[jira] [Commented] (IGNITE-4157) Use discovery custom messages instead of marshaller cache

["Sergey Chugunov (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/IGNITE-4157?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15711292#comment-15711292 ] 

Sergey Chugunov commented on IGNITE-4157:
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Marshaller mapping exchange was rewritten to work synchronously: when some node wants to add new mapping it gets blocked until grid accepts the mapping or rejects it.

> Use discovery custom messages instead of marshaller cache
> ---------------------------------------------------------
>
>                 Key: IGNITE-4157
>                 URL: https://issues.apache.org/jira/browse/IGNITE-4157
>             Project: Ignite
>          Issue Type: Improvement
>          Components: cache
>            Reporter: Alexey Goncharuk
>            Assignee: Sergey Chugunov
>             Fix For: 2.0
>
>
> Currently we use system caches for keeping classname to class ID mapping and for storing binary metadata
> This has several serious disadvantages:
> 1) We need to introduce at least two additional thread pools for each of these caches
> 2) Since cache operations require stable topology, registering a class ID or updating metadata inside a transaction or another cache operation is tricky and deadlock-prone.
> 3) It may be beneficial in some cases to have nodes with no caches at all, currently this is impossible because system caches are always present.
> 4) Reading binary metadata leads to huge local contention, caching metadata values in a local map doubles memory consumption
> I suggest we use discovery custom events for these purposes. Each node will have a corresponding local map (state) which will be updated inside custom event handler. From the first point of view, this should remove all the disadvantages above.



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