jira/browse/HBASE-5699?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13268697#comment-13268697 ] 

Zhihong Yu commented on HBASE-5699:
-----------------------------------

bq. there is still a single "HLog" class, but underneath it would be multiple "SequenceFileLogWriters"
My approach is different from the above.
The new interface should be general enough that multi-HLog can be implemented without the requirement that HLog have multiple writers.
                
> Run with > 1 WAL in HRegionServer
> ---------------------------------
>
>                 Key: HBASE-5699
>                 URL: https://issues.apache.org/jira/browse/HBASE-5699
>             Project: HBase
>          Issue Type: Improvement
>            Reporter: binlijin
>            Assignee: Li Pi
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[jira] [Commented] (HBASE-5699) Run with > 1 WAL in HRegionServer

Posted by "Todd Lipcon (JIRA)" <ji...@apache.org>.
    [ https://issues.apache.org/jira/browse/HBASE-5699?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13265596#comment-13265596 ] 

Todd Lipcon commented on HBASE-5699:
------------------------------------

bq. Currently each HRegion has reference to the HLog it uses. If requests can be freely redirected to the HLog instance having fewer outstanding requests, the reference would be to that of the region server.

Sorry, I should be less free-wheeling with my terminology. My thought was that there is still a single "HLog" class, but underneath it would be multiple "SequenceFileLogWriters", most likely. Though maybe the correct implementation is to make HLog an interface, and then have a MultiHLog which wraps N other HLogs or something. Either way, any region would only have a reference to one "HLog" object, which might have more than one underlying stream.
                
> Run with > 1 WAL in HRegionServer
> ---------------------------------
>
>                 Key: HBASE-5699
>                 URL: https://issues.apache.org/jira/browse/HBASE-5699
>             Project: HBase
>          Issue Type: Improvement
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>            Assignee: Li Pi
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[jira] [Commented] (HBASE-5699) Run with > 1 WAL in HRegionServer

Posted by "binlijin (Commented) (JIRA)" <ji...@apache.org>.
    [ https://issues.apache.org/jira/browse/HBASE-5699?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13249664#comment-13249664 ] 

binlijin commented on HBASE-5699:
---------------------------------

@stack,
I run a test with 0.90 version use 10 writer and 3 nodes, some times it has double write performance, may be it not very well. 
                
> Run with > 1 WAL in HRegionServer
> ---------------------------------
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>                 Key: HBASE-5699
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[jira] [Commented] (HBASE-5699) Run with > 1 WAL in HRegionServer

Posted by "Li Pi (Commented) (JIRA)" <ji...@apache.org>.
    [ https://issues.apache.org/jira/browse/HBASE-5699?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13250471#comment-13250471 ] 

Li Pi commented on HBASE-5699:
------------------------------

This seems interesting. I'll take a look at doing this.
                
> Run with > 1 WAL in HRegionServer
> ---------------------------------
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[jira] [Commented] (HBASE-5699) Run with > 1 WAL in HRegionServer

Posted by "Zhihong Yu (JIRA)" <ji...@apache.org>.
    [ https://issues.apache.org/jira/browse/HBASE-5699?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13260008#comment-13260008 ] 

Zhihong Yu commented on HBASE-5699:
-----------------------------------

It was a duplicate message.
                
> Run with > 1 WAL in HRegionServer
> ---------------------------------
>
>                 Key: HBASE-5699
>                 URL: https://issues.apache.org/jira/browse/HBASE-5699
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>            Assignee: Li Pi
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[jira] [Commented] (HBASE-5699) Run with > 1 WAL in HRegionServer

Posted by "Zhihong Yu (JIRA)" <ji...@apache.org>.
    [ https://issues.apache.org/jira/browse/HBASE-5699?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13268039#comment-13268039 ] 

Zhihong Yu commented on HBASE-5699:
-----------------------------------

Are replication related unit tests passing ?

Since the review process would at least take a month, I think developing against a branch would be good practice.
                
> Run with > 1 WAL in HRegionServer
> ---------------------------------
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>                 Key: HBASE-5699
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[jira] [Assigned] (HBASE-5699) Run with > 1 WAL in HRegionServer

Posted by "Li Pi (Assigned) (JIRA)" <ji...@apache.org>.
     [ https://issues.apache.org/jira/browse/HBASE-5699?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Li Pi reassigned HBASE-5699:
----------------------------

    Assignee: Li Pi
    
> Run with > 1 WAL in HRegionServer
> ---------------------------------
>
>                 Key: HBASE-5699
>                 URL: https://issues.apache.org/jira/browse/HBASE-5699
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[jira] [Commented] (HBASE-5699) Run with > 1 WAL in HRegionServer

Posted by "Todd Lipcon (JIRA)" <ji...@apache.org>.
    [ https://issues.apache.org/jira/browse/HBASE-5699?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13293853#comment-13293853 ] 

Todd Lipcon commented on HBASE-5699:
------------------------------------

bq. I think we should wait for test result with HBASE-6116 before we invest more time in this.

