[jira] [Commented] (OOZIE-3382) Optimize SshActionExecutor's drainBuffers method

["Hadoop QA (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/OOZIE-3382?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16693098#comment-16693098 ] 

Hadoop QA commented on OOZIE-3382:
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PreCommit-OOZIE-Build started


> Optimize SshActionExecutor's drainBuffers method
> ------------------------------------------------
>
>                 Key: OOZIE-3382
>                 URL: https://issues.apache.org/jira/browse/OOZIE-3382
>             Project: Oozie
>          Issue Type: Improvement
>            Reporter: Andras Salamon
>            Assignee: Andras Salamon
>            Priority: Major
>         Attachments: OOZIE-3382-01.patch
>
>
> OOZIE-3354 improved {{SshActionExecutor}} to avoid {{Process#waitFor()}} blocks and modified the {{drainBuffers}} method to keep draining the standard output (and standard error) continuously.
> Right now the speed of the drain is hardwired. As long as the process is running the method only reads 1024 bytes in each cycle (half a second) which can take very long time if we want to drain several megabytes (for instance {{oozie.servlet.CallbackServlet.max.data.len}} is increased).
> Let's optimize the draining.
> We can either read 1024 bytes multiple times in each cycle (as long as there are data in the buffer), or we can increase the value of the buffer size (1024). 
> In the latter case the default of the buffer size could be half of the {{oozie.servlet.CallbackServlet.max.data.len}} value, but we also need an additional property to specify the buffer size (to avoid memory problems because of using a very big buffer). We can keep 1024 as a minimum buffer size. 
> It would be also useful to refactor the code and put the buffer draining into a separate class and create unit tests for the class. Using this class in {{ShellMain}} to avoid code duplication would also be very useful, but we have to fix OOZIE-3359 first.



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