Re: Implementing zero-dim and zero-size tensors in MXNet and its impact on your codebases

2019-04-11 Thread Jun Wu
Thank all for the discussion. To make this PR unblocked by the discussion
of semver concerns, I made copies of the APIs I need to change and worked
on those copies. Thanks to Tong, Yizhi, and Sergey who updated all the
language bindings to use the new C APIs supporting zero-dim/size tensors,
this PR currently is free of SemVer concerns on either C APIs and any
language bindings.

Nevertheless, I think it's the time for us to ponder the necessity of
keeping all C APIs under the umbrella of semver. As Marco pointed out,
treating C APIs as user-facing APIs brings in the risk of diverging
frontend functionality as well as considerably increases the complexity of
development. We can conduct a survey among MXNet users by collecting the C
APIs they directly interact with and keep those under semver.

Thank all again for sharing the thoughts. We will keeping rolling out NumPy
compatible features after this PR and look forward to helping MXNet users
migrate to using NumPy features.

On Thu, Apr 11, 2019 at 12:32 PM Anirudh Subramanian 
wrote:

> Hi Marco,
>
> The backend private APIs in engine, executor, storage, ndarray etc. can
> still be changed.
> I understand that it may introduce code duplication, but introducing
> duplicate C APIs can still be better than the backend
> developer having to worry about different frontends. Not to mention a
> frontend which is not yet merged to the
> repo but in its own repo, these repos should also be considered consumers
> of MXNet API.
>
> Anirudh
>
> On Thu, Apr 11, 2019 at 12:12 PM Marco de Abreu 
> wrote:
>
> > Good point about the adoption speed for the different frontends, Anirudh.
> > While this is a quite valid argument, I'm afraid of the complexity it
> might
> > introduce as well as a risk of further diverging frontend functionality.
> >
> > I'd rather propose that we introduce a guideline to follow when changes
> to
> > C-APIs are being made. Part of that could be starting a thread like this
> > one that lays down the changes that are being made to the C-API. We could
> > then coordinate the changes to the different frontends and gather people
> > from the community who feel comfortable to do the changes in the
> respective
> > frontends. If nobody speaks up, the original proposer of that change
> could
> > be responsible to do the necessary changes.
> >
> > An adjacent topic for this discussion could be test coverage: We
> currently
> > have no tools to determine which frontend hits which C-API and where
> > changes have to be made. This might be a topic we should spark up again
> > separately.
> >
> > -Marco
> >
> > On Thu, Apr 11, 2019 at 8:55 PM Marco de Abreu 
> > wrote:
> >
> > > My personal opinion towards that discussion is that we should keep the
> > > C-API free from semantic versioning because otherwise we're introducing
> > two
> > > "fronts" that we have to maintain backwards compatibility for. By the
> > way,
> > > currently, we have no way to verify and guarantee the compatibility of
> > the
> > > C-API. The major issue I'd see with adding SemVer for the C-API is that
> > > this would increase the complexity of changes that are (in my opinion)
> > > entirely internal to MXNet by introducing another thing that developers
> > > would have to look out for - possibly introducing code duplication as
> > > described by Jun while not providing any clear benefits to me.
> > >
> > > If there is a use-case where people can not even use our C++ package,
> > then
> > > we could have discussions about introducing a user-facing C-API, but
> > right
> > > now this approach to interface with our C-API (although I know that
> > people
> > > use it) seem a bit like using undocumented Windows APIs: They work, but
> > > it's on your own risk, they might always break and there's no
> guarantee.
> > >
> > > -Marco
> > >
> > > On Thu, Apr 11, 2019 at 8:52 PM Anirudh Subramanian <
> > anirudh2...@gmail.com>
> > > wrote:
> > >
> > >> Hi Jun,
> > >>
> > >> Till now from what I have observed this has been an undocumented
> > guideline
> > >> to not break C APIs (example:
> > >>
> >
> https://github.com/apache/incubator-mxnet/pull/11429#discussion_r199564999
> > >> ).
> > >> Although the C APIs are supposed to serve only as bridges for frontend
> > >> language bindings (exception being C Predict API), I think there are
> 3rd
> > >> party libraries like Horovod which are starting to
> > >> depend on it (https://github.com/apache/incubator-mxnet/pull/14615) .
> > >>
> > >> Also, since MXNet has a lot of frontend bindings ensuring backward
> > >> compatibility with semver can help frontend bindings adopt the new
> APIs
> > at
> > >> their own pace.
> > >>
> > >> Anirudh
> > >>
> > >>
> > >> On Thu, Apr 11, 2019 at 10:58 AM Jun Wu  wrote:
> > >>
> > >> > I'm not sure about whether C APIs should fall under semver. This is
> > the
> > >> > discussion we would like to have with the community.
> > >> >
> > >> > My thinking on this:
> > >> > 1. In most of the cases, C APIs only serve 

Re: Implementing zero-dim and zero-size tensors in MXNet and its impact on your codebases

2019-04-11 Thread Anirudh Subramanian
Hi Marco,

The backend private APIs in engine, executor, storage, ndarray etc. can
still be changed.
I understand that it may introduce code duplication, but introducing
duplicate C APIs can still be better than the backend
developer having to worry about different frontends. Not to mention a
frontend which is not yet merged to the
repo but in its own repo, these repos should also be considered consumers
of MXNet API.

Anirudh

On Thu, Apr 11, 2019 at 12:12 PM Marco de Abreu 
wrote:

> Good point about the adoption speed for the different frontends, Anirudh.
> While this is a quite valid argument, I'm afraid of the complexity it might
> introduce as well as a risk of further diverging frontend functionality.
>
> I'd rather propose that we introduce a guideline to follow when changes to
> C-APIs are being made. Part of that could be starting a thread like this
> one that lays down the changes that are being made to the C-API. We could
> then coordinate the changes to the different frontends and gather people
> from the community who feel comfortable to do the changes in the respective
> frontends. If nobody speaks up, the original proposer of that change could
> be responsible to do the necessary changes.
>
> An adjacent topic for this discussion could be test coverage: We currently
> have no tools to determine which frontend hits which C-API and where
> changes have to be made. This might be a topic we should spark up again
> separately.
>
> -Marco
>
> On Thu, Apr 11, 2019 at 8:55 PM Marco de Abreu 
> wrote:
>
> > My personal opinion towards that discussion is that we should keep the
> > C-API free from semantic versioning because otherwise we're introducing
> two
> > "fronts" that we have to maintain backwards compatibility for. By the
> way,
> > currently, we have no way to verify and guarantee the compatibility of
> the
> > C-API. The major issue I'd see with adding SemVer for the C-API is that
> > this would increase the complexity of changes that are (in my opinion)
> > entirely internal to MXNet by introducing another thing that developers
> > would have to look out for - possibly introducing code duplication as
> > described by Jun while not providing any clear benefits to me.
> >
> > If there is a use-case where people can not even use our C++ package,
> then
> > we could have discussions about introducing a user-facing C-API, but
> right
> > now this approach to interface with our C-API (although I know that
> people
> > use it) seem a bit like using undocumented Windows APIs: They work, but
> > it's on your own risk, they might always break and there's no guarantee.
> >
> > -Marco
> >
> > On Thu, Apr 11, 2019 at 8:52 PM Anirudh Subramanian <
> anirudh2...@gmail.com>
> > wrote:
> >
> >> Hi Jun,
> >>
> >> Till now from what I have observed this has been an undocumented
> guideline
> >> to not break C APIs (example:
> >>
> https://github.com/apache/incubator-mxnet/pull/11429#discussion_r199564999
> >> ).
> >> Although the C APIs are supposed to serve only as bridges for frontend
> >> language bindings (exception being C Predict API), I think there are 3rd
> >> party libraries like Horovod which are starting to
> >> depend on it (https://github.com/apache/incubator-mxnet/pull/14615) .
> >>
> >> Also, since MXNet has a lot of frontend bindings ensuring backward
> >> compatibility with semver can help frontend bindings adopt the new APIs
> at
> >> their own pace.
> >>
> >> Anirudh
> >>
> >>
> >> On Thu, Apr 11, 2019 at 10:58 AM Jun Wu  wrote:
> >>
> >> > I'm not sure about whether C APIs should fall under semver. This is
> the
> >> > discussion we would like to have with the community.
> >> >
> >> > My thinking on this:
> >> > 1. In most of the cases, C APIs only serve as bridges between frontend
> >> > language bindings and C++ backend. Most of users/developers do not
> >> interact
> >> > directly with C APIs.
> >> > 2. The cases I can think of where C APIs are directly adopted in
> >> > application development are model deployment in a C/C++ environment.
> In
> >> > those cases, developers only interact with C Predict APIs, which we
> >> didn't
> >> > touch.
> >> >
> >> > If the community feel that we are obliged to keep the semver for all C
> >> > APIs, we can try to make a copy of the C APIs we intend to modify in
> >> the PR
> >> > and keep the old signatures intact, this will introduce a lot of
> >> duplicate
> >> > code though.
> >> >
> >> > On Thu, Apr 11, 2019 at 8:50 AM Anirudh Subramanian <
> >> anirudh2...@gmail.com
> >> > >
> >> > wrote:
> >> >
> >> > > I was under the impression that C API does fall under semver. Has
> this
> >> > been
> >> > > discussed somewhere before ? Is this also the case for C Predict
> API ?
> >> > >
> >> > > On Thu, Apr 11, 2019, 8:08 AM Marco de Abreu <
> marco.g.ab...@gmail.com
> >> >
> >> > > wrote:
> >> > >
> >> > > > In case only changes to the c-api are being made, it doesn't fall
> >> under
> >> > > our
> >> > > > semantic versioning since that's not a 

Re: Implementing zero-dim and zero-size tensors in MXNet and its impact on your codebases

2019-04-11 Thread Marco de Abreu
Good point about the adoption speed for the different frontends, Anirudh.
While this is a quite valid argument, I'm afraid of the complexity it might
introduce as well as a risk of further diverging frontend functionality.

I'd rather propose that we introduce a guideline to follow when changes to
C-APIs are being made. Part of that could be starting a thread like this
one that lays down the changes that are being made to the C-API. We could
then coordinate the changes to the different frontends and gather people
from the community who feel comfortable to do the changes in the respective
frontends. If nobody speaks up, the original proposer of that change could
be responsible to do the necessary changes.

An adjacent topic for this discussion could be test coverage: We currently
have no tools to determine which frontend hits which C-API and where
changes have to be made. This might be a topic we should spark up again
separately.

-Marco

On Thu, Apr 11, 2019 at 8:55 PM Marco de Abreu 
wrote:

> My personal opinion towards that discussion is that we should keep the
> C-API free from semantic versioning because otherwise we're introducing two
> "fronts" that we have to maintain backwards compatibility for. By the way,
> currently, we have no way to verify and guarantee the compatibility of the
> C-API. The major issue I'd see with adding SemVer for the C-API is that
> this would increase the complexity of changes that are (in my opinion)
> entirely internal to MXNet by introducing another thing that developers
> would have to look out for - possibly introducing code duplication as
> described by Jun while not providing any clear benefits to me.
>
> If there is a use-case where people can not even use our C++ package, then
> we could have discussions about introducing a user-facing C-API, but right
> now this approach to interface with our C-API (although I know that people
> use it) seem a bit like using undocumented Windows APIs: They work, but
> it's on your own risk, they might always break and there's no guarantee.
>
> -Marco
>
> On Thu, Apr 11, 2019 at 8:52 PM Anirudh Subramanian 
> wrote:
>
>> Hi Jun,
>>
>> Till now from what I have observed this has been an undocumented guideline
>> to not break C APIs (example:
>> https://github.com/apache/incubator-mxnet/pull/11429#discussion_r199564999
>> ).
>> Although the C APIs are supposed to serve only as bridges for frontend
>> language bindings (exception being C Predict API), I think there are 3rd
>> party libraries like Horovod which are starting to
>> depend on it (https://github.com/apache/incubator-mxnet/pull/14615) .
>>
>> Also, since MXNet has a lot of frontend bindings ensuring backward
>> compatibility with semver can help frontend bindings adopt the new APIs at
>> their own pace.
>>
>> Anirudh
>>
>>
>> On Thu, Apr 11, 2019 at 10:58 AM Jun Wu  wrote:
>>
>> > I'm not sure about whether C APIs should fall under semver. This is the
>> > discussion we would like to have with the community.
>> >
>> > My thinking on this:
>> > 1. In most of the cases, C APIs only serve as bridges between frontend
>> > language bindings and C++ backend. Most of users/developers do not
>> interact
>> > directly with C APIs.
>> > 2. The cases I can think of where C APIs are directly adopted in
>> > application development are model deployment in a C/C++ environment. In
>> > those cases, developers only interact with C Predict APIs, which we
>> didn't
>> > touch.
>> >
>> > If the community feel that we are obliged to keep the semver for all C
>> > APIs, we can try to make a copy of the C APIs we intend to modify in
>> the PR
>> > and keep the old signatures intact, this will introduce a lot of
>> duplicate
>> > code though.
>> >
>> > On Thu, Apr 11, 2019 at 8:50 AM Anirudh Subramanian <
>> anirudh2...@gmail.com
>> > >
>> > wrote:
>> >
>> > > I was under the impression that C API does fall under semver. Has this
>> > been
>> > > discussed somewhere before ? Is this also the case for C Predict API ?
>> > >
>> > > On Thu, Apr 11, 2019, 8:08 AM Marco de Abreu > >
>> > > wrote:
>> > >
>> > > > In case only changes to the c-api are being made, it doesn't fall
>> under
>> > > our
>> > > > semantic versioning since that's not a user facing API and thus I'd
>> be
>> > in
>> > > > favour as doing it as part of a minor release. If there is any
>> > > behavioural
>> > > > change from a user perspective (a good indicator would be if tests
>> have
>> > > to
>> > > > be changed as reaction to the Backend changes), then I'd prefer a
>> major
>> > > > release.
>> > > >
>> > > > I'd slightly prefer a minor release since this change touches quite
>> a
>> > few
>> > > > parts and could risk being outdated/diverged as the time until 2.0
>> > > > progresses.
>> > > >
>> > > > -Marco
>> > > >
>> > > > Aaron Markham  schrieb am Do., 11. Apr.
>> > 2019,
>> > > > 16:28:
>> > > >
>> > > > > Just curious about when this kind of change will land. Would it
>> wait
>> > > for
>> > > > > 2.0 or would it be 