HBASE-6116 seems like it would improve latency but hurt throughput -- on a typical gbit link, the parallel writes would limit us to 50M/sec for 3 replicas, whereas pipelined writes could give us 100M+.

The other main advantage of this JIRA is that the speed of the WAL is currently limited to the minimum speed of the 3 disks chosen in the pipeline. Given that disks can be heavily loaded, the probability of getting even a full disk's worth of throughput is low -- the likelihood is that at least one of those disks is also being written to or read from at least another client. So typically any single HDFS stream is limited to 35-40MB/sec in my experience.

Given that gbit is much faster than this, we can get better throughput by adding parallel WALs, so as to stripe across disks and dynamically push writes to less-loaded disks.
                
> Run with > 1 WAL in HRegionServer
> ---------------------------------
>
>                 Key: HBASE-5699
>                 URL: https://issues.apache.org/jira/browse/HBASE-5699
>             Project: HBase
>          Issue Type: Improvement
>            Reporter: binlijin
>            Assignee: Li Pi
>         Attachments: PerfHbase.txt
>
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[jira] [Commented] (HBASE-5699) Run with > 1 WAL in HRegionServer

Posted by "Zhihong Yu (JIRA)" <ji...@apache.org>.
    [ https://issues.apache.org/jira/browse/HBASE-5699?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13265521#comment-13265521 ] 

Zhihong Yu commented on HBASE-5699:
-----------------------------------

Trying to understand the implication of Todd's suggestion above.
Currently each HRegion has reference to the HLog it uses. If requests can be freely redirected to the HLog instance having fewer outstanding requests, the reference would be to that of the region server.
This means additional logic on region server for dispatching the write requests.
                
> Run with > 1 WAL in HRegionServer
> ---------------------------------
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>                 URL: https://issues.apache.org/jira/browse/HBASE-5699
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>            Assignee: Li Pi
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[jira] [Commented] (HBASE-5699) Run with > 1 WAL in HRegionServer

Posted by "Zhihong Yu (JIRA)" <ji...@apache.org>.
    [ https://issues.apache.org/jira/browse/HBASE-5699?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13268103#comment-13268103 ] 

Zhihong Yu commented on HBASE-5699:
-----------------------------------

This feature requires validation in real cluster.

@Jonathan:
Are you able to help Li in this regard ?

>From my experience in the past three weeks, development involves coding -> running test suite -> discovering defect through failed unit tests -> bug fixing -> validation through ycsb -> ...
                
> Run with > 1 WAL in HRegionServer
> ---------------------------------
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[jira] [Commented] (HBASE-5699) Run with > 1 WAL in HRegionServer

Posted by "Zhihong Yu (JIRA)" <ji...@apache.org>.
    [ https://issues.apache.org/jira/browse/HBASE-5699?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13268055#comment-13268055 ] 

Zhihong Yu commented on HBASE-5699:
-----------------------------------

Using trunk has the drawback that performance numbers (without this feature) gathered on day N may be obsolete by day N + 5, considering the amount of changes going into trunk.

I would suggest tackling replication as first priority. Dictionary WAL compression brought unexpected complexities w.r.t. replication. We shouldn't make replication any harder.

w.r.t. refactoring HLog into an interface, I tend to think that the interface should make different implementations possible.
If we only have one implementation, it is not easy to evaluate the effectiveness of the refactoring.
                
> Run with > 1 WAL in HRegionServer
> ---------------------------------
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>                 Key: HBASE-5699
>                 URL: https://issues.apache.org/jira/browse/HBASE-5699
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[jira] [Commented] (HBASE-5699) Run with > 1 WAL in HRegionServer

Posted by "Elliott Clark (JIRA)" <ji...@apache.org>.
    [ https://issues.apache.org/jira/browse/HBASE-5699?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13265112#comment-13265112 ] 

Elliott Clark commented on HBASE-5699:
--------------------------------------

Intuitively it seems like the number of WAL's that are used should be related to the number of spindles available to hbase.  So maybe this should be either a configurable number or something that is derived from the number of mount points hdfs is hosted on ?
                
