> How would you plan to update Boost even within the ecosystem?

Yep, maintainers have been automatically updating the version pins
across the ecosystem. Example pin:
https://github.com/conda-forge/arrow-cpp-feedstock/pull/44

Just to put this sentiment out there publicly, and it's not really an
"Arrow problem" -- it seems inevitable (on a 20 year horizon -- who
knows how long it will actually take) that we will see something like
conda-forge develop with the following features:

* Is essentially a monorepo build system for a hybrid OSS development
setup like you're describing
* Can be run on your own cloud infrastructure / VPC, with support
tooling for building in an air-gapped / no-internet environment
* Reproducible runtime environments a la conda
* Build open source dependencies and your closed source dependencies
using the same build toolchain. Updating a package version triggers
all downstream dependencies to rebuild
* Support for nightly / bleeding edge builds of any group of
interdependent packages, installable from a $FOO-nightly "channel" to
use "conda" lingo
* Any package can be configured to run unit tests as part of the
package validation process
* Non-hostile UX for developers -- conda-forge is rife with problems
and a routine time suck for all of us. For example, conducting a
cascade of interdependent changes is a nightmare (Arrow C++ -> Parquet
C++ -> Arrow Python)

Basically, this should be something like Bazel + Docker (with some
alternative solution for Windows users) + conda, with nice tooling and
UI. Or, to put it another way, a DIY, self-governed version of what
Anaconda Inc. and conda-forge are collectively providing to the
community.

I have long argued that centralized packaging systems are a liability
to OSS consumers ([1], [2]). But it's hard to build your own toolchain
from the bottom up. I don't see why it *needs* to be so hard.

LargeCos like Google have already solved this problem for themselves,
but their solutions are not easily accessible to most. It's great that
the build systems (like Bazel) are being open sourced, but there's a
lot more stuff that needs to get built to make things easier for shops
with less devops resources.

If someone wants to build this "Monorepo System of your Dreams",
please take this idea and run with it and you'll have me as a happy
customer someday. I'm not passionate enough about packaging and devops
alone to work on it personally, though the tooling is causing me and
so many people I know so much pain I'm not sure where to turn right
now.

- Wes

[1]: http://wesmckinney.com/blog/conda-forge-centos-moment/
[2]: http://wesmckinney.com/blog/the-problem-with-conda-forge-right-now/