Re: Implementing zero-dim and zero-size tensors in MXNet and its impact on your codebases

2019-04-11 Thread Marco de Abreu
My personal opinion towards that discussion is that we should keep the
C-API free from semantic versioning because otherwise we're introducing two
"fronts" that we have to maintain backwards compatibility for. By the way,
currently, we have no way to verify and guarantee the compatibility of the
C-API. The major issue I'd see with adding SemVer for the C-API is that
this would increase the complexity of changes that are (in my opinion)
entirely internal to MXNet by introducing another thing that developers
would have to look out for - possibly introducing code duplication as
described by Jun while not providing any clear benefits to me.

If there is a use-case where people can not even use our C++ package, then
we could have discussions about introducing a user-facing C-API, but right
now this approach to interface with our C-API (although I know that people
use it) seem a bit like using undocumented Windows APIs: They work, but
it's on your own risk, they might always break and there's no guarantee.

-Marco

On Thu, Apr 11, 2019 at 8:52 PM Anirudh Subramanian 
wrote:

> Hi Jun,
>
> Till now from what I have observed this has been an undocumented guideline
> to not break C APIs (example:
> https://github.com/apache/incubator-mxnet/pull/11429#discussion_r199564999
> ).
> Although the C APIs are supposed to serve only as bridges for frontend
> language bindings (exception being C Predict API), I think there are 3rd
> party libraries like Horovod which are starting to
> depend on it (https://github.com/apache/incubator-mxnet/pull/14615) .
>
> Also, since MXNet has a lot of frontend bindings ensuring backward
> compatibility with semver can help frontend bindings adopt the new APIs at
> their own pace.
>
> Anirudh
>
>
> On Thu, Apr 11, 2019 at 10:58 AM Jun Wu  wrote:
>
> > I'm not sure about whether C APIs should fall under semver. This is the
> > discussion we would like to have with the community.
> >
> > My thinking on this:
> > 1. In most of the cases, C APIs only serve as bridges between frontend
> > language bindings and C++ backend. Most of users/developers do not
> interact
> > directly with C APIs.
> > 2. The cases I can think of where C APIs are directly adopted in
> > application development are model deployment in a C/C++ environment. In
> > those cases, developers only interact with C Predict APIs, which we
> didn't
> > touch.
> >
> > If the community feel that we are obliged to keep the semver for all C
> > APIs, we can try to make a copy of the C APIs we intend to modify in the
> PR
> > and keep the old signatures intact, this will introduce a lot of
> duplicate
> > code though.
> >
> > On Thu, Apr 11, 2019 at 8:50 AM Anirudh Subramanian <
> anirudh2...@gmail.com
> > >
> > wrote:
> >
> > > I was under the impression that C API does fall under semver. Has this
> > been
> > > discussed somewhere before ? Is this also the case for C Predict API ?
> > >
> > > On Thu, Apr 11, 2019, 8:08 AM Marco de Abreu 
> > > wrote:
> > >
> > > > In case only changes to the c-api are being made, it doesn't fall
> under
> > > our
> > > > semantic versioning since that's not a user facing API and thus I'd
> be
> > in
> > > > favour as doing it as part of a minor release. If there is any
> > > behavioural
> > > > change from a user perspective (a good indicator would be if tests
> have
> > > to
> > > > be changed as reaction to the Backend changes), then I'd prefer a
> major
> > > > release.
> > > >
> > > > I'd slightly prefer a minor release since this change touches quite a
> > few
> > > > parts and could risk being outdated/diverged as the time until 2.0
> > > > progresses.
> > > >
> > > > -Marco
> > > >
> > > > Aaron Markham  schrieb am Do., 11. Apr.
> > 2019,
> > > > 16:28:
> > > >
> > > > > Just curious about when this kind of change will land. Would it
> wait
> > > for
> > > > > 2.0 or would it be in 1.5 or another minor release?
> > > > >
> > > > > On Thu, Apr 11, 2019, 00:15 Junru Shao 
> > > wrote:
> > > > >
> > > > > > Really nice improvement over MXNet's usability! I suggest that we
> > > could
> > > > > > make numpy-compatible behavior default in 2.0.
> > > > > >
> > > > > > On Wed, Apr 10, 2019 at 11:34 PM Jun Wu 
> > wrote:
> > > > > >
> > > > > > > Dear Community,
> > > > > > >
> > > > > > > A while ago, we sent out an RFC
> > > > > > > 
> > > discussing
> > > > > the
> > > > > > > initiative introducing NumPy compatibility into MXNet. As the
> > first
> > > > > > outcome
> > > > > > > of this initiative, we submitted the PR
> > > > > > > 
> providing
> > > the
> > > > > > > infrastructure of supporting zero-dim (scalar) and zero-size
> > > tensors,
> > > > > > which
> > > > > > > have been long-missing in MXNet.
> > > > > > >
> > > > > > > In our implementation, we have put the best efforts of keeping
> > the
> > > > > > promise
> > > > > > > of backward compatibility in all the language 

Re: Implementing zero-dim and zero-size tensors in MXNet and its impact on your codebases

2019-04-11 Thread Anirudh Subramanian
Hi Jun,

Till now from what I have observed this has been an undocumented guideline
to not break C APIs (example:
https://github.com/apache/incubator-mxnet/pull/11429#discussion_r199564999).
Although the C APIs are supposed to serve only as bridges for frontend
language bindings (exception being C Predict API), I think there are 3rd
party libraries like Horovod which are starting to
depend on it (https://github.com/apache/incubator-mxnet/pull/14615) .

Also, since MXNet has a lot of frontend bindings ensuring backward
compatibility with semver can help frontend bindings adopt the new APIs at
their own pace.

