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https://issues.apache.org/jira/browse/UIMA-5662?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16283707#comment-16283707
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Marshall Schor commented on UIMA-5662:
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I'm thinking about an alterantive approach. Another Jira ( UIMA_5664) adds a
semi-built-in new type, a map from int -> FS. Another approach to
deserialization could be:
1) change most deserializers to set the fsId to the v2-fs-id value imputed from
the serialized form, either explicitly or implicitly.
* This allows a subsequent serialization to reuse these, keeping them
more-or-less stable.
* This would be independent of supporting low-level-access, remembering the
fs-id -> fs relation in a map, etc.
2) Allow users calling deserializers to specify a map from int -> FS (map of
their choice, for instance a HashMap or LinkedHashMap). If such a parameter is
provided, the deserializers would add all the deserialized FSs to the map, with
key being the v2-fs-id.
3) The deserializers would **not** add the FSs to the internal hidden map that
makes low-level-cas-API to get FSFromRef work.
The pluses and minuses of this seem to be:
* 3a) minus: low level cas Access doesn't work. Code using this needs to be
upgraded.
* 3b) plus: the internal low-level cas Access map not being used, allows future
garbage collection.
* 3c) plus: users have more explicit control of what stays in the map. Things
not in the map could be GCd. Depending on their use case, they could
** clear the map after use
** remove selected entries
* 3c) Going forward, they could convert their application to save the map in
the cas (using the new semi-built-in type); they could support multiple maps,
etc.
Does this sound like a good general direction? Other thoughts?
> uv3 support CAS deserialization subsequent low level access
> -----------------------------------------------------------
>
> Key: UIMA-5662
> URL: https://issues.apache.org/jira/browse/UIMA-5662
> Project: UIMA
> Issue Type: Improvement
> Components: Core Java Framework
> Affects Versions: 3.0.0SDK-beta
> Reporter: Marshall Schor
> Assignee: Marshall Schor
> Priority: Minor
> Fix For: 3.0.0SDK
>
>
> Some users depend 1) constant v2-ids for FSs preserved in deserialization and
> serialization, and 2) low level cas API access to these.
> V3 normally doesn't maintain tables linking ids to FSs, as these (unless weak
> refs are used) prevent GC of unreachable FSs.
> Based on a mode, set by -Duima.deserialize_perserve_ids, and also
> controllable by new config option per deserialize call, alter the
> deserialization for those deserializers which know about v2 ids, to put these
> into the map used for low-level CAS access, using the actual v2 ids, and
> change the v3 next available id for future new FSs to be 1 beyond the end.
> The -Duima.deserialize-preserve_ids global setting is needed to handle the
> use case of some annotators using low-level APIs, when part of a pipeline is
> "remoted".
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