On Sat, Feb 17, 2018 at 4:33 PM, Alex Samuel <a...@alexsamuel.net> wrote:
> Sorry, I think I wasn't clear.  I mean the broader issue of C++ extension
> code.  In principle it should be possible to mix C++ extension modules in
> the same Python process, at least in some cases, especially if they link
> their own dependencies statically.  While "just do it our way, use our
> tools" is fine for most cases, it might not be fine for some, for a wide
> variety of reasons.  If everyone could agree on C++ compilers and libraries,
> Linux distros would have standardized ages ago I suppose.  This isn't a
> conda-specific problem; however for conda it becomes a runtime problem
> rather than a build-time one.  But I concede it's a hard problem.  Mainly,
> what I'm suggesting is that the policies and use cases be explicit.  Thanks
> for clarifying.
>
> Regarding Boost particularly, all I meant was that the Boost dependency
> wasn't apparent in the usual ways, which made debugging problems harder.
>
> How would you plan to update Boost even within the ecosystem?  Bump the
> version in the toolchain, rebuild the world, and update all environments?
> Without explicit dependency, how do you prevent someone from running parquet
> statically linked to Boost N from running in an environment with
> boost-cpp==N+1 installed?
>
> Thanks,
> Alex
>
>
>
>
>
> On 02/17/2018 04:20 PM, Wes McKinney wrote:
>>>
>>> However, extension modules are always going to have to share the Python
>>> process, so this policy kind of says, you can't use external C++ extension
>>> code with conda.
>>
>>
>> This is a bit too extreme. What I meant is that you should try not to
>> mix C++ build toolchains. I think this is good advice even without
>> conda/conda-forge in the loop. If conda-forge were supplying the
>> library / build toolchain for the rest of your projects, then
>> everything would be OK.
>>
>>> Given the policy, it seems slightly better to link Boost dynamically.
>>
>>
>> We could do this, but it seems like a last resort workaround to the
>> core problem, which is the mixed build toolchain issue. I don't know
>> what Boost's ABI guarantees are, but dynamic linking isn't guaranteed
>> to solve using two libraries built against different versions of Boost
>> in the same process. The boost-cpp package is a pretty chunky runtime
>> dependency also. We could give it a shot and see how it goes in the
>> next release cycle.
>>
>> - Wes
>>
>> On Sat, Feb 17, 2018 at 4:06 PM, Alex Samuel <a...@alexsamuel.net> wrote:
>>>
>>> OK.
>>>
>>> I'll probably be able to work around this problem.  Just a couple of
>>> thoughts for the long term:
>>>
>>> 1. It seems mostly reasonable to treat conda as closed ecosystem as you
>>> describe; other C++ stuff can be deployed by other means.  However,
>>> extension modules are always going to have to share the Python process,
>>> so
>>> this policy kind of says, you can't use external C++ extension code with
>>> conda.
>>>
>>> 2. Given the policy, it seems slightly better to link Boost dynamically.
>>> I
>>> had checked package metadata and shared lib dependencies, and didn't even
>>> realize it used Boost, until one of my colleagues actually looked at the
>>> symbol table and pointed this out.  As it stands, Boost is an undeclared
>>> dependency, at least "dependency" in the sense of pinning a version.
>>>
>>> Thanks for your help.
>>> Alex
>>>
>>>
>>>
>>> On 02/17/2018 11:32 AM, Wes McKinney wrote:
>>>>
>>>>
>>>> It sounds like for your use case that it would be better for you to
>>>> build your own Arrow packages that use the same Boost as the rest of
>>>> your repo. You can possible use the scourge tool that Phillip built to
>>>> help with this (we're using it to build nightlies).
>>>>
>>>> conda-forge is a fairly closed ecosystem under the present
>>>> circumstances -- the intent is that libraries within it are
>>>> interoperable with each other, and that packages built with
>>>> conda-forge binaries as their third party dependencies (e.g. if you
>>>> were using the boost-cpp conda-forge package) will also be able to
>>>> work. Using the conda-forge stack as an add-on to a substantial
>>>> independent C++ library stack is not (IIUC) an intended use case.
>>>>
>>>> Note that there are libstdc++-related issues using conda-forge
>>>> binaries with Anaconda >= 5.0 due to the change in compilers.
>>>> Hopefully this will get fixed in the next few months.
>>>>
>>>> - Wes
>>>>
>>>> On Sat, Feb 17, 2018 at 11:14 AM, Alex Samuel <a...@alexsamuel.net>