> Run with > 1 WAL in HRegionServer
> ---------------------------------
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>                 Key: HBASE-5699
>                 URL: https://issues.apache.org/jira/browse/HBASE-5699
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[jira] [Updated] (HBASE-5699) Run with > 1 WAL in HRegionServer

Posted by "stack (Updated) (JIRA)" <ji...@apache.org>.
     [ https://issues.apache.org/jira/browse/HBASE-5699?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

stack updated HBASE-5699:
-------------------------

    Summary: Run with > 1 WAL in HRegionServer  (was: Should we use muti HLog or Writer in HLog in a HRegionServer)

Yes.  This topic comes up from time to time.  Would be nice to try it out.  It is possible to stand up the WAL subsystem on its own so you could experiment having HLog output to > 1 WAL.  A bunch of us would be interested in what you learn.
                
> Run with > 1 WAL in HRegionServer
> ---------------------------------
>
>                 Key: HBASE-5699
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[jira] [Commented] (HBASE-5699) Run with > 1 WAL in HRegionServer

Posted by "ramkrishna.s.vasudevan (JIRA)" <ji...@apache.org>.
    [ https://issues.apache.org/jira/browse/HBASE-5699?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13289370#comment-13289370 ] 

ramkrishna.s.vasudevan commented on HBASE-5699:
-----------------------------------------------

@Ted
The ycsb report we will get it tomorrow.  Today environemnt is busy.
@Lars
We will try to check HBASE-6116 also but not very sure if in the next couple of days. Anyway will try.
                
> Run with > 1 WAL in HRegionServer
> ---------------------------------
>
>                 Key: HBASE-5699
>                 URL: https://issues.apache.org/jira/browse/HBASE-5699
>             Project: HBase
>          Issue Type: Improvement
>            Reporter: binlijin
>            Assignee: Li Pi
>         Attachments: PerfHbase.txt
>
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[jira] [Commented] (HBASE-5699) Run with > 1 WAL in HRegionServer

Posted by "Zhihong Yu (JIRA)" <ji...@apache.org>.
    [ https://issues.apache.org/jira/browse/HBASE-5699?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13265128#comment-13265128 ] 

Zhihong Yu commented on HBASE-5699:
-----------------------------------

Currently I use the following knob for the maximum number of WAL's on an individual region server:
{code}
+    int totalInstances = conf.getInt("hbase.regionserver.hlog.total", DEFAULT_MAX_HLOG_INSTANCES);
{code}
                
> Run with > 1 WAL in HRegionServer
> ---------------------------------
>
>                 Key: HBASE-5699
>                 URL: https://issues.apache.org/jira/browse/HBASE-5699
>             Project: HBase
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>            Reporter: binlijin
>            Assignee: Li Pi
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[jira] [Commented] (HBASE-5699) Run with > 1 WAL in HRegionServer

Posted by "Lars Hofhansl (JIRA)" <ji...@apache.org>.
    [ https://issues.apache.org/jira/browse/HBASE-5699?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13279912#comment-13279912 ] 

Lars Hofhansl commented on HBASE-5699:
--------------------------------------

Good point.

Was referring to the general feature, not necessarily WAL/Region.
It's a trade off: Batching vs. parallel writes (just to state the obvious)

Do we batch beyond a region normally, though? Maybe during cache flush.

Yeah, WAL/Region with sync is probably not a good idea, there just won't be enough spindles in the HDFS cluster to absorb that.

So what's a good heuristic for the number of WALs? Maybe (assuming good block distribution and that HBase is the only user of the cluster) it should be around #spindles/#replicas...?

                
> Run with > 1 WAL in HRegionServer
> ---------------------------------
>
>                 Key: HBASE-5699
>                 URL: https://issues.apache.org/jira/browse/HBASE-5699
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[jira] [Commented] (HBASE-5699) Should we use muti HLog or Writer in HLog in a HRegionServer

Posted by "stack (Commented) (JIRA)" <ji...@apache.org>.
    [ https://issues.apache.org/jira/browse/HBASE-5699?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13244419#comment-13244419 ] 

stack commented on HBASE-5699:
------------------------------

Please provide more detail on what this issue is about and correct the subject so its properly spelled.  Thanks.
                
