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https://issues.apache.org/jira/browse/HBASE-3899?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13070891#comment-13070891
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[email protected] commented on HBASE-3899:
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This is an automatically generated e-mail. To reply, visit:
https://reviews.apache.org/r/1174/
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(Updated 2011-07-26 01:19:52.655737)
Review request for hbase.
Changes
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* Add checking for number of calls currently delayed. A warning message is
issued if too many calls are delayed.
* Unit test to check that above warning works.
* endDelay() now takes an Object as a parameter, not a Writable. Initially, I
thought the method that ended the delay should pack the response (i.e.
endDelay(new HbaseObjectWritable(retval))), but it makes more sense to pack it
in setResponse.
* Address other feedback from Todd Lipcon. Thanks!
Summary
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Free up RPC server Handler thread if the called routine specifies the call
should be delayed. The RPC client sees no difference, changes are server-side
only. This is based on the previous submitted patch from Dhruba.
This addresses bug HBASE-3899.
https://issues.apache.org/jira/browse/HBASE-3899
Diffs (updated)
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src/main/java/org/apache/hadoop/hbase/ipc/Delayable.java PRE-CREATION
src/main/java/org/apache/hadoop/hbase/ipc/HBaseServer.java 61d3915
src/main/java/org/apache/hadoop/hbase/ipc/RpcServer.java 0da7f9e
src/test/java/org/apache/hadoop/hbase/ipc/TestDelayedRpc.java PRE-CREATION
Diff: https://reviews.apache.org/r/1174/diff
Testing
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Unit tests run. Also, the patch includes a new unit test.
Thanks,
Vlad
> enhance HBase RPC to support free-ing up server handler threads even if
> response is not ready
> ---------------------------------------------------------------------------------------------
>
> Key: HBASE-3899
> URL: https://issues.apache.org/jira/browse/HBASE-3899
> Project: HBase
> Issue Type: Improvement
> Components: ipc
> Reporter: dhruba borthakur
> Assignee: dhruba borthakur
> Fix For: 0.94.0
>
> Attachments: HBASE-3899.patch, asyncRpc.txt, asyncRpc.txt
>
>
> In the current implementation, the server handler thread picks up an item
> from the incoming callqueue, processes it and then wraps the response as a
> Writable and sends it back to the IPC server module. This wastes
> thread-resources when the thread is blocked for disk IO (transaction logging,
> read into block cache, etc).
> It would be nice if we can make the RPC Server Handler threads pick up a call
> from the IPC queue, hand it over to the application (e.g. HRegion), the
> application can queue it to be processed asynchronously and send a response
> back to the IPC server module saying that the response is not ready. The RPC
> Server Handler thread is now ready to pick up another request from the
> incoming callqueue. When the queued call is processed by the application, it
> indicates to the IPC module that the response is now ready to be sent back to
> the client.
> The RPC client continues to experience the same behaviour as before. A RPC
> client is synchronous and blocks till the response arrives.
> This RPC enhancement allows us to do very powerful things with the
> RegionServer. In future, we can make enhance the RegionServer's threading
> model to a message-passing model for better performance. We will not be
> limited by the number of threads in the RegionServer.
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