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https://issues.apache.org/jira/browse/SLIDER-1066?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15113211#comment-15113211
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Steve Loughran commented on SLIDER-1066:
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when it flexes up, it just asks YARN for more containers, and waits for them to
be allocated. Similarly, on flex down, it decides which ones to release and
discards them.
The code that reacts to flex up is exactly the same as that which responds to
container failure: count the number of containers, add the number being
requested, subtract the number being released, and we then have the "current"
set. Compare the current count with that of the desired value: if fewer —ask
for more. If too many —release.
> Make AM restart during upgrade option - e.g. via a option to upgrade command
> ----------------------------------------------------------------------------
>
> Key: SLIDER-1066
> URL: https://issues.apache.org/jira/browse/SLIDER-1066
> Project: Slider
> Issue Type: Improvement
> Affects Versions: Slider 0.80, Slider 0.90.2
> Reporter: Manoj Samel
>
> During "slider upgrade" command e.g. to add a new component; the slider AM
> itself restarts.
> One slide use case is deploy a service via slider and create a new component
> for every new user of service. New components are added via "slider upgrade"
> so existing components (i.e. users) are not impacted by down time. During
> each component upgrade the AM also restarts and all existing components have
> to know the new AM before they can heartbeat to it.
> Per discussions, the AM restart during upgrade is being done to pick up new
> Yarn parameters.
> However, in this use case, Hadoop cluster yarn parameters are not being
> changed; neither are parameters to any of the existing components. Thus the
> AM restart in this case seems to provide no benefit - though it brings a
> small risk that any issue in AM restart will shut down the entire application
> (i.e. impact all running users).
> An option should be provided during the upgrade to NOT do AM restart -
> allowing users of slider to have a choice.
> Filing the improvement Jira per discussion on d-list.
> Thanks,
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