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https://issues.apache.org/jira/browse/MESOS-6090?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15437589#comment-15437589
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Vinod Kone commented on MESOS-6090:
-----------------------------------
Just so that I understand, currently
registration path:
-----------------------
added to "registering" --> registry operation --> moved to "registered"
re-registration path:
-------------------------
added to "reregistering" --> registry operation --> moved to "registered"
removal path
-----------------
added to "removing" --> registry operation --> doesn't appear in any maps
(could've been moved to "removed" here instead?)
this seems easy enough to understand? can you let me know what's the
discrepancy you are referring to?
> Change master to always update registry before in-memory state
> --------------------------------------------------------------
>
> Key: MESOS-6090
> URL: https://issues.apache.org/jira/browse/MESOS-6090
> Project: Mesos
> Issue Type: Improvement
> Components: master
> Reporter: Neil Conway
> Assignee: Neil Conway
> Labels: mesosphere
>
> When a new slave attempts to register, the registry is updated first, then
> the master's in-memory state is updated if the registry operation is applied
> successfully. However, when a slave is removed or reregisters, the master
> first updates its in-memory state, then updates the registry. This has two
> problems:
> 1. It makes it harder to reason about the correctness of concurrent
> operations that read in-memory state and update the registry.
> 2. It can leak incorrect information via the HTTP endpoints. That is, if we
> update the master's in-memory state on removal or reregistration, that change
> will be observable via the HTTP endpoints. If the master then fails over (and
> the registry operation fails), the information returned via the endpoint will
> be incorrect. The master has special code to avoid this inaccuracy for
> reconciliation (see {{Master::transitioning()}}), but not for the endpoints.
> I think it is simpler to just always update the registry first.
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