[llvm-dev] [lldb-dev] [cfe-dev] [Call for Volunteers] Bug triaging

[James Henderson via llvm-dev]

TLDR; Please don't just straight-up remove components based on some
arbitrary numeric threshold.

Just because a component doesn't get many bugs filed against it doesn't
mean it isn't useful. It might just mean that the area is generally pretty
stable or simply new. A good example to work with are the LLVM binary
utilities, such as llvm-objdump, llvm-obcopy, llvm-strings etc. Basically
all of these tools have a non-trivial amount of their code in their own
source files, not shared more widely, but are individually still pretty
small compared to the rest of the LLVM framework. As a result, bugs in them
are unlikely to be shared with other tools (at least in terms of the
cause). Let's say I only ship llvm-strings from the LLVM tools. I therefore
only care about bugs in llvm-strings, and not in all the other dozen or
more LLVM tools, which would end up in the "Tools: all bugs" category. I
don't want to risk missing a bug in the llvm-strings tool because there are
too many other bugs around. Same logic applies to each of the other tools.

Another issue with categories like "Other" is that people inevitably NEVER
decide to break off a new component from it (trust me, I've seen this
happen time and again with source sub-trees like "generic", "utilities",
"common" etc), so you end up with Other categories with dozens of bugs that
are difficult to immediately filter from one another. We have this issue
already with "new-bugs": I recently went through and moved all
llvm-readoj/llvm-readelf bugs into a new component to filter them from the
soup of "new-bugs", but even so this was only half a dozen. Let's take the
LLVM binutils as an example again. I'm going to pick on llvm-objcopy
because it is a new tool that likely doesn't have that many end-users yet
(it's not a reflection on the tool's quality!). As discussed, under the
suggested proposal of grouping few-bug components under All bugs/Other etc,
llvm-objcopy will end up under "Tools: all bugs". Let's say that a major OS
starts shipping llvm-objcopy instead of GNU objcopy. This will suddenly
massively increase the exposure of the tool, and potentially therefore the
number of bugs reported against it. As there is no sub-component for
llvm-objcopy, the bugs under Tools: all bugs will likely become dominated
by llvm-objcopy, drowning out the issues with other tools. Yes, at that
point we should break off the component, but I can almost guarantee that
this will never happen (how do you set a threshold and whose responsibility
is it to monitor that threshold? What if at some future point the number of
bugs drops below that threshold?).

I said this in the BoF, and I think from an end user's point of view
reporting bugs, they will in the first instance look for an executable
component with the same name, so I personally believe every executable
should have its own component, or for larger executables, e.g. clang and
LLD, a product. Additionally, where there's a clearly defined split between
large blocks of code within a large tool (e.g. LLD's COFF/ELF/Mach-O), then
those should be separate components, since it's likely straightforward
enough to tell which it should be in. I'm not so familiar with the library
structure of the main backend and clang, since I don't regularly develop in
those areas, so I'm more willing to defer to others on what further
break-downs should be in that area. However, it seems clear that areas of
expertise should be cleanly separated where possible (e.g. a "DWARF"
component makes a lot of sense).

Maybe there should be an "Unknown" component under every Product to catch
those where the user really doesn't know, but I'd prefer that to an "Other"
component for reasons discussed above, as the triagers for this should
first try to move it to the appropriate component (or potentially request a
new one).

James

On Fri, 9 Nov 2018 at 19:48, via lldb-dev <lldb-dev at lists.llvm.org> wrote:

> I also think that backends are a special case, and each should have its
> own component.  Also a code owner, which I think is already the case; and
> just like ensuring patches get reviewed, a backend code owner should ensure
> there is a triager.  It makes the list of components a bit longer, but adds
> no confusion to anyone trying to file a bug.
>
>
>
> Actually I'd say "libraries" as a higher-level component is more
> confusing, as a newcomer essentially never has to deal with LLVM libraries
> as a concept.
>
> --paulr
>
>
>
> *From:* lldb-dev [mailto:lldb-dev-bounces at lists.llvm.org] *On Behalf Of *Zachary
> Turner via lldb-dev
> *Sent:* Friday, November 09, 2018 2:35 PM
> *To:* Derek Schuff
> *Cc:* llvm-dev; Kristof Beyls; nd; Clang Dev; LLDB Dev
> *Subject:* Re: [lldb-dev] [llvm-dev] [cfe-dev] [Call for Volunteers] Bug
> triaging
>
>
>
> I had considered a libraries/Backends:Other as well that would be separate
> from libraries/Other
>
>
>
> On Fri, Nov 9, 2018 at 11:20 AM Derek Schuff <dschuff at google.com> wrote:
>
> I wonder if backends are a special case to the heuristic of "let's not
> make a bug component for code components that are too small".  LLVM is
> factored to cleanly separate backend code, to the point where it's the one
> thing you can leave out at compile time; this can disincentivize people to
> care about bugs in backends that they don't use (and conversely backends
> seem like the most common/best supported out-of-tree use case). There's
> obviously a lot of variance in how actively-developed the backends are and
> how many people care about them, but it seems like if we care enough to
> have the code in-tree then maybe we care enough to have a bug component too.
>
>
>
> On Fri, Nov 9, 2018 at 10:45 AM Kristof Beyls via llvm-dev <
> llvm-dev at lists.llvm.org> wrote:
>
> Hi Zach,
>
>
>
> Thanks for elaborating.
>
> I like your proposal. I agree it still groups per area of expertise. And
> it makes the set of components we have easier to manage.
>
> Before making changes though I hope to hear opinions from others on this.
>
> What do others think?
>
>
>
> Thanks,
>
>
>
> Kristof
>
>
>
>
>
> On 9 Nov 2018, at 18:05, Zachary Turner <zturner at google.com> wrote:
>
>
>
> To elaborate, I didn't mean to group all components with less than 10 bugs
> into one massive component.  Rather, to do it separately for each
> subcomponent.  Grouping by expertise is fine, but I would argue that a
> component with 2 or 3 bugs filed per year is not a very useful component.
> There has to be some kind of bar for having a component otherwise you end
> up in the situation we have now.
>
>
>
> If you apply this algorithm to the existing set of components, you end up
> with something like this:
>
>
>
> Clang:
>
> * New Bugs
>
> * C++
>
> * Frontend
>
> * Formatter
>
> * LLVM Codegen
>
> * Static Analyzer
>
> * Driver
>
> * Modules
>
> * libclang
>
> * Other
>
>
>
> clang-tools
>
> * clang-tidy
>
> * Other
>
>
>
> compiler-rt
>
> * All Bugs
>
>
>
> Documentation
>
> * All Bugs
>
>
>
> libc++
>
> * All Bugs
>
>
>
> libraries
>
> * Backend:X86
>
> * Scalar Optimizations
>
> * Common Code Generator Code
>
> * Backend:AMDGPU
>
> * Loop Optimizer
>
> * Backend:WebAssembly
>
> * Backend:ARM
>
> * DebugInfo
>
> * Backend:AArch64
>
> * MC
>
> * GlobalISel
>
> * Core LLVM classes
>
> * Global Analyses
>
> * Interprocedural Optimizations
>
> * Support Libraries
>
> * Backend:PowerPC
>
> * Linker
>
> * Transformation Utilities
>
> * Other
>
>
>
> lld
>
> * ELF
>
> * COFF
>
> * Other
>
>
>
> lldb
>
> * All Bugs
>
>
>
> LNT
>
> * All Bugs
>
>
>
> new-bugs
>
> * All Bugs
>
>
>
> OpenMP
>
> * Clang Compiler Support
>
> * Runtime Support
>
>
>
> Packaging
>
> * All Bugs
>
>
>
> Phabricator
>
> * All Bugs
>
>
>
> Polly
>
> * All Bugs
>
>
>
> Runtime Libraries
>
> * libprofile
>
>
>
> Test Suite
>
> * All Bugs
>
>
>
> tools
>
> * All Bugs
>
>
>
> Website
>
> * All Bugs
>
>
>
> XRay
>
> * All Bugs
>
>
>
> I don't think it's helpful to have what essentially amounts to lots of
> dead components, because it causes confusion for bug reporters as well as
> triagers.  I also don't think the above split is radically different than