Anirudh


On Thu, Apr 11, 2019 at 10:58 AM Jun Wu  wrote:

> I'm not sure about whether C APIs should fall under semver. This is the
> discussion we would like to have with the community.
>
> My thinking on this:
> 1. In most of the cases, C APIs only serve as bridges between frontend
> language bindings and C++ backend. Most of users/developers do not interact
> directly with C APIs.
> 2. The cases I can think of where C APIs are directly adopted in
> application development are model deployment in a C/C++ environment. In
> those cases, developers only interact with C Predict APIs, which we didn't
> touch.
>
> If the community feel that we are obliged to keep the semver for all C
> APIs, we can try to make a copy of the C APIs we intend to modify in the PR
> and keep the old signatures intact, this will introduce a lot of duplicate
> code though.
>
> On Thu, Apr 11, 2019 at 8:50 AM Anirudh Subramanian  >
> wrote:
>
> > I was under the impression that C API does fall under semver. Has this
> been
> > discussed somewhere before ? Is this also the case for C Predict API ?
> >
> > On Thu, Apr 11, 2019, 8:08 AM Marco de Abreu 
> > wrote:
> >
> > > In case only changes to the c-api are being made, it doesn't fall under
> > our
> > > semantic versioning since that's not a user facing API and thus I'd be
> in
> > > favour as doing it as part of a minor release. If there is any
> > behavioural
> > > change from a user perspective (a good indicator would be if tests have
> > to
> > > be changed as reaction to the Backend changes), then I'd prefer a major
> > > release.
> > >
> > > I'd slightly prefer a minor release since this change touches quite a
> few
> > > parts and could risk being outdated/diverged as the time until 2.0
> > > progresses.
> > >
> > > -Marco
> > >
> > > Aaron Markham  schrieb am Do., 11. Apr.
> 2019,
> > > 16:28:
> > >
> > > > Just curious about when this kind of change will land. Would it wait
> > for
> > > > 2.0 or would it be in 1.5 or another minor release?
> > > >
> > > > On Thu, Apr 11, 2019, 00:15 Junru Shao 
> > wrote:
> > > >
> > > > > Really nice improvement over MXNet's usability! I suggest that we
> > could
> > > > > make numpy-compatible behavior default in 2.0.
> > > > >
> > > > > On Wed, Apr 10, 2019 at 11:34 PM Jun Wu 
> wrote:
> > > > >
> > > > > > Dear Community,
> > > > > >
> > > > > > A while ago, we sent out an RFC
> > > > > > 
> > discussing
> > > > the
> > > > > > initiative introducing NumPy compatibility into MXNet. As the
> first
> > > > > outcome
> > > > > > of this initiative, we submitted the PR
> > > > > >  providing
> > the
> > > > > > infrastructure of supporting zero-dim (scalar) and zero-size
> > tensors,
> > > > > which
> > > > > > have been long-missing in MXNet.
> > > > > >
> > > > > > In our implementation, we have put the best efforts of keeping
> the
> > > > > promise
> > > > > > of backward compatibility in all the language bindings.
> > Nevertheless,
> > > > we
> > > > > > still would like to call out the changes explicitly that may
> impact
> > > > your
> > > > > > existing codebases developed on top of MXNet by calling C-APIs
> > > directly
> > > > > or
> > > > > > implementing operators in your own repos.
> > > > > >
> > > > > > 1. In you application, if you called any one of the following
> > > > > shape-related
> > > > > > C-APIs, you will need to change the data type of shape's ndim and
> > > > > dim_size
> > > > > > from *unsigned int* to signed *int*, because we have to use -1 to
> > > > > represent
> > > > > > unknown shape information, and reserve 0 for scalar and zero-size
> > > > > tensors.
> > > > > > One example of such changes can be seen in the cpp-package
> > > > > > <
> > > > > >
> > > > >
> > > >
> > >
> >
> https://github.com/apache/incubator-mxnet/pull/14661/files#diff-c0e1fcfe1619faa4ff5f59d94e8bR183
> > > > > > >
> > > > > > calling MXSymbolInferShape.
> > > > > > - MXSymbolInfershape
> > > > > > - MXSymbolInfershapePartial
> > > > > > - MXExecutorSimpleBind
> > > > > > - MXExecutorReshape
> > > > > > - MXNDArrayGetShape
> > > > > > - MXNDArrayCreaetFromSharedMem
> > > > > >
> > > > > > 2. If you have implemented operators in your own codebases, you
> > will
> > > > > > probably need to change every operator's 

Re: Implementing zero-dim and zero-size tensors in MXNet and its impact on your codebases

2019-04-11 Thread Marco de Abreu
Hi Jun,

we've had a previous discussion on this topic here:
https://lists.apache.org/thread.html/f0d7d96f9737479ec57580a977e9169544ffa1bc1a8ae21ab18fc6a0@%3Cdev.mxnet.apache.org%3E

Best regards,
Marco

On Thu, Apr 11, 2019 at 7:58 PM Jun Wu  wrote:

