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From "Barry Jones (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (AVRO-1642) JVM Spec Violation 255 Parameter Limit Exceeded
Date Tue, 05 Apr 2016 19:27:25 GMT

    [ https://issues.apache.org/jira/browse/AVRO-1642?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15226966#comment-15226966

Barry Jones commented on AVRO-1642:

Sure. From having a read through the code review comments I should be able to make most of
the changes (with zero experience of this codebase), but please can you give me some pointers

* "add an input validation that the schema is a Record, add a failure test for same" - where
can I find examples of what is requested here?
* "Types that need a java long or double count as 2, everything else is 1. Important to note
that it's only the primitive types long and double" - what does this mean? Does it require
code changes or is it just an explanatory note with no code changes required?


> JVM Spec Violation 255 Parameter Limit Exceeded 
> ------------------------------------------------
>                 Key: AVRO-1642
>                 URL: https://issues.apache.org/jira/browse/AVRO-1642
>             Project: Avro
>          Issue Type: Bug
>          Components: java
>    Affects Versions: 1.7.7
>         Environment: Windows/Linux all Java
>            Reporter: Bryce Alcock
>            Assignee: Prateek Rungta
>            Priority: Critical
>              Labels: build, maven, specific
>         Attachments: AVRO-1642-0.patch, AVRO-1642-1.patch, avro-1642-fail.tar
> The JVM Spec indicates that:
> {quote}The number of method parameters is limited to 255 by the definition of a method
descriptor (ยง4.3.3), where the limit includes one unit for this in the case of instance or
interface method invocations. Note that a method descriptor is defined in terms of a notion
of method parameter length in which a parameter of type long or double contributes two units
to the length, so parameters of these types further reduce the limit. {quote}
> Avro Generated Java code with say more than 255 fields will create a constructor that
is not valid and won't compile.
> Simple test is to create a 256 field avro schema, use the avro-maven auto code gen plugin,
and try to compile the resulting class.
> DON'T use linux when doing this use windows, my suspicion is that Linux JavaC generates
invalid byte code but does not complain.
> Windows will correctly complain indicating that you are a violator of the JVM specification.

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