> what is already there, and for the most part, it still *is* organized by
> expertise.  It also means you need to find less volunteers to add
> themselves to the cc list for various components.  Instead of needing to
> find a separate volunteer for Hexagon, MSP430, PTX, RISC-V, Sparc, Bitcode
> Writer, and MCJIT, each of which has only 1 bug each (so in each case
> you're looking for a needle in a haystack to find the right person and get
> them to volunteer), you only need to find 1 for all of them, and there's a
> good chance that person will be at least somewhat familiar with backends in
> general and so know who the right person to talk to is in each case.
>
>
>
> Anyway, just my thoughts.
>
>
>
> On Fri, Nov 9, 2018 at 12:19 AM Kristof Beyls <Kristof.Beyls at arm.com>
> wrote:
>
> Hi Zach,
>
>
>
> Thanks for putting the data in a spreadsheet - that’s easier to navigate.
>
>
>
> And thanks for re-raising the question whether we have the right
> components in bugzilla.
>
> As I think this could be an area for lots of different opinions, without
> any near-perfect solution, it has the potential to be a discussion that
> drags on for a long time.
>
> I thought half of all bugs not getting triaged was a serious enough
> problem to try and tackle first (with this mail thread) before aiming to
> improve the component breakdown in bugzilla.
>
> I think that setting default-cc lists on the components we have currently
> is largely orthogonal to reducing/merging components, as we can always
> merge default-cc lists when we merge components.
>
>
>
>
>
> On actually coming up with a refined list of components: I think we’ll
> need to define/agree first on what guiding principles we follow when
> deciding something is worthwhile to be a separate component.
>
> Over the past few weeks I’ve heard a number of different options, ranging
> over:
>
>
>
>    - Just make a component for every sub-directory in the source code.
>    - Just make a component for every library that gets build in the LLVM
>    build.
>    - Make components so that each component has a significant enough
>    number of issues raised against it (I’m trying to paraphrase what you’re
>    proposing below).
>
>
>
> In my mind, the guiding principle should be:
>
>    - Components should reflect an area of expertise, so that each
>    component can have a set of recognised people that can triage and/or fix
>    bugs against that component.
>
>
>
> If we’d follow that principle, I think we should not merge all components
> with less than 10 bugs reported into an “Other” component.
>
> I do agree that some merging could still probably be done. E.g. maybe all
> the “clang/C++11”, “clang/C++14”, “clang/C++17”, “clang/C++2a” could be
> merged into a single component.
>
>
>
> So in summary:
>
>    - I don’t think we need to delay assigning
>    volunteers-for-triaging/default-cc lists to components. If we merge
>    components later on, we can merge cc lists, or asks the volunteers for the
>    relevant components If they want to remain on the default-cc list for the
>    merged component.
>    - My opinion is the we should define components based on areas of
>    expertise.
>
>
>
> Thanks,
>
>
>
> Kristof
>
>
>
> On 8 Nov 2018, at 20:39, Zachary Turner <zturner at google.com> wrote:
>
>
>
> Just so I'm clear, are we going to attempt to clean up and/or merge the
> components?  If we are, it makes sense to do that before we start putting
> ourselves as default CC's on the various components since they will just
> change.  If not, it would be nice to get some clarification on that now.
>
>
>
> I've put the above list into a spreadsheet so people can sort / filter it
> as they see fit.  The link is here:
>
>
>
>
> https://docs.google.com/spreadsheets/d/1aeU6P_vN2c63mpkilqni26U7XtEBDbzZYPFnovwr3FI/edit#gid=0
>
>
>
> I think a good starting point would be to get rid of any component with
> less than 10 bugs reported so far this year and merge them all into an
> "Other" component.
>
>
>
> On Thu, Nov 8, 2018 at 8:11 AM Kristof Beyls via cfe-dev <
> cfe-dev at lists.llvm.org> wrote:
>
> Hi,
>
>
>
> Yesterday, I’ve landed a description for how reported bugs should be
