[jira] [Resolved] (UIMA-2772) DUCC resource manager - Restart and fast-start

["Jim Challenger (JIRA)" <de...@uima.apache.org>]

     [ https://issues.apache.org/jira/browse/UIMA-2772?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Jim Challenger resolved UIMA-2772.
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    Resolution: Fixed
    
> DUCC resource manager - Restart and fast-start
> ----------------------------------------------
>
>                 Key: UIMA-2772
>                 URL: https://issues.apache.org/jira/browse/UIMA-2772
>             Project: UIMA
>          Issue Type: Bug
>          Components: DUCC
>            Reporter: Jim Challenger
>            Assignee: Jim Challenger
>
> Currently RM waits a "reasonable time" (init-stabiity) on startup to allow nodes to check in, before accepting scheduling requests.  It is not possible to know exactly how long to wait, making init-stability a heuristic.  For normal startup this is not a problem.  If RM is restarting 'hot', or if the orchestrator publishes non-preemptable jobs on restart, and the necessary nodes have not arrived by the completion of init-stability wait, this can cause many problems: over-commitment, under-commitment, and in some cases  inconsistent state (and crashes).
> To remedy this, RM will include the full Node object in its publications to the OR, which will echo them back for work that it believes to be active. On startup RM can fully reconstruct state as of its last publication from this, eliminating the problem. A side-effect of this is that RM need not wait for nodes to check in, significantly decreasing its startup time.  If nodes added to the resource pool in this way never check in, the normal "dead node" mechanism will kick in, maintaining consistency.

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