>>>> wrote:
>>>>>
>>>>>
>>>>> OK, though if both modules linked Boost statically, I believe they
>>>>> would
>>>>> have distinct copies of global variables.  Whether or not this causes
>>>>> problems depends on whether they are purely internal or tied to
>>>>> external
>>>>> state.  My hunch is that for Boost::regex, there wouldn't be an issue
>>>>> with
>>>>> two complete copies in the same process, as long as they remained
>>>>> separate.
>>>>> I still suspect our module is picking up some symbols from the copy of
>>>>> Boost
>>>>> statically linked to Parquet rather than the one it pulls in as a
>>>>> shared
>>>>> lib
>>>>> dependency.  One thing I could try is to link ours statically as well.
>>>>>
>>>>> I wasn't aware of bcp; I'll take a look at that.
>>>>>
>>>>> It may or may not be possible for us to build our C++ stuff against
>>>>> conda-forge's Boost; I'm not sure.  We have a large C++ codebase and
>>>>> distribute parts of it, particularly Python extension modules, via
>>>>> conda.
>>>>>
>>>>> In general, I suspect as conda-forge grows and packages more C++ code,
>>>>> issues like this are likely to become an increasing problem.  Do you
>>>>> know
>>>>> if
>>>>> there is a general policy regarding how extension modules in conda
>>>>> packages
>>>>> should link common C++ libraries like Boost?
>>>>>
>>>>> Thanks,
>>>>> Alex
>>>>>
>>>>>
>>>>>
>>>>>
>>>>> On 02/17/2018 11:04 AM, Uwe L. Korn wrote:
>>>>>>
>>>>>>
>>>>>>
>>>>>> Static linking does not really solve all problems in the Boost case as
>>>>>> there are global variables that are picked up across different Boost
>>>>>> versions. Thus if you link it statically it still has an effect on
>>>>>> other
>>>>>> dependencies. In the case of boost, you can get around this by using
>>>>>> the
>>>>>> bcp
>>>>>> tool
>>>>>> http://www.boost.org/doc/libs/1_66_0/tools/bcp/doc/html/index.html
>>>>>> to
>>>>>> rename your local boost to a different namespace to avoid collisions.
>>>>>> We
>>>>>> will also do thus in future with our wheel in Arrow, too. But we will
>>>>>> not do
>>>>>> this for conda-packages as there the assumption is that all artefacts
>>>>>> will
>>>>>> be linked against the same Boost version.
>>>>>>
>>>>>> Uwe
>>>>>>
>>>>>>> Am 17.02.2018 um 16:55 schrieb Alex Samuel <a...@alexsamuel.net>:
>>>>>>>
>>>>>>> Yes, we do link our internal code with a different Boost version; we
>>>>>>> build and (conda) package it ourselves.
>>>>>>>
>>>>>>> Why should this matter if Parquet links it statically?  If static
>>>>>>> linking
>>>>>>> won't allow us to use our own version, why bother linking statically
>>>>>>> at
>>>>>>> all?
>>>>>>>
>>>>>>> Thanks,
>>>>>>> Alex
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>> On 02/17/2018 10:52 AM, Uwe L. Korn wrote:
>>>>>>>> Hi,
>>>>>>>> The issue is here no that Boost is linked statically in one and
>>>>>>>> dynamically in another but that you link against two different boost
>>>>>>>> versions. The stacktrace shows links to Boost 1.55 whereas Arrow
>>>>>>>> should be
>>>>>>>> linked against 1.65 or 1.66 (the one coming from conda-forge). Arrow
>>>>>>>> requires at least a Boost version of 1.60+ to work. The most likely
>>>>>>>> guess
>>>>>>>> from my side would be that your internal modules are linked against
>>>>>>>> the
>>>>>>>> system boost, not the conda-provided boost.
>>>>>>>> Uwe
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> Am 17.02.2018 um 16:47 schrieb Alex Samuel <a...@alexsamuel.net>:
>>>>>>>>>
>>>>>>>>> Hi there,
>>>>>>>>>
>>>>>>>>> Sure, I'll append top of the stack.  You can see our internal
>>>>>>>>> function
>>>>>>>>> "asd::infra::util::start_of_date"; everything else is Boost,
>>>>>>>>> Python,
>>>>>>>>> or
>>>>>>>>> libstdc++.
>>>>>>>>>
>>>>>>>>> My understanding (though I haven't demonstrated this conclusively)
>>>>>>>>> is
>>>>>>>>> that, because Python loads extension modules RTLD_GLOBAL, an
>>>>>>>>> extension
>>>>>>>>> module can pick up symbols from another or its dependencies, even
>>>>>>>>> if
>>>>>>>>> the
>>>>>>>>> former "usually" satisfy relocations from their own shared lib
>>>>>>>>> dependencies.
>>>>>>>>> So, one module linking Boost statically may interfere with another
>>>>>>>>> that
>>>>>>>>> links it dynamically, by injecting its symbols.
>>>>>>>>>
>>>>>>>>> If necessary I can try to put together a minimal test case, but no
>>>>>>>>> guarantee it will actually trigger the bug.  But it might be worth
>>>>>>>>> testing
>>>>>>>>> my theory above first, with gdb or by some other means.
>>>>>>>>>
