# Travis woes: warning accessibility bus and segmentation fault
**URL:** https://discourse.julialang.org/t/travis-woes-warning-accessibility-bus-and-segmentation-fault/9362
**Category:** General Usage
**Tags:** question, travis
**Created:** [February 27, 2018, 10:05am UTC](https://discourse.julialang.org/t/travis-woes-warning-accessibility-bus-and-segmentation-fault/9362 "2018-02-27T10:05:07Z")
**Posts on this page:** 10
**Page:** 1
### Author:  [@yakir12](https://discourse.julialang.org/u/yakir12)
#### Post date: [February 27, 2018, 10:05am UTC](https://discourse.julialang.org/t/travis-woes-warning-accessibility-bus-and-segmentation-fault/9362/1 "2018-02-27T10:05:07Z")
Hi CI wizards,
I’m having some trouble with Travis and was wondering if someone could lend me some wisdom.
I’m getting a few of these warnings:
```julia
**(julia:6922): WARNING**: Error retrieving accessibility bus address: org.freedesktop.DBus.Error.ServiceUnknown: The name org.a11y.Bus was not provided by any .service files
```
and then a segmentation fault right when the test calls a function that plots a few frames to a `gif` file using the `GR` backend. Ironically, I would get segmentation faults on _my_ machine if I used the `PyPlot` backend… So really confused here on what’s causing it.
```julia
signal (11): Segmentation fault
while loading /home/travis/.julia/v0.6/TrackRoots/test/runtests.jl, in expression starting on line 44
__longjmp_chk at /lib/x86_64-linux-gnu/libc.so.6 (unknown line)
⋮
```
It occurs in [this](https://github.com/yakir12/TrackRoots.jl) package, which uses: Cairo, DataDeps, Images, ImageMagick, ImageFeatures, Unitful, Distances, UnitfulAngles, OffsetArrays, StaticArrays, Distributions, ImageFiltering, FileIO, Gtk, ImageView, Colors, GtkReactive, FixedPointNumbers, Plots, GR, and HDF5.
Any ideas how I can fix this?
[Here](https://justpaste.it/1hnuy) is the Travis log report (or [here](https://api.travis-ci.org/v3/job/346691033/log.txt)).
---
### Author:  [@yakir12](https://discourse.julialang.org/u/yakir12)
#### Post date: [February 27, 2018, 10:35am UTC](https://discourse.julialang.org/t/travis-woes-warning-accessibility-bus-and-segmentation-fault/9362/2 "2018-02-27T10:35:49Z")
In an attempt to trouble shoot this, I tried a mock test where I just plot 3 random frames into a `gif` file and test if the file was created. I got an error `could not spawn ffmpeg`! Which is weird since I thought that would be one of the dependencies of `Plots.jl`…? I’ll try and add that to the ~~`.travis.yml` file~~.
---
### Author:  [@yakir12](https://discourse.julialang.org/u/yakir12)
#### Post date: [February 27, 2018, 10:53am UTC](https://discourse.julialang.org/t/travis-woes-warning-accessibility-bus-and-segmentation-fault/9362/3 "2018-02-27T10:53:15Z")
I don’t know (yet) if these issues are related, but `Plots.jl` does not have a declared dependency on `ffmpeg` so any test involving `gif`s fails on Travis. I reported the [issue](https://github.com/JuliaPlots/Plots.jl/issues/1415).
---
### Author:  [@yakir12](https://discourse.julialang.org/u/yakir12)
#### Post date: [February 27, 2018, 2:31pm UTC](https://discourse.julialang.org/t/travis-woes-warning-accessibility-bus-and-segmentation-fault/9362/4 "2018-02-27T14:31:12Z")
OK, the latest is that `Plots.jl` would rather stay light and restrain from adding more dependencies. So I’ve asked
> [@How to add ffmpeg to Travis?](https://discourse.julialang.org/t/how-to-add-ffmpeg-to-travis/9366):
>
> In order to test Plots.jl’ gif creation in Travis, i.e. something like this: using Base.Test, Plots anim = @animate for i=1:2 plot(rand(2)) end name = tempname()\*".gif" gif(anim, name) @test isfile(name) we have to somehow add ffmpeg as a dependency (e.g. in the .travis.yml file, or via BinDeps.jl). Does anyone know exactly how this is done?
To see how others have solved this problem.
