[jira] [Commented] (HBASE-6968) Several HBase write perf improvement

["ramkrishna.s.vasudevan (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/HBASE-6968?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13472978#comment-13472978 ] 

ramkrishna.s.vasudevan commented on HBASE-6968:
-----------------------------------------------

Nice one.
                
> Several HBase write perf improvement
> ------------------------------------
>
>                 Key: HBASE-6968
>                 URL: https://issues.apache.org/jira/browse/HBASE-6968
>             Project: HBase
>          Issue Type: Improvement
>            Reporter: Liyin Tang
>
> Here are 2 hbase write performance improvements recently:
> 1) Avoid creating HBaseConfiguraiton object for each HLog. Every time when creating a HBaseConfiguraiton object, it would parse the xml configuration files from disk, which is not cheap operation.
> In HLog.java:
> orig:
> {code:title=HLog.java}
>   newWriter = createWriter(fs, newPath, HBaseConfiguration.create(conf));
> {code}
> new:
> {code}
>   newWriter = createWriter(fs, newPath, conf);
> {code}
> 2) Change 2 hotspot synchronized functions into double locking pattern. So it shall remove the synchronization overhead in the normal case.
> orig:
> {code:title=HBaseRpcMetrics.java}
>   public synchronized void inc(String name, int amt) {	
>     MetricsTimeVaryingRate m = get(name);	
>     if (m == null) {	
>       m = create(name);	
>     }	
>     m.inc(amt);	
>   }
> {code}
> new:
> {code}
>   public void inc(String name, int amt) {	
>     MetricsTimeVaryingRate m = get(name);	
>     if (m == null) {	
>       synchronized (this) {	
>         if ((m = get(name)) == null) {	
>           m = create(name);	
>         }	
>       }	
>     }	
>     m.inc(amt);	
>   }
> {code}
> =====================
> orig:
> {code:title=MemStoreFlusher.java}
>   public synchronized void reclaimMemStoreMemory() {	
>     if (this.server.getGlobalMemstoreSize().get() >= globalMemStoreLimit) {	
>       flushSomeRegions();	
>     }
>   }	
> {code}
> new:
> {code}
>   public void reclaimMemStoreMemory() {	
>     if (this.server.getGlobalMemstoreSize().get() >= globalMemStoreLimit) {	
>       flushSomeRegions();	
>     }
>   }	
>   private synchronized void flushSomeRegions() {	
>     if (this.server.getGlobalMemstoreSize().get() < globalMemStoreLimit) {	
>       return; // double check the global memstore size inside of the synchronized block.	
>     }	
>  ...   
>  }
> {code}

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