> I'm not sure about whether C APIs should fall under semver. This is the
> discussion we would like to have with the community.
>
> My thinking on this:
> 1. In most of the cases, C APIs only serve as bridges between frontend
> language bindings and C++ backend. Most of users/developers do not interact
> directly with C APIs.
> 2. The cases I can think of where C APIs are directly adopted in
> application development are model deployment in a C/C++ environment. In
> those cases, developers only interact with C Predict APIs, which we didn't
> touch.
>
> If the community feel that we are obliged to keep the semver for all C
> APIs, we can try to make a copy of the C APIs we intend to modify in the PR
> and keep the old signatures intact, this will introduce a lot of duplicate
> code though.
>
> On Thu, Apr 11, 2019 at 8:50 AM Anirudh Subramanian  >
> wrote:
>
> > I was under the impression that C API does fall under semver. Has this
> been
> > discussed somewhere before ? Is this also the case for C Predict API ?
> >
> > On Thu, Apr 11, 2019, 8:08 AM Marco de Abreu 
> > wrote:
> >
> > > In case only changes to the c-api are being made, it doesn't fall under
> > our
> > > semantic versioning since that's not a user facing API and thus I'd be
> in
> > > favour as doing it as part of a minor release. If there is any
> > behavioural
> > > change from a user perspective (a good indicator would be if tests have
> > to
> > > be changed as reaction to the Backend changes), then I'd prefer a major
> > > release.
> > >
> > > I'd slightly prefer a minor release since this change touches quite a
> few
> > > parts and could risk being outdated/diverged as the time until 2.0
> > > progresses.
> > >
> > > -Marco
> > >
> > > Aaron Markham  schrieb am Do., 11. Apr.
> 2019,
> > > 16:28:
> > >
> > > > Just curious about when this kind of change will land. Would it wait
> > for
> > > > 2.0 or would it be in 1.5 or another minor release?
> > > >
> > > > On Thu, Apr 11, 2019, 00:15 Junru Shao 
> > wrote:
> > > >
> > > > > Really nice improvement over MXNet's usability! I suggest that we
> > could
> > > > > make numpy-compatible behavior default in 2.0.
> > > > >
> > > > > On Wed, Apr 10, 2019 at 11:34 PM Jun Wu 
> wrote:
> > > > >
> > > > > > Dear Community,
> > > > > >
> > > > > > A while ago, we sent out an RFC
> > > > > > 
> > discussing
> > > > the
> > > > > > initiative introducing NumPy compatibility into MXNet. As the
> first
> > > > > outcome
> > > > > > of this initiative, we submitted the PR
> > > > > >  providing
> > the
> > > > > > infrastructure of supporting zero-dim (scalar) and zero-size
> > tensors,
> > > > > which
> > > > > > have been long-missing in MXNet.
> > > > > >
> > > > > > In our implementation, we have put the best efforts of keeping
> the
> > > > > promise
> > > > > > of backward compatibility in all the language bindings.
> > Nevertheless,
> > > > we
> > > > > > still would like to call out the changes explicitly that may
> impact
> > > > your
> > > > > > existing codebases developed on top of MXNet by calling C-APIs
> > > directly
> > > > > or
> > > > > > implementing operators in your own repos.
> > > > > >
> > > > > > 1. In you application, if you called any one of the following
> > > > > shape-related
> > > > > > C-APIs, you will need to change the data type of shape's ndim and
> > > > > dim_size
> > > > > > from *unsigned int* to signed *int*, because we have to use -1 to
> > > > > represent
> > > > > > unknown shape information, and reserve 0 for scalar and zero-size
> > > > > tensors.
> > > > > > One example of such changes can be seen in the cpp-package
> > > > > > <
> > > > > >
> > > > >
> > > >
> > >
> >
> https://github.com/apache/incubator-mxnet/pull/14661/files#diff-c0e1fcfe1619faa4ff5f59d94e8bR183
> > > > > > >
> > > > > > calling MXSymbolInferShape.
> > > > > > - MXSymbolInfershape
> > > > > > - MXSymbolInfershapePartial
> > > > > > - MXExecutorSimpleBind
> > > > > > - MXExecutorReshape
> > > > > > - MXNDArrayGetShape
> > > > > > - MXNDArrayCreaetFromSharedMem
> > > > > >
> > > > > > 2. If you have implemented operators in your own codebases, you
> > will
> > > > > > probably need to change every operator's shape inference function
> > to
> > > > use
> > > > > > the following util functions to check whether shape information
> is
> > > > known,
> > > > > > instead of checking against 0 directly. One example of such
> changes
> > > can
> > > > > be
> > > > > > seen in the shape inference function
> > > > > > <
> > > > > >
> > > > >
> > > >
> > >
> >
> 

Re: Implementing zero-dim and zero-size tensors in MXNet and its impact on your codebases

2019-04-11 Thread Jun Wu
I'm not sure about whether C APIs should fall under semver. This is the
discussion we would like to have with the community.

My thinking on this:
1. In most of the cases, C APIs only serve as bridges between frontend
language bindings and C++ backend. Most of users/developers do not interact
directly with C APIs.
2. The cases I can think of where C APIs are directly adopted in
application development are model deployment in a C/C++ environment. In
those cases, developers only interact with C Predict APIs, which we didn't
touch.

If the community feel that we are obliged to keep the semver for all C
APIs, we can try to make a copy of the C APIs we intend to modify in the PR
and keep the old signatures intact, this will introduce a lot of duplicate
code though.

On Thu, Apr 11, 2019 at 8:50 AM Anirudh Subramanian 
wrote:

> I was under the impression that C API does fall under semver. Has this been
> discussed somewhere before ? Is this also the case for C Predict API ?
>
> On Thu, Apr 11, 2019, 8:08 AM Marco de Abreu 
> wrote:
>
> > In case only changes to the c-api are being made, it doesn't fall under
> our
> > semantic versioning since that's not a user facing API and thus I'd be in
> > favour as doing it as part of a minor release. If there is any
> behavioural
> > change from a user perspective (a good indicator would be if tests have
> to
> > be changed as reaction to the Backend changes), then I'd prefer a major
> > release.
> >
> > I'd slightly prefer a minor release since this change touches quite a few
> > parts and could risk being outdated/diverged as the time until 2.0
> > progresses.
> >
> > -Marco
> >
> > Aaron Markham  schrieb am Do., 11. Apr. 2019,
> > 16:28:
> >
> > > Just curious about when this kind of change will land. Would it wait
> for
> > > 2.0 or would it be in 1.5 or another minor release?
> > >
> > > On Thu, Apr 11, 2019, 00:15 Junru Shao 
> wrote:
> > >
> > > > Really nice improvement over MXNet's usability! I suggest that we
> could
> > > > make numpy-compatible behavior default in 2.0.
> > > >
> > > > On Wed, Apr 10, 2019 at 11:34 PM Jun Wu  wrote:
> > > >
> > > > > Dear Community,
> > > > >
> > > > > A while ago, we sent out an RFC
> > > > > 
> discussing
> > > the
> > > > > initiative introducing NumPy compatibility into MXNet. As the first
> > > > outcome
> > > > > of this initiative, we submitted the PR
> > > > >  providing
> the
> > > > > infrastructure of supporting zero-dim (scalar) and zero-size
> tensors,
> > > > which
> > > > > have been long-missing in MXNet.
> > > > >
> > > > > In our implementation, we have put the best efforts of keeping the
> > > > promise
> > > > > of backward compatibility in all the language bindings.
> Nevertheless,
> > > we
> > > > > still would like to call out the changes explicitly that may impact
> > > your
> > > > > existing codebases developed on top of MXNet by calling C-APIs
> > directly
> > > > or
> > > > > implementing operators in your own repos.
> > > > >
> > > > > 1. In you application, if you called any one of the following
> > > > shape-related
> > > > > C-APIs, you will need to change the data type of shape's ndim and
> > > > dim_size
> > > > > from *unsigned int* to signed *int*, because we have to use -1 to
> > > > represent
> > > > > unknown shape information, and reserve 0 for scalar and zero-size
> > > > tensors.
> > > > > One example of such changes can be seen in the cpp-package
> > > > > <
> > > > >
> > > >
> > >
> >
> https://github.com/apache/incubator-mxnet/pull/14661/files#diff-c0e1fcfe1619faa4ff5f59d94e8bR183
> > > > > >
> > > > > calling MXSymbolInferShape.
> > > > > - MXSymbolInfershape
> > > > > - MXSymbolInfershapePartial
> > > > > - MXExecutorSimpleBind
> > > > > - MXExecutorReshape
> > > > > - MXNDArrayGetShape
> > > > > - MXNDArrayCreaetFromSharedMem
> > > > >
> > > > > 2. If you have implemented operators in your own codebases, you
> will
> > > > > probably need to change every operator's shape inference function
> to
> > > use
> > > > > the following util functions to check whether shape information is
> > > known,
> > > > > instead of checking against 0 directly. One example of such changes
> > can
> > > > be
> > > > > seen in the shape inference function
> > > > > <
> > > > >
> > > >
> > >
> >
> https://github.com/apache/incubator-mxnet/pull/14661/files#diff-afa640c4653c59f00f43a84455f91ef9R35
> > > > > >
> > > > > of concat operator.
> > > > > - shape_is_known (include/mxnet/tuple.h)
> > > > > - ndim_is_known (include/mxnet/tuple.h)
> > > > > - dim_size_is_known (include/mxnet/tuple.h)
> > > > >
> > > > > If you are interested in knowing the value of scalar tensors, and
> > hence
> > > > > understanding our motivation further, this thread
> > > > > <
> > https://discuss.mxnet.io/t/rank-0-arrays-in-mxnet-aka-pi-is-wrong/108
> > > >
> > > > of
> > > > > discussion provides very good 

