[jira] [Commented] (MESOS-1607) Introduce optimistic offers.

["Liqiang Lin (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/MESOS-1607?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14738431#comment-14738431 ] 

Liqiang Lin commented on MESOS-1607:
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Is there any design doc I can get?

If it's optimistic offer, who will resolve the resource conflict in accepting offer? Allocator or Mesos master? I think sending run task message should be after resolving resource conflict. If it's allocator's responsibility to resolve resource conflict, will a new interface in allocator be introduced? If yes, how this new interface interact with existing recoverResources() function?

Please append more design about how to resolve resource conflict in accepting offer.
Thanks

> Introduce optimistic offers.
> ----------------------------
>
>                 Key: MESOS-1607
>                 URL: https://issues.apache.org/jira/browse/MESOS-1607
>             Project: Mesos
>          Issue Type: Epic
>          Components: allocation, framework, master
>            Reporter: Benjamin Hindman
>         Attachments: optimisitic-offers.pdf
>
>
> The current implementation of resource offers only enable a single framework scheduler to make scheduling decisions for some available resources at a time. In some circumstances, this is good, i.e., when we don't want other framework schedulers to have access to some resources. However, in other circumstances, there are advantages to letting multiple framework schedulers attempt to make scheduling decisions for the _same_ allocation of resources in parallel.
> If you think about this from a "concurrency control" perspective, the current implementation of resource offers is _pessimistic_, the resources contained within an offer are _locked_ until the framework scheduler that they were offered to launches tasks with them or declines them. In addition to making pessimistic offers we'd like to give out _optimistic_ offers, where the same resources are offered to multiple framework schedulers at the same time, and framework schedulers "compete" for those resources on a first-come-first-serve basis (i.e., the first to launch a task "wins"). We've always reserved the right to rescind resource offers using the 'rescind' primitive in the API, and a framework scheduler should be prepared to launch a task and have those tasks go lost because another framework already started to use those resources.
> Introducing optimistic offers will enable more sophisticated allocation algorithms. For example, we can optimistically allocate resources that are reserved for a particular framework (role) but are not being used. In conjunction with revocable resources (the concept that using resources not reserved for you means you might get those resources revoked) we can easily create a "spot" market for unused resources, driving up utilization by letting frameworks that are willing to use revocable resources run tasks.
> In the limit, one could imagine always making optimistic resource offers. This bears a striking resemblance with the Google Omega model (an isomorphism even). However, being able to configure what resources should be allocated optimistically and what resources should be allocated pessimistically gives even more control to a datacenter/cluster operator that might want to, for example, never let multiple frameworks (roles) compete for some set of resources.



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