+1 to what Claire is proposing. Would be nice to have this merged to avoid 
fixing things on our side!

On 2021/08/02 14:58:11, Claire McGinty <[email protected]> wrote: 
> hi, I wanted to ping this thread again! It would be really helpful to know
> whether this is something that can be eventually fixed in Beam, or whether
> we'll have to make the changes on our end.
> 
> - Claire
> 
> On Tue, Jul 27, 2021 at 8:06 AM Claire McGinty <[email protected]>
> wrote:
> 
> > Right; since ReflectData has just the one instance per classloader using
> > it in the API is purely stylistic to match the other signatures taking in
> > Class<T>/Schema :) open to any changes, the Boolean flag option is probably
> > clearer I can do whichever option is most in line with Beam style!
> >
> > -Claire
> >
> > On Tue, Jul 27, 2021 at 5:47 AM Ryan Skraba <[email protected]> wrote:
> >
> >> Hello!  I took a quick look -- I think there's some potential
> >> confusion on this line[1] and the reflectData argument being passed
> >> into the new constructor.
> >>
> >> If I'm reading correctly, the argument passed in is never actually
> >> used in the eventual ReflectDatumReader/Writer, and it's a different
> >> type than the "this.reflectData" member in the instance.
> >>
> >> To restore the original behaviour, I'd probably recommend just passing
> >> in a boolean argument instead, something very explicit along the lines
> >> of "useReflectionOnSpecificData", or "alwaysUseAvroReflect".  That's
> >> also the reason to consider a very simple AvroReflectCoder.of(...)
> >> instead of an AvroCoder.of(x, y, true) factory method for readability,
> >> like what was done with AvroGenericCoder.
> >>
> >> It would be easier to comment on a PR, don't hesitate!
> >>
> >> All my best, Ryan
> >>
> >> [1]
> >> https://github.com/apache/beam/compare/master...clairemcginty:avro_reflect_coder_option?expand=1#diff-e875a9933286d97dd3d3d21a61e6f11c0e35624e97411c1b98f1ac672c21045dR311
> >>
> >>
> >> On Mon, Jul 26, 2021 at 6:42 PM Claire McGinty
> >> <[email protected]> wrote:
> >> >
> >> > Thanks! I put up a branch with a possible solution for adding the
> >> Reflect option to AvroCoder with as minimal a code change as possible [1] -
> >> would love to get anyone's thoughts on this.
> >> >
> >> > - Claire
> >> >
> >> > On Wed, Jul 21, 2021 at 7:00 PM Ahmet Altay <[email protected]> wrote:
> >> >>
> >> >>
> >> >>
> >> >> On Wed, Jul 21, 2021 at 9:37 AM Claire McGinty <
> >> [email protected]> wrote:
> >> >>>
> >> >>> Hi Ahmet! Yes, I think it should be documented in the release notes.
> >> >>
> >> >>
> >> >> Great. +Vitaly, do you want to add the breaking change to the release
> >> notes, since this was related your change.
> >> >>
> >> >>>
> >> >>> What do you think of Ryan’s suggestion to add a ReflectAvroCoder or a
> >> configuration option to the existing AvroCoder?
> >> >>
> >> >>
> >> >> I am not sure I am the best person to answer this. Second option, of
> >> adding a configuration to the existing AvroCoder, rather than creating a
> >> new coder makes more sense to me.
> >> >>
> >> >> That said, people who might have an opinion: /cc @Ismaël Mejía
> >> @Kenneth Knowles @Lukasz Cwik +Vitaly
> >> >>
> >> >>>
> >> >>>
> >> >>> Thanks,
> >> >>> Claire
> >> >>>
> >> >>> On Tue, Jul 20, 2021 at 4:15 PM Ahmet Altay <[email protected]> wrote:
> >> >>>>
> >> >>>> Is this something we need to add to the 2.30.0 release notes (
> >> https://beam.apache.org/blog/beam-2.30.0/) as a breaking change?
> >> >>>>
> >> >>>> On Fri, Jul 16, 2021 at 7:11 AM Ryan Skraba <[email protected]> wrote:
> >> >>>>>
> >> >>>>> Hello!  Good catch, I'm taking a look, but it looks like you're
> >> >>>>> entirely correct and there isn't any obvious workaround.  I guess
> >> you
> >> >>>>> could regenerate every SpecificRecord class in order to add the
> >> >>>>> "java-class" or "avro.java.string" annotation, but that shouldn't be
> >> >>>>> necessary.
> >> >>>>>
> >> >>>>> From the Avro perspective, we should always have been using
> >> >>>>> SpecificDatumReader/Writer for all generated SpecificRecords...  We
> >> >>>>> would still have the same Utf8 and .toString problems, but at least
> >> >>>>> there would be no change in behaviour during migration :/
> >> >>>>>
> >> >>>>> As a side note, the Apache Avro project should probably reconsider
> >> >>>>> whether the Utf8 class still adds any value with modern JVMs!  If I
> >> >>>>> understand correctly, it was originally in place because Hadoop had
> >> a
> >> >>>>> performance boost when it could reuse mutable data containers.
> >> >>>>>
> >> >>>>> Moving forward, I think your suggestion is the most pragmatic:
> >> either
> >> >>>>> add a configuration option to AvroCoder to always drop to
> >> ReflectData,
> >> >>>>> or explicitly provide a ReflectAvroCoder that only uses reflection.
> >> >>>>>
> >> >>>>> I took the liberty of creating the JIRA
> >> >>>>> https://issues.apache.org/jira/browse/BEAM-12628 JIRA, so I could
> >> >>>>> create an link an Avro issue!  Please feel free to update if I
> >> missed
> >> >>>>> anything.
> >> >>>>>
> >> >>>>> Best regards, Ryan
> >> >>>>>
> >> >>>>> On Thu, Jul 15, 2021 at 10:53 PM Claire McGinty
> >> >>>>> <[email protected]> wrote:
> >> >>>>> >
> >> >>>>> > Hi all,
> >> >>>>> >
> >> >>>>> > When upgrading from Beam 2.29.0 to 2.30.0, we encountered some
> >> unexpected runtime issues due to changes from BEAM-2303. This PR updated
> >> AvroCoder to use SpecificDatum{Reader,Writer} instead
> >> ofReflectDatum{Reader,Writer} in its implementation.
> >> >>>>> >
> >> >>>>> > When using the Reflect* suite, Avro string fields have
> >> getters/setters defined with a CharSequence signature, but are by default
> >> decoded as java.lang.Strings [1]. But the Specific* suitehas a different
> >> default behavior for decoding Avro string fields: unless the Avro schema
> >> property "java-class" is set to "java.lang.String", the decoded
> >> CharSequences will by default be implemented as org.apache.avro.util.Utf8
> >> objects [2].
> >> >>>>> >
> >> >>>>> > This is causing some migration pain for us as we're having to
> >> either add the java-class property to all string field schemas, or call
> >> .toString on a lot of fields we could just cast before. Additionally, Utf8
> >> isn't Serializable and there's no default Coder representation for it.
> >> Beam's AvroSink/AvroSource still use the Reflect* reader/writer, as well.I
> >> created a quick Gist to demonstrate the issue: [3].
> >> >>>>> >
> >> >>>>> > I'm wondering if there's any possibility of making the use of
> >> Reflect* vs Specific* configurable in AvroCoder, or maybe setting a default
> >> String type in the coder constructor.  If not, maybe this change should be
> >> documented in the release notes?
> >> >>>>> >
> >> >>>>> > Thanks,
> >> >>>>> > Claire
> >>
> >
> 

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