Re: Implementing zero-dim and zero-size tensors in MXNet and its impact on your codebases

2019-04-11 Thread Anirudh Subramanian
I was under the impression that C API does fall under semver. Has this been
discussed somewhere before ? Is this also the case for C Predict API ?

On Thu, Apr 11, 2019, 8:08 AM Marco de Abreu 
wrote:

> In case only changes to the c-api are being made, it doesn't fall under our
> semantic versioning since that's not a user facing API and thus I'd be in
> favour as doing it as part of a minor release. If there is any behavioural
> change from a user perspective (a good indicator would be if tests have to
> be changed as reaction to the Backend changes), then I'd prefer a major
> release.
>
> I'd slightly prefer a minor release since this change touches quite a few
> parts and could risk being outdated/diverged as the time until 2.0
> progresses.
>
> -Marco
>
> Aaron Markham  schrieb am Do., 11. Apr. 2019,
> 16:28:
>
> > Just curious about when this kind of change will land. Would it wait for
> > 2.0 or would it be in 1.5 or another minor release?
> >
> > On Thu, Apr 11, 2019, 00:15 Junru Shao  wrote:
> >
> > > Really nice improvement over MXNet's usability! I suggest that we could
> > > make numpy-compatible behavior default in 2.0.
> > >
> > > On Wed, Apr 10, 2019 at 11:34 PM Jun Wu  wrote:
> > >
> > > > Dear Community,
> > > >
> > > > A while ago, we sent out an RFC
> > > >  discussing
> > the
> > > > initiative introducing NumPy compatibility into MXNet. As the first
> > > outcome
> > > > of this initiative, we submitted the PR
> > > >  providing the
> > > > infrastructure of supporting zero-dim (scalar) and zero-size tensors,
> > > which
> > > > have been long-missing in MXNet.
> > > >
> > > > In our implementation, we have put the best efforts of keeping the
> > > promise
> > > > of backward compatibility in all the language bindings. Nevertheless,
> > we
> > > > still would like to call out the changes explicitly that may impact
> > your
> > > > existing codebases developed on top of MXNet by calling C-APIs
> directly
> > > or
> > > > implementing operators in your own repos.
> > > >
> > > > 1. In you application, if you called any one of the following
> > > shape-related
> > > > C-APIs, you will need to change the data type of shape's ndim and
> > > dim_size
> > > > from *unsigned int* to signed *int*, because we have to use -1 to
> > > represent
> > > > unknown shape information, and reserve 0 for scalar and zero-size
> > > tensors.
> > > > One example of such changes can be seen in the cpp-package
> > > > <
> > > >
> > >
> >
> https://github.com/apache/incubator-mxnet/pull/14661/files#diff-c0e1fcfe1619faa4ff5f59d94e8bR183
> > > > >
> > > > calling MXSymbolInferShape.
> > > > - MXSymbolInfershape
> > > > - MXSymbolInfershapePartial
> > > > - MXExecutorSimpleBind
> > > > - MXExecutorReshape
> > > > - MXNDArrayGetShape
> > > > - MXNDArrayCreaetFromSharedMem
> > > >
> > > > 2. If you have implemented operators in your own codebases, you will
> > > > probably need to change every operator's shape inference function to
> > use
> > > > the following util functions to check whether shape information is
> > known,
> > > > instead of checking against 0 directly. One example of such changes
> can
> > > be
> > > > seen in the shape inference function
> > > > <
> > > >
> > >
> >
> https://github.com/apache/incubator-mxnet/pull/14661/files#diff-afa640c4653c59f00f43a84455f91ef9R35
> > > > >
> > > > of concat operator.
> > > > - shape_is_known (include/mxnet/tuple.h)
> > > > - ndim_is_known (include/mxnet/tuple.h)
> > > > - dim_size_is_known (include/mxnet/tuple.h)
> > > >
> > > > If you are interested in knowing the value of scalar tensors, and
> hence
> > > > understanding our motivation further, this thread
> > > > <
> https://discuss.mxnet.io/t/rank-0-arrays-in-mxnet-aka-pi-is-wrong/108
> > >
> > > of
> > > > discussion provides very good insights from the view of data science.
> > It
> > > > was actually related to an opportunity for MXNet becoming the backend
> > of
> > > > PyMC , but somehow it didn't go
> > > > through due to missing several key features
> > > > ,
> and
> > > > scalar tensors is one of them.
> > > >
> > > > Please leave comments in the PR
> > > >  if you have
> any
> > > > concerns or suggestions of our work.
> > > >
> > > > Thank you very much for your time and consideration.
> > > >
> > > > Best,
> > > > Jun
> > > >
> > > > *References*
> > > > [1] RFC of NumPy compatibility:
> > > > https://github.com/apache/incubator-mxnet/issues/14253
> > > > [2] Pull request of supporting scalar and zero-size tensors:
> > > > https://github.com/apache/incubator-mxnet/pull/14661
> > > > [3] The value of scalar tensors from the view of data science:
> > > >
> https://discuss.mxnet.io/t/rank-0-arrays-in-mxnet-aka-pi-is-wrong/108
> > > > 

Re: Implementing zero-dim and zero-size tensors in MXNet and its impact on your codebases

2019-04-11 Thread Marco de Abreu
In case only changes to the c-api are being made, it doesn't fall under our
semantic versioning since that's not a user facing API and thus I'd be in
favour as doing it as part of a minor release. If there is any behavioural
change from a user perspective (a good indicator would be if tests have to
be changed as reaction to the Backend changes), then I'd prefer a major
release.

I'd slightly prefer a minor release since this change touches quite a few
parts and could risk being outdated/diverged as the time until 2.0
progresses.

