[cfe-dev] [llvm-dev] [RFC] LLVM bug lifecycle BoF - triaging

Simon Pilgrim via cfe-dev cfe-dev at lists.llvm.org
Sun Oct 14 05:17:10 PDT 2018

Kristof + Paul, thank you for organising this BoF!

A cleanup of the components would be welcome, we have multiple 
components that get used as dumping grounds (new bugs, clang/new bugs, 
clang/llvm codegen for instance), just merging those into a single "new 
bugs"/"unconfirmed" component would at least mean bugs are in the same 

We have components for things that don't exist any more (old backends 
....), and we are missing components for some major parts of the 
codebase (various tools, should vectorizers be put in a single 
component? etc.) - it's all scope for bugs getting filed, lost and 

Embedding more information in the bugzilla main page as well - for 
instance we barely use keywords (including the beginner tag which still 
holds promise), adding keyword links (or just the 
https://bugs.llvm.org/describekeywords.cgi table) to the bottom of the 
main page could be trivial.

We're also including links to godbolt (sorry, Compiler Explorer) pages a 
lot more in bugs, there are probably things we can do to make that more 
integral to the reporting/triage process - I keep wondering if there'd 
be ways to make that part of web-based reduction and bisection processes.

Finally, finding ways to properly triage the oss-fuzz reports that get 
sent to [llvm-bugs] - their signal:noise is poor (fuzz tests....) and I 
have the feeling that most of those go completely unchecked and many 
'fixes' are by pure chance.