>>>>>>>>> Thanks!
>>>>>>>>> Alex
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> #0  0x00007f6ddeba4c8b in std::basic_string<char,
>>>>>>>>> std::char_traits<char>, std::allocator<char>
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>> ::basic_string(std::basic_string<char, std::char_traits<char>,
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> std::allocator<char> > const&) ()
>>>>>>>>>
>>>>>>>>>      from
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> /space/asd/conda/envs/rd-20180212-0/lib/python2.7/site-packages/numexpr/../../../libstdc++.so.6
>>>>>>>>>
>>>>>>>>> #1  0x00007f6dd4f978d6 in
>>>>>>>>> boost::re_detail::cpp_regex_traits_char_layer<char>::init() ()
>>>>>>>>>
>>>>>>>>>      from
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> /space/asd/conda/envs/rd-20180212-0/lib/python2.7/site-packages/asd/infra/../../../.././libboost_regex.so.1.55.0
>>>>>>>>>
>>>>>>>>> #2  0x00007f6dd4fdbd88 in
>>>>>>>>> boost::object_cache<boost::re_detail::cpp_regex_traits_base<char>,
>>>>>>>>> boost::re_detail::cpp_regex_traits_implementation<char>
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>> ::do_get(boost::re_detail::cpp_regex_traits_base<char> const&,
>>>>>>>>>> unsigned
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> long) ()
>>>>>>>>>
>>>>>>>>>      from
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> /space/asd/conda/envs/rd-20180212-0/lib/python2.7/site-packages/asd/infra/../../../.././libboost_regex.so.1.55.0
>>>>>>>>>
>>>>>>>>> #3  0x00007f6dd4fe5bb5 in boost::basic_regex<char,
>>>>>>>>> boost::regex_traits<char, boost::cpp_regex_traits<char> >
>>>>>>>>>>
>>>>>>>>>> ::do_assign(char
>>>>>>>>>
>>>>>>>>> const*, char const*, unsigned int) ()
>>>>>>>>>
>>>>>>>>>      from
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> /space/asd/conda/envs/rd-20180212-0/lib/python2.7/site-packages/asd/infra/../../../.././libboost_regex.so.1.55.0
>>>>>>>>>
>>>>>>>>> #4  0x00007f6dd575a90e in
>>>>>>>>> asd::infra::util::start_of_date(std::basic_string<char,
>>>>>>>>> std::char_traits<char>, std::allocator<char> > const&, char const*)
>>>>>>>>> ()
>>>>>>>>>
>>>>>>>>>       at
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> /prod/sys/sysasd/opt/tudor-devtools/v1.3/Linux.el6.x86_64-corei7-avx-gcc4.83-anaconda2.0.1/include/boost/regex/v4/basic_regex.hpp:382
>>>>>>>>>
>>>>>>>>> #5  0x00007f6dd2c36734 in
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> boost::python::objects::caller_py_function_impl<boost::python::detail::caller<unsigned
>>>>>>>>> long (*)(std::basic_string<char, std::char_traits<char>,
>>>>>>>>> std::allocator<char> > const&, char const*),
>>>>>>>>> boost::python::default_call_policies, boost::mpl::vector3<unsigned
>>>>>>>>> long,
>>>>>>>>> std::basic_string<char, std::char_traits<char>,
>>>>>>>>> std::allocator<char>
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>> const&, char const*> > >::operator()(_object*, _object*) ()
>>>>>>>>>
>>>>>>>>>      from
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> /space/asd/conda/envs/rd-20180212-0/lib/python2.7/site-packages/asd/infra/util.so
>>>>>>>>>
>>>>>>>>> #6  0x00007f6dd52ac71a in
>>>>>>>>> boost::python::objects::function::call(_object*, _object*) const ()
>>>>>>>>>
>>>>>>>>>      from
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> /space/asd/conda/envs/rd-20180212-0/lib/python2.7/site-packages/asd/infra/../../../../libboost_python.so.1.55.0
>>>>>>>>>
>>>>>>>>> #7  0x00007f6dd52aca68 in
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> boost::detail::function::void_function_ref_invoker0<boost::python::objects::(anonymous
>>>>>>>>> namespace)::bind_return,
>>>>>>>>> void>::invoke(boost::detail::function::function_buffer&) ()
>>>>>>>>>
>>>>>>>>>      from
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> /space/asd/conda/envs/rd-20180212-0/lib/python2.7/site-packages/asd/infra/../../../../libboost_python.so.1.55.0
>>>>>>>>>
>>>>>>>>> #8  0x00007f6dd52b4cd3 in
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> boost::python::detail::exception_handler::operator()(boost::function0<void>
>>>>>>>>> const&) const ()
>>>>>>>>>
>>>>>>>>>      from
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> /space/asd/conda/envs/rd-20180212-0/lib/python2.7/site-packages/asd/infra/../../../../libboost_python.so.1.55.0
>>>>>>>>>
>>>>>>>>> #9  0x00007f6dd2c32c03 in
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> boost::detail::function::function_obj_invoker2<boost::_bi::bind_t<bool,