> Should we use muti HLog or Writer in HLog in a HRegionServer
> ------------------------------------------------------------
>
>                 Key: HBASE-5699
>                 URL: https://issues.apache.org/jira/browse/HBASE-5699
>             Project: HBase
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>            Reporter: binlijin
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[jira] [Updated] (HBASE-5699) Run with > 1 WAL in HRegionServer

Posted by "ramkrishna.s.vasudevan (JIRA)" <ji...@apache.org>.
     [ https://issues.apache.org/jira/browse/HBASE-5699?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

ramkrishna.s.vasudevan updated HBASE-5699:
------------------------------------------

    Attachment: PerfHbase.txt

Perf results. 
@Ted
The file attached also has the latency results. Run using LoadTestTool.  Sorry for being little late. Patch will upload later.
                
> Run with > 1 WAL in HRegionServer
> ---------------------------------
>
>                 Key: HBASE-5699
>                 URL: https://issues.apache.org/jira/browse/HBASE-5699
>             Project: HBase
>          Issue Type: Improvement
>            Reporter: binlijin
>            Assignee: Li Pi
>         Attachments: PerfHbase.txt
>
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[jira] [Commented] (HBASE-5699) Run with > 1 WAL in HRegionServer

Posted by "chunhui shen (Commented) (JIRA)" <ji...@apache.org>.
    [ https://issues.apache.org/jira/browse/HBASE-5699?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13249686#comment-13249686 ] 

chunhui shen commented on HBASE-5699:
-------------------------------------

I think the number of datanodes is a litte few in the test. Using double hlogWrites in RS, write performance should be nearly double except limit by the HDFS.
                
> Run with > 1 WAL in HRegionServer
> ---------------------------------
>
>                 Key: HBASE-5699
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[jira] [Commented] (HBASE-5699) Run with > 1 WAL in HRegionServer

Posted by "Zhihong Yu (JIRA)" <ji...@apache.org>.
    [ https://issues.apache.org/jira/browse/HBASE-5699?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13265076#comment-13265076 ] 

Zhihong Yu commented on HBASE-5699:
-----------------------------------

Playing with a prototype of this feature using ycsb (half insert, half upate) on a 5-node cluster where usertable has 13 regions on each region server.
Without this feature:
{code}
 10 sec: 99965 operations; 9996.5 current ops/sec; [UPDATE AverageLatency(us)=258.68] [INSERT AverageLatency(us)=610.28]
 20 sec: 99965 operations; 0 current ops/sec;
 25 sec: 99990 operations; 4.3 current ops/sec; [UPDATE AverageLatency(us)=2594303.62] [INSERT AverageLatency(us)=1240495.41]
[OVERALL], RunTime(ms), 25844.0
[OVERALL], Throughput(ops/sec), 3868.9831295465096
[UPDATE], Operations, 49935
[UPDATE], AverageLatency(us), 674.2635626314209
{code}
with this feature:
{code}
 10 sec: 99952 operations; 9994.2 current ops/sec; [UPDATE AverageLatency(us)=178.7] [INSERT AverageLatency(us)=584.76]
 20 sec: 99990 operations; 3.8 current ops/sec; [UPDATE AverageLatency(us)=10.88] [INSERT AverageLatency(us)=679174.27]
 20 sec: 99990 operations; 0 current ops/sec;
[OVERALL], RunTime(ms), 20867.0
[OVERALL], Throughput(ops/sec), 4791.776489193463
[UPDATE], Operations, 49992
[UPDATE], AverageLatency(us), 178.6439030244839
{code}
                
> Run with > 1 WAL in HRegionServer
> ---------------------------------
>
>                 Key: HBASE-5699
>                 URL: https://issues.apache.org/jira/browse/HBASE-5699
>             Project: HBase
>          Issue Type: Improvement
>            Reporter: binlijin
>            Assignee: Li Pi
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[jira] [Commented] (HBASE-5699) Run with > 1 WAL in HRegionServer

Posted by "Todd Lipcon (JIRA)" <ji...@apache.org>.
    [ https://issues.apache.org/jira/browse/HBASE-5699?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13279667#comment-13279667 ] 

Todd Lipcon commented on HBASE-5699:
------------------------------------

I think with durable sync, having a WAL-per-region would be even less feasible than it is today -- we currently depend on batching in order to get good throughput. If a server has 50 regions, then you'd get 50x less batching opportunity and write throughput would grind to a halt. Imagine a fan-out write to all of the regions -- it would generate 50 disk seeks instead of just 1.