> flowing through the various stages of a bug’s life (triage, fixing,
> closing, …) at http://llvm.org/docs/BugLifeCycle.html.
>
> Thanks for the many many people who provided ideas and feedback for this!
>
>
>
> With there now being a description of what is expected during bug triaging
> (http://llvm.org/docs/BugLifeCycle.html#triaging-bugs), we're looking for
> more volunteers to actually do the bug triaging.
>
> About half of all raised bugs currently don’t seem to get triaged.
>
>
>
> The idea is to have one or more volunteers for each of the well over 100
> different product/component combinations we have in bugzilla.
>
> If you volunteer to help with triaging bugs against a specific component,
> we’ll add you to the default cc list for that component, so that when a new
> bug is raised against that component, you’ll get notified automatically
> through email. For components with few reported bugs, a single triager may
> suffice. For the high-traffic components, we’ll probably need multiple
> volunteers.
>
> I’ve provided the list of product/components below that had bugs reported
> against in 2018, together with how many bugs were reported against them
> this year so far, as an indication for which components may need more
> volunteers.
>
>
>
> I do want to highlight the “new-bugs/new bugs”, “clang/-New Bugs”
> components as those tend to be components people file bugs against if they
> don’t have a clue which part of clang/llvm is causing the issue they’re
> seeing. I believe that you don’t need to be an expert to be able to triage
> most of those bugs. If you want to learn more about llvm, volunteering to
> triage those bugs may be an interesting way to learn a lot more yourself.
>
>
>
> How can you get added to the default cc list/volunteer?
>
> * Preferred way: raise a bug against “Bugzilla Admin”/“Products” to get
> yourself added to the default cc list of the components of your choice.
>
> * Other way: email bugs-admin at lists.llvm.org
>
> * Yet another way: just reply to this mail.
>
>
>
> Thanks,
>
>
>
> Kristof
>
>
>
> new-bugs/new bugs: 535 bugs raised in 2018 (so far)
>
> clang/C++: 296 bugs raised in 2018 (so far)
>
> clang/-New Bugs: 260 bugs raised in 2018 (so far)
>
> libraries/Backend: X86: 202 bugs raised in 2018 (so far)
>
> libraries/Scalar Optimizations: 152 bugs raised in 2018 (so far)
>
> clang/Frontend: 120 bugs raised in 2018 (so far)
>
> lld/ELF: 120 bugs raised in 2018 (so far)
>
> clang/Formatter: 108 bugs raised in 2018 (so far)
>
> lldb/All Bugs: 102 bugs raised in 2018 (so far)
>
> clang/LLVM Codegen: 100 bugs raised in 2018 (so far)
>
> clang-tools-extra/clang-tidy: 87 bugs raised in 2018 (so far)
>
> clang/Static Analyzer: 84 bugs raised in 2018 (so far)
>
> libraries/Common Code Generator Code: 78 bugs raised in 2018 (so far)
>
> libc++/All Bugs: 67 bugs raised in 2018 (so far)
>
> lld/COFF: 64 bugs raised in 2018 (so far)
>
> libraries/Backend: AMDGPU: 60 bugs raised in 2018 (so far)
>
> libraries/Loop Optimizer: 44 bugs raised in 2018 (so far)
>
> lld/All Bugs: 30 bugs raised in 2018 (so far)
>
> clang/Driver: 30 bugs raised in 2018 (so far)
>
> Runtime Libraries/libprofile library: 29 bugs raised in 2018 (so far)
>
> libraries/Backend: WebAssembly: 27 bugs raised in 2018 (so far)
>
> libraries/Backend: ARM: 25 bugs raised in 2018 (so far)
>
> clang-tools-extra/Other: 25 bugs raised in 2018 (so far)
>
> libraries/DebugInfo: 25 bugs raised in 2018 (so far)
>
> OpenMP/Clang Compiler Support: 23 bugs raised in 2018 (so far)
>
> compiler-rt/compiler-rt: 21 bugs raised in 2018 (so far)
>
> libraries/Backend: AArch64: 19 bugs raised in 2018 (so far)
>
> clang/C++11: 19 bugs raised in 2018 (so far)
>
> libraries/MC: 18 bugs raised in 2018 (so far)
>
> Build scripts/cmake: 17 bugs raised in 2018 (so far)
>
> clang/Modules: 17 bugs raised in 2018 (so far)
>
> libraries/GlobalISel: 17 bugs raised in 2018 (so far)
>
> OpenMP/Runtime Library: 15 bugs raised in 2018 (so far)
>
> libraries/Global Analyses: 14 bugs raised in 2018 (so far)
>
> libraries/Core LLVM classes: 14 bugs raised in 2018 (so far)
>
> clang/libclang: 14 bugs raised in 2018 (so far)
>
