[jira] [Commented] (DAFFODIL-1444) Performance - schema compilation

["Michael Beckerle (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/DAFFODIL-1444?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16767701#comment-16767701 ] 

Michael Beckerle commented on DAFFODIL-1444:
--------------------------------------------

See page: [https://cwiki.apache.org/confluence/pages/viewpage.action?pageId=103090465]

Discusses the areas where change is needed to really fix this issue.

> Performance - schema compilation
> --------------------------------
>
>                 Key: DAFFODIL-1444
>                 URL: https://issues.apache.org/jira/browse/DAFFODIL-1444
>             Project: Daffodil
>          Issue Type: Improvement
>          Components: Front End, Middle "End", Performance
>            Reporter: Michael Beckerle
>            Assignee: Steve Lawrence
>            Priority: Major
>             Fix For: 2.4.0
>
>
> Large DFDL schemas are very slow to compile.
> We could focus on speeding this up, and should get some low-hanging fruit here.
> But ultimately, a really large DFDL schema needs to be compiled in pieces. (DEBATABLE - focus should FIRST be on speeding up and reducing the massive copying that goes on. Separate compilation is a harder issue that we can defer.)
> This means we need to be able to reload a compiled schema just to restore it's parsers/unparsers and associated runtime data structures to memory so that another schema that depends on it can then be compiled. 
> DFDL schema compilation needs to be understood in order to decompose a schema into separately compilable units. THere's no point in trying to compile a schema layer by layer - a DFDL schema containing all type definitions, for example, doesn't compile to anything. There have to be top level elements in order for DFDL schema compilation to do anything.
> So given a large data format with many top-level element types, we need the compiler to recognize element references to pre-compiled top-level elements, and avoid recompiling new instances of them if the surrounding environment is the same. That is, surrounding default format specification is the same.



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