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https://issues.apache.org/jira/browse/HBASE-16583?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15489838#comment-15489838
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Phil Yang commented on HBASE-16583:
-----------------------------------

Change to a more general name. After HBASE-16505 the interface of Region will 
be changed to asynchronous and returns CompletableFuture, but implementation in 
HRegion is still synchronous at first. We should find an appropriate method to 
make them async. 

> Make Region's implementation asynchronous
> -----------------------------------------
>
>                 Key: HBASE-16583
>                 URL: https://issues.apache.org/jira/browse/HBASE-16583
>             Project: HBase
>          Issue Type: Umbrella
>            Reporter: Phil Yang
>
> Staged Event-Driven Architecture (SEDA) splits request-handling logic into 
> several stages, each stage is executed in a thread pool and they are 
> connected by queues.
> Currently, in region server we use a thread pool to handle requests from 
> client. The number of handlers is configurable, reading and writing use 
> different pools. The current architecture has two limitations:
> Performance:
> Different part of the handling path has different bottleneck. For example, 
> accessing MemStore and cache mainly consumes CPU but accessing HDFS mainly 
> consumes network/disk IO. If we use SEDA and split them into two different 
> stages, we can use different numbers for two pools according to the 
> CPU/disk/network performance case by case.
> Availability:
> HBASE-16388 described a scene that if the client use a thread pool and use 
> blocking methods to access region servers, only one slow server may exhaust 
> most of threads of the client. For HBase, we are the client and HDFS 
> datanodes are the servers. A slow datanode may exhaust most of handlers. The 
> best way to resolve this issue is make HDFS requests non-blocking, which is 
> exactly what SEDA does.



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