                
> Run with > 1 WAL in HRegionServer
> ---------------------------------
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>                 Key: HBASE-5699
>                 URL: https://issues.apache.org/jira/browse/HBASE-5699
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[jira] [Commented] (HBASE-5699) Run with > 1 WAL in HRegionServer

Posted by "Zhihong Yu (JIRA)" <ji...@apache.org>.
    [ https://issues.apache.org/jira/browse/HBASE-5699?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13268789#comment-13268789 ] 

Zhihong Yu commented on HBASE-5699:
-----------------------------------

bq. If you have multiple hlogs do you use a different hlog in different regions?
Correct.

I have to go through legal procedure at my employer before disclosing my patch.
                
> Run with > 1 WAL in HRegionServer
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[jira] [Commented] (HBASE-5699) Run with > 1 WAL in HRegionServer

Posted by "Zhihong Yu (JIRA)" <ji...@apache.org>.
    [ https://issues.apache.org/jira/browse/HBASE-5699?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13265606#comment-13265606 ] 

Zhihong Yu commented on HBASE-5699:
-----------------------------------

bq. to one "HLog" object, which might have more than one underlying stream.
The above can be a (sub-)task by itself.

                
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[jira] [Commented] (HBASE-5699) Run with > 1 WAL in HRegionServer

Posted by "Zhihong Yu (JIRA)" <ji...@apache.org>.
    [ https://issues.apache.org/jira/browse/HBASE-5699?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13278927#comment-13278927 ] 

Zhihong Yu commented on HBASE-5699:
-----------------------------------

@Ramkrishna:
Your numbers look better than mine though the mix in my case was 50% updates and 50% puts.

Can you publish latency numbers as well ?
                
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[jira] [Commented] (HBASE-5699) Run with > 1 WAL in HRegionServer

Posted by "Lars Hofhansl (JIRA)" <ji...@apache.org>.
    [ https://issues.apache.org/jira/browse/HBASE-5699?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13400559#comment-13400559 ] 

Lars Hofhansl commented on HBASE-5699:
--------------------------------------

Assuming Datanodes and RegionServers are colocated no more bits will have to cross the (aggregate) "wires". Further assuming good load balancing within HBase the net bandwidth is still spread over the cluster (but with lower latency at each RegionServer).
So I do not believe that HBASE-6116 will actually hurt performance.

The key question is whether WAL writing is mostly bound by latency or bandwidth (And I do not know.)
Do we get 35-40mb throughput from writing the WAL? If not, it is likely bound by latency.
                
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[jira] [Commented] (HBASE-5699) Run with > 1 WAL in HRegionServer

Posted by "Jean-Daniel Cryans (JIRA)" <ji...@apache.org>.
    [ https://issues.apache.org/jira/browse/HBASE-5699?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13265167#comment-13265167 ] 

Jean-Daniel Cryans commented on HBASE-5699:
-------------------------------------------

bq. Intuitively it seems like the number of WAL's that are used should be related to the number of spindles available to hbase.

I disagree, considering that most of the deployments have rep=3 you're using three spindles not one. The multiplying effect could generate a lot of disk seeks since the WALs are competing like that (plus flushing, compacting, etc).
                
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[jira] [Updated] (HBASE-5699) Run with > 1 WAL in HRegionServer

Posted by "Zhihong Yu (JIRA)" <ji...@apache.org>.
     [ https://issues.apache.org/jira/browse/HBASE-5699?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Zhihong Yu updated HBASE-5699:
------------------------------

    Comment: was deleted

(was: This seems interesting. I'll take a look at doing this.)
    
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[jira] [Commented] (HBASE-5699) Run with > 1 WAL in HRegionServer

Posted by "ramkrishna.s.vasudevan (JIRA)" <ji...@apache.org>.
    [ https://issues.apache.org/jira/browse/HBASE-5699?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13278615#comment-13278615 ] 

ramkrishna.s.vasudevan commented on HBASE-5699:
-----------------------------------------------

We are also interested in this.
Worked on a prototype with having one HLog instance but underlying there will be multiple writer instances.  The regions will be allocated with any one of the writer instance and each region will be writing to hlog using the instance associated with it.

Even on logrolling the instances against each region will be updated and the region will continue to use its mapping.
Without patch 
~53K puts/sec.

With patch
~78-80k puts/sec

It is a 3 node cluster and the size of each record was 1k. No of regions : 2800
By default used 3 writer instances.  I was able to pass the testcases related to TestHlog and TestDistributedLogSplitting. But Testmasterreplication was not passing.
Replication needs some change based on this which i did not work on much.

The pendingWrites list that we use is now converted into a map having the writer with the list of pending writes.