>>>>>>>>> boost::python::detail::translate_exception<asd::infra::Exception,
>>>>>>>>> void
>>>>>>>>> (*)(asd::infra::Exception const&)>,
>>>>>>>>> boost::_bi::list3<boost::arg<1>,
>>>>>>>>> boost::arg<2>, boost::_bi::value<void (*)(asd::infra::Exception
>>>>>>>>> const&)> >
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>> , bool, boost::python::detail::exception_handler const&,
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> boost::function0<void>
>>>>>>>>> const&>::invoke(boost::detail::function::function_buffer&,
>>>>>>>>> boost::python::detail::exception_handler const&,
>>>>>>>>> boost::function0<void>
>>>>>>>>> const&) ()
>>>>>>>>>
>>>>>>>>>      from
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> /space/asd/conda/envs/rd-20180212-0/lib/python2.7/site-packages/asd/infra/util.so
>>>>>>>>>
>>>>>>>>> #10 0x00007f6dd52b4a9d in
>>>>>>>>> boost::python::handle_exception_impl(boost::function0<void>) ()
>>>>>>>>>
>>>>>>>>>      from
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> /space/asd/conda/envs/rd-20180212-0/lib/python2.7/site-packages/asd/infra/../../../../libboost_python.so.1.55.0
>>>>>>>>>
>>>>>>>>> #11 0x00007f6dd52ab2b3 in function_call ()
>>>>>>>>>
>>>>>>>>>      from
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> /space/asd/conda/envs/rd-20180212-0/lib/python2.7/site-packages/asd/infra/../../../../libboost_python.so.1.55.0
>>>>>>>>>
>>>>>>>>> #12 0x00007f6df2bc8e93 in PyObject_Call (func=0x2799850, arg=<value
>>>>>>>>> optimized out>,
>>>>>>>>>
>>>>>>>>>       kw=<value optimized out>) at Objects/abstract.c:2547
>>>>>>>>>
>>>>>>>>> #13 0x00007f6df2c7b80d in do_call (f=<value optimized out>,
>>>>>>>>> throwflag=<value optimized out>)
>>>>>>>>>
>>>>>>>>>       at Python/ceval.c:4569
>>>>>>>>>
>>>>>>>>> #14 call_function (f=<value optimized out>, throwflag=<value
>>>>>>>>> optimized
>>>>>>>>> out>) at Python/ceval.c:4374
>>>>>>>>>
>>>>>>>>> #15 PyEval_EvalFrameEx (f=<value optimized out>, throwflag=<value
>>>>>>>>> optimized out>) at Python/ceval.c:2989
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>> On 02/17/2018 10:31 AM, Uwe L. Korn wrote:
>>>>>>>>>> Hello,
>>>>>>>>>> I am not sure why we are linking statically in the conda-forge
>>>>>>>>>> packages, as a gut feeling we should link dynamically there. Wes,
>>>>>>>>>> can you
>>>>>>>>>> remember why?
>>>>>>>>>> Alex, would it be possible for you to send us the part of the
>>>>>>>>>> segmentation fault that is not private to your modules. That would
>>>>>>>>>> be a good
>>>>>>>>>> indicator for us what is going wrong.
>>>>>>>>>> Typically it is best when you enable coredumps with `ulimit -c
>>>>>>>>>> unlimited` and then run your program as usual. There should be no
>>>>>>>>>> performance penalty. When ist segfaults, run `gdb python core`
>>>>>>>>>> (note
>>>>>>>>>> that
>>>>>>>>>> the core file might also be postfixed with the PID but that
>>>>>>>>>> depends
>>>>>>>>>> on your
>>>>>>>>>> system). In gdb type 'thread apply all bt full'. Post thd output
>>>>>>>>>> pf
>>>>>>>>>> that
>>>>>>>>>> command and strip away the parts we should not see. Most relevant
>>>>>>>>>> will be
>>>>>>>>>> the stacktrace of the thread that segfaulted.
>>>>>>>>>> Uwe
>>>>>>>>>>>
>>>>>>>>>>>
>>>>>>>>>>>
>>>>>>>>>>> Am 16.02.2018 um 23:17 schrieb Alex Samuel <a...@alexsamuel.net>:
>>>>>>>>>>>
>>>>>>>>>>> Hello,
>>>>>>>>>>>
>>>>>>>>>>> I am having some troubles using the Continuum PyArrow conda
>>>>>>>>>>> package
>>>>>>>>>>> dependencies in conjunction with internal C++ extension modules.
>>>>>>>>>>>
>>>>>>>>>>> Apparently, Arrow and Parquet link Boost statically.  We have
>>>>>>>>>>> some
>>>>>>>>>>> internal packages containing C++ code that linking Boost libs
>>>>>>>>>>> dynamicaly.
>>>>>>>>>>> If we import Feather as well as our own extension modules into
>>>>>>>>>>> the
>>>>>>>>>>> same
>>>>>>>>>>> Python process, we get random segfaults in Boost.  I think what's
>>>>>>>>>>> happening
>>>>>>>>>>> is that our extension modules are picking up Boost's symbols from
>>>>>>>>>>> Arrow and
>>>>>>>>>>> Parquet already loaded into the process, rather than from our own
>>>>>>>>>>> Boost
>>>>>>>>>>> shared libs.
>>>>>>>>>>>
>>>>>>>>>>> Could anyone explain the policy for linking Boost in binary
>>>>>>>>>>> distributions, particularly conda packages?  What is your
>>>>>>>>>>> expectation for
>>>>>>>>>>> how other C++ extension modules should be built?
>>>>>>>>>>>
>>>>>>>>>>> Thanks in advance,
>>>>>>>>>>> Alex
>>>>>>>>>>>
>>>>>>
>>>>>
>>>
>

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