On 10/10/2018 19:17, via llvm-dev wrote:
> A couple of additional data points to consider…
> Approximately 30% of all reported bugs are still open.
> The number of open bugs grows by roughly 28 per week. This has been 
> consistent for the past 6 years, when I started tracking it.  I've 
> reported this to the mailing list a few times as an FYI.
> So, we do okay—70% of bugs get closed even though we have no defined 
> process—but clearly we can do better.
> Personally I think anything that raises bug-awareness in the community 
> can only help.  All of the ideas so far have sounded great. Replacing 
> the "new bugs" category with UNCONFIRMED or something like that should 
> be good; making sure that everything at least gets looked at is 
> important. Looking forward to the BoF.
> --paulr
> *From:*Alex Rønne Petersen [mailto:alex at alexrp.com]
> *Sent:* Saturday, October 06, 2018 5:50 PM
> *To:* Kristof.Beyls at arm.com
> *Cc:* llvm-dev at lists.llvm.org; cfe-dev at lists.llvm.org; 
> lldb-dev at lists.llvm.org; tanyalattner at llvm.org; nd at arm.com; Robinson, Paul
> *Subject:* Re: [cfe-dev] [RFC] LLVM bug lifecycle BoF - triaging
> Hello,
> I am not a frequent poster on the LLVM mailing lists, but I happened 
> to notice this thread and thought I'd weigh in.
> Over 2 years ago, I reported this bug: 
> https://bugs.llvm.org/show_bug.cgi?id=29102 
> <https://bugs.llvm.org/show_bug.cgi?id=29102>
> We had to add a pretty ugly workaround in Mono to deal with that, and 
> the workaround is still to this day written to apply to *all* Clang 
> versions on ARM64 because we've gotten no response to the bug. This is 
> what we're doing currently: 
> https://github.com/mono/mono/blob/master/mono/utils/atomic.h#L209
> I think this looks to be a pretty serious bug that shouldn't have gone 
> unacknowledged for so long. If there had been any kind of response to 
> the bug, I would've even been happy to cook up a patch. But, frankly, 
> without any confirmation that a bug is valid, very few potential 
> contributors are going to put in the time and effort to write and 
> submit a patch and risk that it gets rejected because the issue it's 
> trying to address isn't even considered a bug by the project maintainers.
> Don't get me wrong, though - I understand from experience that "triage 
> all the bugs" is much easier said than done, especially in an open 
> source project. I just wanted to back up Kristof's feeling that the 
> project is losing potential contributions with a concrete example of 
> such, for what it's worth.
> Regards,
> Alex
> On Thu, Oct 4, 2018 at 11:55 AM Kristof Beyls via cfe-dev 
> <cfe-dev at lists.llvm.org <mailto:cfe-dev at lists.llvm.org>> wrote:
>     Hi all,
>     I’d like to share a few thoughts and analysis results on the LLVM
>     bug life cycle, especially the reporting/triaging part.
>     As one of the few people creating llvm bugzilla accounts when
>     people request an account, I started to have a feel that many
>     reported bugs, especially by first-time reporters, never get any
>     reply or feedback, let alone be acted on.
>     If people go through the effort of requesting an account, and then
>     reporting the bug, they show motivation to contribute to the
>     project. However, if then they see zero return on their effort
>     spent, even if it’s just a confirmation of the bug indeed being
>     real or an explanation of what they thought to be a bug isn’t
>     actually a bug, I fear as a community we disincentify a large
>     number of potential long-term contributors.
>     The above was all based on gut feel, so I tried to gather a bit
>     more data to see if my feel was correct or not.
>     I scraped the bugs in bugzilla and post-processed them a bit.
>     Below is a chart showing, year by year, how long it takes for a
>     reported bug to get any comment from anyone besides to original
>     reporter. If the bug is still open and didn’t have any reaction
>     after half a year the chart categorizes is as an “infinite”
>     response time.
>     It shows that in recent years the chance of never getting a
>     response to a bug report has been increasing.
>     For some bugs - e.g. an experienced LLVM developer records a
>     not-that-important bug in bugzilla - that may be just fine.
>     However, I assume that for people reporting a bug for the first
>     time, the majority may look at least for confirmation that what
>     they reported is actually a bug.
>     The chart shows (blue bars) that about 50% of first-time bug
>     reporters never get any reply.
>     I also plotted which components get the most reported bugs that
>     don’t get any reaction and remain open:
>     The percentage at the top of the bars is the percentage of bugs
>     against that component that never get any reaction. The bar height
>     shows the absolute numbers.
>     I hope that at the “Lifecycle of LLVM bug reports” BoF at the
>     upcoming dev meeting in San Jose
>     (https://llvmdev18.sched.com/event/H2T3, 17th of October,
>     10.30am), we can discuss what could be done to improve the
>     experience for first-time reporters and also to reduce the number
>     of bug reports that seemingly get ignored completely.
>     By sending this email, I hope to trigger discussion before the
>     BoF, both by attendees and non-attendees, so that we have a more
>     fruitful outcome.
>     At first sight, to me, it seems that the following actions would help:
>       * Let’s introduce some form of “triaged” state in bugzilla, to
>         represent that a bug report has been accepted as describing a
>         real problem; able to be acted on (e.g. has a suitable
>         reproducer); and not being a duplicate of another bug report.
>         Looking at
>         https://bugzilla.readthedocs.io/en/5.0/using/editing.html#life-cycle-of-a-bug,
>         maybe the best way to achieve this would be for newly raised
>         bugs to by default go to an “UNCONFIRMED” state instead of
>         “NEW”? Moving the status to “NEW” or “CONFIRMED” would
>         indicate the bug has been triaged.
>       * Would it help to have one or multiple people per component
>         that volunteer to triage new bugs?
>       * With the majority of developers being part of a team working
>         on a product based on LLVM, I would assume that it is in the
>         interest of most that reported bugs at least get
>         evaluated/triaged? What is stopping those developers to find
>         the time to do some triaging? Would a better notification
>         mechanism be useful to notify when new bugs on a specific
>         component come in that you could triage? Maybe per component
>         try to have a few people on the “default CC list”, which seems
>         easy to set up as a bugzilla administrator.
>       * Should we get rid of the "new-bugs/new bugs” component if we
>         won’t have people triaging them?
>       * Should we have some description of what a reasonable triage of
>         a bug looks like? If we write such a page, we could also use
>         that page to describe what we think should get recorded when
>         closing bugs.
>     Thanks,
>     Kristof
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