The answer to this question, I suspect, is that I need to add `ffmpeg` as a dependency to my Travis instance.
---
### Author:  [@yakir12](https://discourse.julialang.org/u/yakir12)
#### Post date: [February 27, 2018, 7:41pm UTC](https://discourse.julialang.org/t/travis-woes-warning-accessibility-bus-and-segmentation-fault/9362/5 "2018-02-27T19:41:02Z")
I thought that the lack of `ffmpeg` on Travis caused all the warnings and segmentation fault, but I was wrong: after successfully adding `ffmpeg` to Travis the warnings and segmentation fault were still there. [Here](https://api.travis-ci.org/v3/job/346833767/log.txt)’s the log of my most recent tests.
Following @Tamas_Papp’s advice on commenting out the plotting parts to see if it helps I found out that:
1. The [warning: error retrieving accessibility bus address](https://travis-ci.org/yakir12/TrackRoots.jl/jobs/346937761#L1204) is still there
2. The segmentation fault is gone
So now I have no idea what causes those warnings, but the segmentation occurs in the plotting part. I’ll continue to comments out parts of the plotting in an attempt to pin point where the fault occurs.
---
### Author:  [@yakir12](https://discourse.julialang.org/u/yakir12)
#### Post date: [February 27, 2018, 9:36pm UTC](https://discourse.julialang.org/t/travis-woes-warning-accessibility-bus-and-segmentation-fault/9362/6 "2018-02-27T21:36:20Z")
Right. I tested a very minimal plot (see [here](https://github.com/yakir12/TrackRoots.jl/blob/master/src/saving.jl#L56-L69)) and it still resulted in a segmentation fault (see [here](https://travis-ci.org/yakir12/TrackRoots.jl/jobs/346966756#L1275)), following a myriad of warnings about “retrieving accessibility bus address” (see [here](https://travis-ci.org/yakir12/TrackRoots.jl/jobs/346966756#L1205)).
I think my next step will be to try and separate between the GUI component and all the rest. Hopefully by removing all the GUI out of this module (and perhaps putting it in a submodule) the plotting will work…
---
### Author:  [@Ralph\_Smith](https://discourse.julialang.org/u/Ralph_Smith)
#### Post date: [February 28, 2018, 3:45am UTC](https://discourse.julialang.org/t/travis-woes-warning-accessibility-bus-and-segmentation-fault/9362/7 "2018-02-28T03:45:38Z")
Don’t know if it will help your real issue, but the accessibility bus problem may be alleviated by installing the `at-spi2-core` Ubuntu package.
---
### Author:  [@yakir12](https://discourse.julialang.org/u/yakir12)
#### Post date: [February 28, 2018, 9:40am UTC](https://discourse.julialang.org/t/travis-woes-warning-accessibility-bus-and-segmentation-fault/9362/8 "2018-02-28T09:40:10Z")
Thanks @Ralph_Smith
> [@Ralph\_Smith](#):
>
> installing the at-spi2-core Ubuntu package
helped get rid of the bus warnings, so that’s great! Unfortunately the segmentation fault is still [there](https://travis-ci.org/yakir12/TrackRoots.jl/jobs/347181421#L1265)…
I’ll try to separate the plots from the GUI now, see how that might help.
---
### Author:  [@yakir12](https://discourse.julialang.org/u/yakir12)
#### Post date: [February 28, 2018, 10:12am UTC](https://discourse.julialang.org/t/travis-woes-warning-accessibility-bus-and-segmentation-fault/9362/9 "2018-02-28T10:12:04Z")
In an unexpected twist of cruel fate, the windows appveyor cleared that last run. This should have been impossible, because:
1. The run before this one failed on Windows
2. The addition of `at-spi2-core` should have only affected Linux
Yea, I’m not sure what is going on here, but I’ll just trudge on and pretend there is no spoon.
---
### Author:  [@yakir12](https://discourse.julialang.org/u/yakir12)
#### Post date: [March 1, 2018, 1:15pm UTC](https://discourse.julialang.org/t/travis-woes-warning-accessibility-bus-and-segmentation-fault/9362/10 "2018-03-01T13:15:42Z")
Day 3. So I separated the GUI from the package completely. Still fragmentation fault. So it wasn’t the GUI. It’s the plots, specifically the `Plots.frame`. Not sure how to proceed now. Of course appveyor claims it’s all good.