> Documentation/General docs: 13 bugs raised in 2018 (so far)
>
> Packaging/deb packages: 13 bugs raised in 2018 (so far)
>
> libraries/Support Libraries: 13 bugs raised in 2018 (so far)
>
> libraries/Interprocedural Optimizations: 13 bugs raised in 2018 (so far)
>
> libraries/Backend: PowerPC: 11 bugs raised in 2018 (so far)
>
> libraries/Linker: 11 bugs raised in 2018 (so far)
>
> libraries/Transformation Utilities: 11 bugs raised in 2018 (so far)
>
> clang/C++14: 10 bugs raised in 2018 (so far)
>
> clang/Headers: 10 bugs raised in 2018 (so far)
>
> Test Suite/lit: 10 bugs raised in 2018 (so far)
>
> compiler-rt/profile: 10 bugs raised in 2018 (so far)
>
> tools/llvm-objdump: 9 bugs raised in 2018 (so far)
>
> tools/llvm-ar: 8 bugs raised in 2018 (so far)
>
> Polly/Other: 7 bugs raised in 2018 (so far)
>
> Polly/Optimizer: 7 bugs raised in 2018 (so far)
>
> libraries/Register Allocator: 7 bugs raised in 2018 (so far)
>
> tools/llc: 7 bugs raised in 2018 (so far)
>
> XRay/Runtime: 7 bugs raised in 2018 (so far)
>
> Packaging/Windows Installer: 6 bugs raised in 2018 (so far)
>
> Test Suite/Programs Tests: 6 bugs raised in 2018 (so far)
>
> clang/CUDA: 6 bugs raised in 2018 (so far)
>
> tools/lto: 6 bugs raised in 2018 (so far)
>
> compiler-rt/fuzzer: 6 bugs raised in 2018 (so far)
>
> compiler-rt/msan: 6 bugs raised in 2018 (so far)
>
> libraries/Backend: MIPS: 5 bugs raised in 2018 (so far)
>
> tools/opt: 5 bugs raised in 2018 (so far)
>
> Bugzilla Admin/Products: 5 bugs raised in 2018 (so far)
>
> clang/OpenCL: 5 bugs raised in 2018 (so far)
>
> libraries/Miscellaneous Instrumentation passes: 5 bugs raised in 2018 (so far)
>
> tools/llvm-dwarfdump: 5 bugs raised in 2018 (so far)
>
> compiler-rt/asan: 5 bugs raised in 2018 (so far)
>
> clang/Documentation: 4 bugs raised in 2018 (so far)
>
> libraries/OrcJIT: 4 bugs raised in 2018 (so far)
>
> tools/TableGen: 4 bugs raised in 2018 (so far)
>
> tools/bugpoint: 4 bugs raised in 2018 (so far)
>
> Phabricator/All Bugs: 4 bugs raised in 2018 (so far)
>
> XRay/Clang: 4 bugs raised in 2018 (so far)
>
> libraries/Backend: AVR: 4 bugs raised in 2018 (so far)
>
> Website/General Website: 3 bugs raised in 2018 (so far)
>
> lld/MachO: 3 bugs raised in 2018 (so far)
>
> libraries/Object: 3 bugs raised in 2018 (so far)
>
> tools/llvm-objcopy: 3 bugs raised in 2018 (so far)
>
> clang-tools-extra/Infrastructure: 3 bugs raised in 2018 (so far)
>
> tools/llvmc: 3 bugs raised in 2018 (so far)
>
> libraries/Target Description Classes: 3 bugs raised in 2018 (so far)
>
> tools/llvm-config: 3 bugs raised in 2018 (so far)
>
> libraries/LLVM assembly language parser: 3 bugs raised in 2018 (so far)
>
> compiler-rt/builtins: 2 bugs raised in 2018 (so far)
>
> libc++abi/All Bugs: 2 bugs raised in 2018 (so far)
>
> compiler-rt/lsan: 2 bugs raised in 2018 (so far)
>
> compiler-rt/ubsan: 2 bugs raised in 2018 (so far)
>
> LNT/LNT: 2 bugs raised in 2018 (so far)
>
> Polly/isl: 2 bugs raised in 2018 (so far)
>
> libraries/Interprocedural Analyses: 2 bugs raised in 2018 (so far)
>
> tools/analyze: 2 bugs raised in 2018 (so far)
>
> Runtime Libraries/other: 1 bugs raised in 2018 (so far)
>
> Packaging/binary tarballs: 1 bugs raised in 2018 (so far)
>
> libraries/Backend: Hexagon: 1 bugs raised in 2018 (so far)
>
> libraries/Bitcode Writer: 1 bugs raised in 2018 (so far)
>
> Bugzilla Admin/Mail: 1 bugs raised in 2018 (so far)
>
> libraries/MCJIT: 1 bugs raised in 2018 (so far)
>
> Documentation/Doxygen: 1 bugs raised in 2018 (so far)
>
> libraries/Backend: MSP430: 1 bugs raised in 2018 (so far)
>
> tools/opt-viewer: 1 bugs raised in 2018 (so far)
>
> libraries/Backend: RISC-V: 1 bugs raised in 2018 (so far)
>
> XRay/Tools: 1 bugs raised in 2018 (so far)
>
> clang-tools-extra/clang-query: 1 bugs raised in 2018 (so far)
>
> Website/Documentation: 1 bugs raised in 2018 (so far)
>
> compiler-rt/dfsan: 1 bugs raised in 2018 (so far)
>
> libraries/Backend: PTX: 1 bugs raised in 2018 (so far)
>
> libraries/Backend: Sparc: 1 bugs raised in 2018 (so far)
>
> compiler-rt/cfi: 1 bugs raised in 2018 (so far)
>
> compiler-rt/xray: 1 bugs raised in 2018 (so far)
>
>
>
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