Pls provide your suggestions on this.  
BTW, Li Pi, any progress on this? I would love to help you in this.  
May be i can prepare a more forma patch and upload over here.

                
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[jira] [Commented] (HBASE-5699) Run with > 1 WAL in HRegionServer

Posted by "binlijin (Commented) (JIRA)" <ji...@apache.org>.
    [ https://issues.apache.org/jira/browse/HBASE-5699?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13250374#comment-13250374 ] 

binlijin commented on HBASE-5699:
---------------------------------

I just run a test and don't test the recovery and the others.
                
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[jira] [Commented] (HBASE-5699) Run with > 1 WAL in HRegionServer

Posted by "Lars Hofhansl (JIRA)" <ji...@apache.org>.
    [ https://issues.apache.org/jira/browse/HBASE-5699?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13288699#comment-13288699 ] 

Lars Hofhansl commented on HBASE-5699:
--------------------------------------

@Ted or @Ram: If you have any chance to test HBASE-6116 as well, that'd be really cool (although it would be more effort, as it only works against Hadoop trunk - and soon Hadoop 2.0-alpha).
Andy said he might test against EC2.
                
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[jira] [Commented] (HBASE-5699) Run with > 1 WAL in HRegionServer

Posted by "Jonathan Hsieh (JIRA)" <ji...@apache.org>.
    [ https://issues.apache.org/jira/browse/HBASE-5699?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13268786#comment-13268786 ] 

Jonathan Hsieh commented on HBASE-5699:
---------------------------------------

Zhihong, I'm curious to learn about the approach you have taken in the prototype that you have.  Is it on github somewhere perhaps?

If you have multiple hlogs do you use a different hlog in different regions?  
Do you have a shim that looks like an hlog but has two hlogs inside it (as opposed to hdfs file handles)?

                
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[jira] [Commented] (HBASE-5699) Run with > 1 WAL in HRegionServer

Posted by "Jonathan Hsieh (JIRA)" <ji...@apache.org>.
    [ https://issues.apache.org/jira/browse/HBASE-5699?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13265565#comment-13265565 ] 

Jonathan Hsieh commented on HBASE-5699:
---------------------------------------

Part of the motivation for multiple wals can be found in this tech talk: (most relavent to HBase is backup requests, starting slide 39)

http://static.googleusercontent.com/external_content/untrusted_dlcp/research.google.com/en/us/people/jeff/Berkeley-Latency-Mar2012.pdf
                
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[jira] [Commented] (HBASE-5699) Run with > 1 WAL in HRegionServer

Posted by "stack (JIRA)" <ji...@apache.org>.
    [ https://issues.apache.org/jira/browse/HBASE-5699?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13260020#comment-13260020 ] 

stack commented on HBASE-5699:
------------------------------

@Ted Would suggest you just leave it. When you delete, we all get a message in our mailbox about the delete transaction.  Then we start to wonder...
                
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[jira] [Commented] (HBASE-5699) Run with > 1 WAL in HRegionServer

Posted by "stack (Commented) (JIRA)" <ji...@apache.org>.
    [ https://issues.apache.org/jira/browse/HBASE-5699?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13249902#comment-13249902 ] 

stack commented on HBASE-5699:
------------------------------

@binlijin What Chunhui says.  I'd think that if it were a bigger cluster you'd see a more marked improvement.  What about recovery?  How does log splitting work with all the extra WALs?
                
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[jira] [Commented] (HBASE-5699) Should we use muti HLog or Writer in HLog in a HRegionServer

Posted by "binlijin (Commented) (JIRA)" <ji...@apache.org>.
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binlijin commented on HBASE-5699:
---------------------------------

@stack, 
There is only one HLog and a Writer in a HRegionServer for write-ahead-log, at any time only one writer takes the HLog lock and the other will wait. If there are muti HLog or Writer, the write-ahead-log can be run parallel, the write performance should be improved.  
                
> Should we use muti HLog or Writer in HLog in a HRegionServer
> ------------------------------------------------------------
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[jira] [Comment Edited] (HBASE-5699) Run with > 1 WAL in HRegionServer

Posted by "Lars Hofhansl (JIRA)" <ji...@apache.org>.
    [ https://issues.apache.org/jira/browse/HBASE-5699?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13279661#comment-13279661 ] 

Lars Hofhansl edited comment on HBASE-5699 at 5/20/12 4:49 AM:
---------------------------------------------------------------

I suspect this will become more important when people eventually turn on HBASE-5954 (durable sync, if they don't run in data centers with backup power supplies).

bq. There would be many regions in a cluster. They may not receive even write load.