-Marco

Aaron Markham  schrieb am Do., 11. Apr. 2019,
16:28:

> Just curious about when this kind of change will land. Would it wait for
> 2.0 or would it be in 1.5 or another minor release?
>
> On Thu, Apr 11, 2019, 00:15 Junru Shao  wrote:
>
> > Really nice improvement over MXNet's usability! I suggest that we could
> > make numpy-compatible behavior default in 2.0.
> >
> > On Wed, Apr 10, 2019 at 11:34 PM Jun Wu  wrote:
> >
> > > Dear Community,
> > >
> > > A while ago, we sent out an RFC
> > >  discussing
> the
> > > initiative introducing NumPy compatibility into MXNet. As the first
> > outcome
> > > of this initiative, we submitted the PR
> > >  providing the
> > > infrastructure of supporting zero-dim (scalar) and zero-size tensors,
> > which
> > > have been long-missing in MXNet.
> > >
> > > In our implementation, we have put the best efforts of keeping the
> > promise
> > > of backward compatibility in all the language bindings. Nevertheless,
> we
> > > still would like to call out the changes explicitly that may impact
> your
> > > existing codebases developed on top of MXNet by calling C-APIs directly
> > or
> > > implementing operators in your own repos.
> > >
> > > 1. In you application, if you called any one of the following
> > shape-related
> > > C-APIs, you will need to change the data type of shape's ndim and
> > dim_size
> > > from *unsigned int* to signed *int*, because we have to use -1 to
> > represent
> > > unknown shape information, and reserve 0 for scalar and zero-size
> > tensors.
> > > One example of such changes can be seen in the cpp-package
> > > <
> > >
> >
> https://github.com/apache/incubator-mxnet/pull/14661/files#diff-c0e1fcfe1619faa4ff5f59d94e8bR183
> > > >
> > > calling MXSymbolInferShape.
> > > - MXSymbolInfershape
> > > - MXSymbolInfershapePartial
> > > - MXExecutorSimpleBind
> > > - MXExecutorReshape
> > > - MXNDArrayGetShape
> > > - MXNDArrayCreaetFromSharedMem
> > >
> > > 2. If you have implemented operators in your own codebases, you will
> > > probably need to change every operator's shape inference function to
> use
> > > the following util functions to check whether shape information is
> known,
> > > instead of checking against 0 directly. One example of such changes can
> > be
> > > seen in the shape inference function
> > > <
> > >
> >
> https://github.com/apache/incubator-mxnet/pull/14661/files#diff-afa640c4653c59f00f43a84455f91ef9R35
> > > >
> > > of concat operator.
> > > - shape_is_known (include/mxnet/tuple.h)
> > > - ndim_is_known (include/mxnet/tuple.h)
> > > - dim_size_is_known (include/mxnet/tuple.h)
> > >
> > > If you are interested in knowing the value of scalar tensors, and hence
> > > understanding our motivation further, this thread
> > >  >
> > of
> > > discussion provides very good insights from the view of data science.
> It
> > > was actually related to an opportunity for MXNet becoming the backend
> of
> > > PyMC , but somehow it didn't go
> > > through due to missing several key features
> > > , and
> > > scalar tensors is one of them.
> > >
> > > Please leave comments in the PR
> > >  if you have any
> > > concerns or suggestions of our work.
> > >
> > > Thank you very much for your time and consideration.
> > >
> > > Best,
> > > Jun
> > >
> > > *References*
> > > [1] RFC of NumPy compatibility:
> > > https://github.com/apache/incubator-mxnet/issues/14253
> > > [2] Pull request of supporting scalar and zero-size tensors:
> > > https://github.com/apache/incubator-mxnet/pull/14661
> > > [3] The value of scalar tensors from the view of data science:
> > > https://discuss.mxnet.io/t/rank-0-arrays-in-mxnet-aka-pi-is-wrong/108
> > > [4] Previous discussion for MXNet becoming the backend of PyMC:
> > > https://discuss.mxnet.io/t/moving-pymc3-from-theano-to-mxnet/86
> > >
> >
>


Re: Implementing zero-dim and zero-size tensors in MXNet and its impact on your codebases

2019-04-11 Thread Aaron Markham
Just curious about when this kind of change will land. Would it wait for
2.0 or would it be in 1.5 or another minor release?

On Thu, Apr 11, 2019, 00:15 Junru Shao  wrote:

> Really nice improvement over MXNet's usability! I suggest that we could
> make numpy-compatible behavior default in 2.0.
>
> On Wed, Apr 10, 2019 at 11:34 PM Jun Wu  wrote:
>
> > Dear Community,
> >
> > A while ago, we sent out an RFC
> >  discussing the
> > initiative introducing NumPy compatibility into MXNet. As the first
> outcome
> > of this initiative, we submitted the PR
> >  providing the
> > infrastructure of supporting zero-dim (scalar) and zero-size tensors,
> which
> > have been long-missing in MXNet.
> >
> > In our implementation, we have put the best efforts of keeping the
> promise
> > of backward compatibility in all the language bindings. Nevertheless, we
> > still would like to call out the changes explicitly that may impact your
> > existing codebases developed on top of MXNet by calling C-APIs directly
> or
> > implementing operators in your own repos.
> >
> > 1. In you application, if you called any one of the following
> shape-related
> > C-APIs, you will need to change the data type of shape's ndim and
> dim_size
> > from *unsigned int* to signed *int*, because we have to use -1 to
> represent
> > unknown shape information, and reserve 0 for scalar and zero-size
> tensors.
> > One example of such changes can be seen in the cpp-package
> > <
> >
> https://github.com/apache/incubator-mxnet/pull/14661/files#diff-c0e1fcfe1619faa4ff5f59d94e8bR183
> > >
> > calling MXSymbolInferShape.
> > - MXSymbolInfershape
> > - MXSymbolInfershapePartial
> > - MXExecutorSimpleBind
> > - MXExecutorReshape
> > - MXNDArrayGetShape
> > - MXNDArrayCreaetFromSharedMem
> >
> > 2. If you have implemented operators in your own codebases, you will
> > probably need to change every operator's shape inference function to use
> > the following util functions to check whether shape information is known,
> > instead of checking against 0 directly. One example of such changes can
> be
> > seen in the shape inference function
> > <
> >
> https://github.com/apache/incubator-mxnet/pull/14661/files#diff-afa640c4653c59f00f43a84455f91ef9R35
> > >
> > of concat operator.
> > - shape_is_known (include/mxnet/tuple.h)
> > - ndim_is_known (include/mxnet/tuple.h)
> > - dim_size_is_known (include/mxnet/tuple.h)
> >
> > If you are interested in knowing the value of scalar tensors, and hence
> > understanding our motivation further, this thread
> > 
> of
> > discussion provides very good insights from the view of data science. It
> > was actually related to an opportunity for MXNet becoming the backend of
> > PyMC , but somehow it didn't go
> > through due to missing several key features
> > , and
> > scalar tensors is one of them.
> >
> > Please leave comments in the PR
> >  if you have any
> > concerns or suggestions of our work.
> >
> > Thank you very much for your time and consideration.
> >
> > Best,
> > Jun
> >
> > *References*
> > [1] RFC of NumPy compatibility:
> > https://github.com/apache/incubator-mxnet/issues/14253
> > [2] Pull request of supporting scalar and zero-size tensors:
> > https://github.com/apache/incubator-mxnet/pull/14661
> > [3] The value of scalar tensors from the view of data science:
> > https://discuss.mxnet.io/t/rank-0-arrays-in-mxnet-aka-pi-is-wrong/108
> > [4] Previous discussion for MXNet becoming the backend of PyMC:
> > https://discuss.mxnet.io/t/moving-pymc3-from-theano-to-mxnet/86
> >
>


