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https://issues.apache.org/jira/browse/AMBARI-17248?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15335214#comment-15335214
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Hadoop QA commented on AMBARI-17248:
------------------------------------

{color:green}+1 overall{color}.  Here are the results of testing the latest 
attachment 
  
http://issues.apache.org/jira/secure/attachment/12811144/AMBARI-17248.trunk.v3.patch
  against trunk revision .

    {color:green}+1 @author{color}.  The patch does not contain any @author 
tags.

    {color:green}+1 tests included{color}.  The patch appears to include 3 new 
or modified test files.

    {color:green}+1 javac{color}.  The applied patch does not increase the 
total number of javac compiler warnings.

    {color:green}+1 release audit{color}.  The applied patch does not increase 
the total number of release audit warnings.

    {color:green}+1 core tests{color}.  The patch passed unit tests in 
ambari-server.

Test results: 
https://builds.apache.org/job/Ambari-trunk-test-patch/7390//testReport/
Console output: 
https://builds.apache.org/job/Ambari-trunk-test-patch/7390//console

This message is automatically generated.

> Reduce the idle time before first command from next stage is executed on a 
> host
> -------------------------------------------------------------------------------
>
>                 Key: AMBARI-17248
>                 URL: https://issues.apache.org/jira/browse/AMBARI-17248
>             Project: Ambari
>          Issue Type: Improvement
>          Components: ambari-agent, ambari-server
>            Reporter: Sebastian Toader
>            Assignee: Sebastian Toader
>             Fix For: 2.4.0
>
>         Attachments: AMBARI-17248.trunk.v3.patch
>
>
> Commands to be executed by ambari-agents are being sent down by the server in 
> the response message to agent heartbeat messages. 
> The server processes the received heartbeat, it checks if there are next 
> commands scheduled to be executed by ambari-agent and adds those to the 
> heartbeat response for the ambari-agent.
> The server organises the commands that can be executed in parallel into 
> stages. Ambari server ensures that only the commands of a single stage is 
> scheduled to be executed by the agent and starts scheduling the commands of 
> the next stage only after all commands of current stage has finished 
> successfully.
> The processing of command status received with the heartbeat message happens 
> asynchronously to heartbeat response in HeartBeatProcessor and 
> ActionScheduler creation thus when the heartbeat response is created the 
> commands for the next stage are not scheduled yet. This means that the next 
> commands will be sent to agent only with the next heartbeat.
> Agents currently sends a heartbeat to the server on command a completion or 
> at a timeout = self.netutil.HEARTBEAT_IDDLE_INTERVAL_SEC – 
> self.netutil.MINIMUM_INTERVAL_BETWEEN_HEARTBEATS interval which is ~10 
> seconds if there are no commands to be executed.
> This means that when the server receives a heartbeat triggered by the 
> completion of the last command from the current stage the server will send 
> the commands for the next stage only 10 seconds later when the next heartbeat 
> is received. This leads to agents spending considerable amount of time idle 
> when there are multiple stages to be executed.
> Agents should heartbeat at a higher rate while there are still pending stages 
> to be executed.



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