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https://issues.apache.org/jira/browse/MESOS-9277?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16649340#comment-16649340
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Alexander Rukletsov commented on MESOS-9277:
--------------------------------------------
IIUC, scheduler API is a stream hence using {{process::Sequence}} should be
sufficient.
> UNRESERVE scheduler call be dropped if it loses the race with TEARDOWN.
> ------------------------------------------------------------------------
>
> Key: MESOS-9277
> URL: https://issues.apache.org/jira/browse/MESOS-9277
> Project: Mesos
> Issue Type: Bug
> Components: scheduler api
> Affects Versions: 1.5.1, 1.6.1, 1.7.0
> Reporter: Alexander Rukletsov
> Priority: Major
> Labels: mesosphere, v1_api
>
> A typical use pattern for a framework scheduler is to remove its reservations
> before tearing itself down. However, it is racy: {{UNRESERVE}} is a
> multi-stage action which aborts if the framework is removed in-between.
> *Solution 1*
> Let schedulers use operation feedback and expect them to wait for an ack for
> {{UNRESERVE}} before they send {{TEARDOWN}}. Kind of science fiction with a
> timeline of {{O(months)}} and still possibilities for the race if a scheduler
> does not comply.
> *Solution 2*
> Serialize calls for schedulers. For example, we can chain [handlers
> here|https://github.com/apache/mesos/blob/6e21e94ddca5b776d44636fe3eba8500bf88dc25/src/master/http.cpp#L640-L711]
> onto per-{{Master::Framework}}
> [{{process::Sequence}}|https://github.com/apache/mesos/blob/6e21e94ddca5b776d44636fe3eba8500bf88dc25/3rdparty/libprocess/include/process/sequence.hpp].
> For that however, handlers must provide futures indicating when the
> processing of the call is finished, note that most [handlers
> here|https://github.com/apache/mesos/blob/6e21e94ddca5b776d44636fe3eba8500bf88dc25/src/master/http.cpp#L640-L711]
> return void.
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