Is that necessarily a problem? Just saying that while we are exploring this, might as well explore this option as well. I for one be happy if a region's edits are tied to that region and log splitting could just go away (well almost, would still need to split if the region is split).

                
      was (Author: lhofhansl):
    I suspect this will become more important when people eventually turn on HBASE-5954 (durable sync, if they don't in data centers with backup power supplies).

bq. There would be many regions in a cluster. They may not receive even write load.

Is that necessarily a problem? Just saying that while we are exploring this, might as well explore this option as well. I for one be happy if a region's edits are tied to that region and log splitting could just go away (well almost, would still need to split if the region is split).

                  
> Run with > 1 WAL in HRegionServer
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[jira] [Commented] (HBASE-5699) Run with > 1 WAL in HRegionServer

Posted by "Li Pi (JIRA)" <ji...@apache.org>.
    [ https://issues.apache.org/jira/browse/HBASE-5699?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13279289#comment-13279289 ] 

Li Pi commented on HBASE-5699:
------------------------------

My design is a bit different. Ill upload a patch soon. I'm doing any region
to any blog. Currently distributed log splitting and replication do not
work yet.


                
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[jira] [Commented] (HBASE-5699) Run with > 1 WAL in HRegionServer

Posted by "stack (JIRA)" <ji...@apache.org>.
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stack commented on HBASE-5699:
------------------------------

@Ted Why delete a comment, especially someone elses?
                
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[jira] [Commented] (HBASE-5699) Run with > 1 WAL in HRegionServer

Posted by "Lars Hofhansl (JIRA)" <ji...@apache.org>.
    [ https://issues.apache.org/jira/browse/HBASE-5699?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13279661#comment-13279661 ] 

Lars Hofhansl commented on HBASE-5699:
--------------------------------------

I suspect this will become more important when people eventually turn on HBASE-5954 (durable sync, if they don't in data centers with backup power supplies).

bq. There would be many regions in a cluster. They may not receive even write load.

Is that necessarily a problem? Just saying that while we are exploring this, might as well explore this option as well. I for one be happy if a region's edits are tied to that region and log splitting could just go away (well almost, would still need to split if the region is split).

                
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[jira] [Issue Comment Edited] (HBASE-5699) Should we use muti HLog or Writer in HLog in a HRegionServer

Posted by "stack (Issue Comment Edited) (JIRA)" <ji...@apache.org>.
    [ https://issues.apache.org/jira/browse/HBASE-5699?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13244419#comment-13244419 ] 

stack edited comment on HBASE-5699 at 4/2/12 6:48 PM:
------------------------------------------------------

Please provide more detail on what this issue is about and correct the subject so it's properly spelled.  Thanks.
                
      was (Author: stack):
    Please provide more detail on what this issue is about and correct the subject so its properly spelled.  Thanks.
                  
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[jira] [Commented] (HBASE-5699) Run with > 1 WAL in HRegionServer

Posted by "Li Pi (JIRA)" <ji...@apache.org>.
    [ https://issues.apache.org/jira/browse/HBASE-5699?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13268048#comment-13268048 ] 

Li Pi commented on HBASE-5699:
------------------------------

Replication is the failure point. I haven't really worked on that yet.

Talked to Jon about the dev process. I'll create a seperate Jira for refactoring HLog into an interface. I'll probably continue to work within trunk. 

Separate JIRA should make things easier though.
                
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[jira] [Commented] (HBASE-5699) Run with > 1 WAL in HRegionServer

Posted by "Zhihong Ted Yu (JIRA)" <ji...@apache.org>.
    [ https://issues.apache.org/jira/browse/HBASE-5699?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13293517#comment-13293517 ] 

Zhihong Ted Yu commented on HBASE-5699:
---------------------------------------

As I mentioned in HBASE-6055 @ 04/Jun/12 17:47, one of the benefits of this feature is for each HLog file to receive edits for one single table.
                
> Run with > 1 WAL in HRegionServer
> ---------------------------------
>
>                 Key: HBASE-5699
>                 URL: https://issues.apache.org/jira/browse/HBASE-5699
>             Project: HBase
>          Issue Type: Improvement
>            Reporter: binlijin
>            Assignee: Li Pi
>         Attachments: PerfHbase.txt
>
>


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[jira] [Commented] (HBASE-5699) Run with > 1 WAL in HRegionServer

Posted by "Li Pi (JIRA)" <ji...@apache.org>.
    [ https://issues.apache.org/jira/browse/HBASE-5699?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13268101#comment-13268101 ] 

Li Pi commented on HBASE-5699:
------------------------------

While performance numbers will change, you can simply test with MultipleHLogs on and MultipleHLogsoff. I don't think we're going to move everyone over to multiple Hlogs immediately.