Re: Implementing zero-dim and zero-size tensors in MXNet and its impact on your codebases

2019-04-11 Thread Junru Shao
Really nice improvement over MXNet's usability! I suggest that we could
make numpy-compatible behavior default in 2.0.

On Wed, Apr 10, 2019 at 11:34 PM Jun Wu  wrote:

> Dear Community,
>
> A while ago, we sent out an RFC
>  discussing the
> initiative introducing NumPy compatibility into MXNet. As the first outcome
> of this initiative, we submitted the PR
>  providing the
> infrastructure of supporting zero-dim (scalar) and zero-size tensors, which
> have been long-missing in MXNet.
>
> In our implementation, we have put the best efforts of keeping the promise
> of backward compatibility in all the language bindings. Nevertheless, we
> still would like to call out the changes explicitly that may impact your
> existing codebases developed on top of MXNet by calling C-APIs directly or
> implementing operators in your own repos.
>
> 1. In you application, if you called any one of the following shape-related
> C-APIs, you will need to change the data type of shape's ndim and dim_size
> from *unsigned int* to signed *int*, because we have to use -1 to represent
> unknown shape information, and reserve 0 for scalar and zero-size tensors.
> One example of such changes can be seen in the cpp-package
> <
> https://github.com/apache/incubator-mxnet/pull/14661/files#diff-c0e1fcfe1619faa4ff5f59d94e8bR183
> >
> calling MXSymbolInferShape.
> - MXSymbolInfershape
> - MXSymbolInfershapePartial
> - MXExecutorSimpleBind
> - MXExecutorReshape
> - MXNDArrayGetShape
> - MXNDArrayCreaetFromSharedMem
>
> 2. If you have implemented operators in your own codebases, you will
> probably need to change every operator's shape inference function to use
> the following util functions to check whether shape information is known,
> instead of checking against 0 directly. One example of such changes can be
> seen in the shape inference function
> <
> https://github.com/apache/incubator-mxnet/pull/14661/files#diff-afa640c4653c59f00f43a84455f91ef9R35
> >
> of concat operator.
> - shape_is_known (include/mxnet/tuple.h)
> - ndim_is_known (include/mxnet/tuple.h)
> - dim_size_is_known (include/mxnet/tuple.h)
>
> If you are interested in knowing the value of scalar tensors, and hence
> understanding our motivation further, this thread
>  of
> discussion provides very good insights from the view of data science. It
> was actually related to an opportunity for MXNet becoming the backend of
> PyMC , but somehow it didn't go
> through due to missing several key features
> , and
> scalar tensors is one of them.
>
> Please leave comments in the PR
>  if you have any
> concerns or suggestions of our work.
>
> Thank you very much for your time and consideration.
>
> Best,
> Jun
>
> *References*
> [1] RFC of NumPy compatibility:
> https://github.com/apache/incubator-mxnet/issues/14253
> [2] Pull request of supporting scalar and zero-size tensors:
> https://github.com/apache/incubator-mxnet/pull/14661
> [3] The value of scalar tensors from the view of data science:
> https://discuss.mxnet.io/t/rank-0-arrays-in-mxnet-aka-pi-is-wrong/108
> [4] Previous discussion for MXNet becoming the backend of PyMC:
> https://discuss.mxnet.io/t/moving-pymc3-from-theano-to-mxnet/86
>


Implementing zero-dim and zero-size tensors in MXNet and its impact on your codebases

2019-04-11 Thread Jun Wu
Dear Community,

A while ago, we sent out an RFC
 discussing the
initiative introducing NumPy compatibility into MXNet. As the first outcome
of this initiative, we submitted the PR
 providing the
infrastructure of supporting zero-dim (scalar) and zero-size tensors, which
have been long-missing in MXNet.

In our implementation, we have put the best efforts of keeping the promise
of backward compatibility in all the language bindings. Nevertheless, we
still would like to call out the changes explicitly that may impact your
existing codebases developed on top of MXNet by calling C-APIs directly or
implementing operators in your own repos.

1. In you application, if you called any one of the following shape-related
C-APIs, you will need to change the data type of shape's ndim and dim_size
from *unsigned int* to signed *int*, because we have to use -1 to represent
unknown shape information, and reserve 0 for scalar and zero-size tensors.
One example of such changes can be seen in the cpp-package

calling MXSymbolInferShape.
- MXSymbolInfershape
- MXSymbolInfershapePartial
- MXExecutorSimpleBind
- MXExecutorReshape
- MXNDArrayGetShape
- MXNDArrayCreaetFromSharedMem

2. If you have implemented operators in your own codebases, you will
probably need to change every operator's shape inference function to use
the following util functions to check whether shape information is known,
instead of checking against 0 directly. One example of such changes can be
seen in the shape inference function

of concat operator.
- shape_is_known (include/mxnet/tuple.h)
- ndim_is_known (include/mxnet/tuple.h)
- dim_size_is_known (include/mxnet/tuple.h)

If you are interested in knowing the value of scalar tensors, and hence
understanding our motivation further, this thread
 of
discussion provides very good insights from the view of data science. It
was actually related to an opportunity for MXNet becoming the backend of
PyMC , but somehow it didn't go
through due to missing several key features
, and
scalar tensors is one of them.

Please leave comments in the PR
 if you have any
concerns or suggestions of our work.

Thank you very much for your time and consideration.

Best,
Jun

*References*
[1] RFC of NumPy compatibility:
https://github.com/apache/incubator-mxnet/issues/14253
[2] Pull request of supporting scalar and zero-size tensors:
https://github.com/apache/incubator-mxnet/pull/14661
[3] The value of scalar tensors from the view of data science:
https://discuss.mxnet.io/t/rank-0-arrays-in-mxnet-aka-pi-is-wrong/108
[4] Previous discussion for MXNet becoming the backend of PyMC:
https://discuss.mxnet.io/t/moving-pymc3-from-theano-to-mxnet/86