Will take a look at those tests.
                
> Run with > 1 WAL in HRegionServer
> ---------------------------------
>
>                 Key: HBASE-5699
>                 URL: https://issues.apache.org/jira/browse/HBASE-5699
>             Project: HBase
>          Issue Type: Improvement
>            Reporter: binlijin
>            Assignee: Li Pi
>


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[jira] [Commented] (HBASE-5699) Run with > 1 WAL in HRegionServer

Posted by "Lars Hofhansl (JIRA)" <ji...@apache.org>.
    [ https://issues.apache.org/jira/browse/HBASE-5699?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13293471#comment-13293471 ] 

Lars Hofhansl commented on HBASE-5699:
--------------------------------------

I think we should wait for test result with HBASE-6116 before we invest more time in this.
My gut feeling tells me, that is something that is better handled at the HDFS level.
                
> Run with > 1 WAL in HRegionServer
> ---------------------------------
>
>                 Key: HBASE-5699
>                 URL: https://issues.apache.org/jira/browse/HBASE-5699
>             Project: HBase
>          Issue Type: Improvement
>            Reporter: binlijin
>            Assignee: Li Pi
>         Attachments: PerfHbase.txt
>
>


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[jira] [Commented] (HBASE-5699) Run with > 1 WAL in HRegionServer

Posted by "Zhihong Ted Yu (JIRA)" <ji...@apache.org>.
    [ https://issues.apache.org/jira/browse/HBASE-5699?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13288592#comment-13288592 ] 

Zhihong Ted Yu commented on HBASE-5699:
---------------------------------------

Can you run ycsb with 50% insert and 50% update load ?
Performance numbers in attachment match what I got based on my implementation.

Thanks
                
> Run with > 1 WAL in HRegionServer
> ---------------------------------
>
>                 Key: HBASE-5699
>                 URL: https://issues.apache.org/jira/browse/HBASE-5699
>             Project: HBase
>          Issue Type: Improvement
>            Reporter: binlijin
>            Assignee: Li Pi
>         Attachments: PerfHbase.txt
>
>


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[jira] [Commented] (HBASE-5699) Run with > 1 WAL in HRegionServer

Posted by "Li Pi (JIRA)" <ji...@apache.org>.
    [ https://issues.apache.org/jira/browse/HBASE-5699?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13268216#comment-13268216 ] 

Li Pi commented on HBASE-5699:
------------------------------

I thought about the compression bit already. I was going to compress each separate log individually.

Yeah, I should have probably wrote up what I was going to do before hacking stuff up. Will switch gears and work on that a bit instead.
                
> Run with > 1 WAL in HRegionServer
> ---------------------------------
>
>                 Key: HBASE-5699
>                 URL: https://issues.apache.org/jira/browse/HBASE-5699
>             Project: HBase
>          Issue Type: Improvement
>            Reporter: binlijin
>            Assignee: Li Pi
>


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[jira] [Commented] (HBASE-5699) Run with > 1 WAL in HRegionServer

Posted by "stack (JIRA)" <ji...@apache.org>.
    [ https://issues.apache.org/jira/browse/HBASE-5699?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13268110#comment-13268110 ] 

stack commented on HBASE-5699:
------------------------------

@Li You should be able to work whereever you like if you make up an harness for running hlog implementations apart from hbase.  This should be first order of business (unless you are a masochist).  Should be easy enough, if its not possible already, especially after you make it pluggable.

Regards... "I'm assuming we don't need to guarantee HLog edit sequencing. If we do, this becomes a bit harder." -- well thats the way it is currently so onus will be on you to come up a reason why it could be otherwise. In-order makes it easier to reason about whether or not all edits up to a particular sequence id have been sync'd or not.

And don't forget the other side of the moon, the (distributed) log splitting story.  That needs to work too after you are done.
                
> Run with > 1 WAL in HRegionServer
> ---------------------------------
>
>                 Key: HBASE-5699
>                 URL: https://issues.apache.org/jira/browse/HBASE-5699
>             Project: HBase
>          Issue Type: Improvement
>            Reporter: binlijin
>            Assignee: Li Pi
>


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