Can't run servo headlessly in Xvfb

[shinglyu]

Step to reproduce

I follow @larsbergstrom 's instruction to start my Xvfb this way:

Xvfb :10 -screen 0 1280x960x24 +extension RANDR +extension RENDER +extension GLX

Then I run servo in another shell

export DISPLAY=:10
./servo -z -x -o output.png about:blank                                                            

but it crashes and produce the error messages below

P.S. I copied the servo binary and resources folder instead of using ./mach run, because I want to run tests on a specific Servo version in my CI system.

Environment

Servo version: 074c7e8
OS: Linux slyu-workstation 3.13.0-68-generic #111-Ubuntu SMP Fri Nov 6 18:17:06 UTC 2015 x86_64 x86_64 x86_64 GNU/Linux (Linux Mint)

Logs

Servo:

./servo/servo -z -x -o output.png about:blank                                                            
Xlib:  extension "XFree86-VidModeExtension" missing on display ":10.0".
Xlib:  extension "GLX" missing on display ":10.0".
Xlib:  extension "GLX" missing on display ":10.0".
[1]    5098 segmentation fault (core dumped)  ./servo/servo -z -x -o output.png about:blank

Xvfb:

Initializing built-in extension Generic Event Extension
Initializing built-in extension SHAPE
Initializing built-in extension MIT-SHM
Initializing built-in extension XInputExtension
Initializing built-in extension XTEST
Initializing built-in extension BIG-REQUESTS
Initializing built-in extension SYNC
Initializing built-in extension XKEYBOARD
Initializing built-in extension XC-MISC
Initializing built-in extension SECURITY
Initializing built-in extension XINERAMA
Initializing built-in extension XFIXES
Initializing built-in extension RENDER
Initializing built-in extension RANDR
Initializing built-in extension COMPOSITE
Initializing built-in extension DAMAGE
Initializing built-in extension MIT-SCREEN-SAVER
Initializing built-in extension DOUBLE-BUFFER
Initializing built-in extension RECORD
Initializing built-in extension DPMS
Initializing built-in extension Present
Initializing built-in extension DRI3
Initializing built-in extension X-Resource
Initializing built-in extension XVideo
Initializing built-in extension XVideo-MotionCompensation
Initializing built-in extension SELinux
Initializing built-in extension GLX
[dix] Could not init font path element /usr/share/fonts/X11/cyrillic, removing from list!
[dix] Could not init font path element /usr/share/fonts/X11/100dpi/:unscaled, removing from list!
[dix] Could not init font path element /usr/share/fonts/X11/75dpi/:unscaled, removing from list!
[dix] Could not init font path element /usr/share/fonts/X11/100dpi, removing from list!
[dix] Could not init font path element /usr/share/fonts/X11/75dpi, removing from list!
6 XSELINUXs still allocated at reset
SCREEN: 0 objects of 256 bytes = 0 total bytes 0 private allocs
DEVICE: 0 objects of 96 bytes = 0 total bytes 0 private allocs
CLIENT: 0 objects of 144 bytes = 0 total bytes 0 private allocs
WINDOW: 0 objects of 48 bytes = 0 total bytes 0 private allocs
PIXMAP: 1 objects of 16 bytes = 16 total bytes 0 private allocs
GC: 4 objects of 16 bytes = 64 total bytes 0 private allocs
CURSOR: 1 objects of 8 bytes = 8 total bytes 0 private allocs
TOTAL: 6 objects, 88 bytes, 0 allocs
1 PIXMAPs still allocated at reset
PIXMAP: 1 objects of 16 bytes = 16 total bytes 0 private allocs
GC: 4 objects of 16 bytes = 64 total bytes 0 private allocs
CURSOR: 1 objects of 8 bytes = 8 total bytes 0 private allocs
TOTAL: 6 objects, 88 bytes, 0 allocs
4 GCs still allocated at reset
GC: 4 objects of 16 bytes = 64 total bytes 0 private allocs
CURSOR: 1 objects of 8 bytes = 8 total bytes 0 private allocs
TOTAL: 5 objects, 72 bytes, 0 allocs
1 CURSORs still allocated at reset
CURSOR: 1 objects of 8 bytes = 8 total bytes 0 private allocs
TOTAL: 1 objects, 8 bytes, 0 allocs
1 CURSOR_BITSs still allocated at reset
TOTAL: 0 objects, 0 bytes, 0 allocs
[dix] Could not init font path element /usr/share/fonts/X11/cyrillic, removing from list!
[dix] Could not init font path element /usr/share/fonts/X11/100dpi/:unscaled, removing from list!
[dix] Could not init font path element /usr/share/fonts/X11/75dpi/:unscaled, removing from list!
[dix] Could not init font path element /usr/share/fonts/X11/100dpi, removing from list!
[dix] Could not init font path element /usr/share/fonts/X11/75dpi, removing from list!

[shinglyu]

If I run it using ./mach run -r -z -x -o output.png about:blank, there is not error.
I can observe the servo process showed up for a while in top. But after it disappear, the ./mach command doesn't exit, and there is no output of any kind.

[larsbergstrom]

Just to confirm, do you have all of the relevant mesa packages installed? The list we have on our buildbot instances is here:
https://github.com/servo/saltfs/blob/master/servo-build-dependencies/init.sls#L15-L25

I'm not able to reproduce this problem locally, but my machine is configured identically to the Linux buildbots.

[shinglyu]

I installed all the mesa packages but no luck.

I saw there was a build option for headless, but was removed in https://github.com/servo/servo/pull/8641/files#diff-4b02cf15724590179b4a5025f1a81a0dL379 , is that related?

I'll try it in a Ubuntu 14.04 VM, probably my Linux Mint modified some Ubuntu graphics stuff.

[shinglyu]

In a Ubuntu 14.04 VM, the GLX missing error was gone, but I still get this:

vagrant@vagrant-ubuntu-trusty-64:~/MozITP/test/servo$ ./servo -z -x -o output.png about:blank                                    
Xlib:  extension "XFree86-VidModeExtension" missing on display ":10".
Segmentation fault (core dumped)

I'll try to run it using saltfs's servo-master1 setup.

[aneeshusa]

@shinglyu Heads up, servo-linux1 is probably a better choice because it will already have our xvfb setup installed (which is also kept in the saltfs repo, see the xvfb folder).

[shinglyu]

@aneeshusa Thanks. I found that out before I leave the office. Now my office machine is running servo-linux1 and building Servo in it. By the way, where will the servo root directory be in servo-linux1? I believe the Git() step will clone it, but I'm not sure where it will place it. All the other steps just use ./mach build ... without cd so I guess there is a convention for where it should be placed?

[aneeshusa]

@shinglyu This is in the servo-linux1 Vagrant VM, not the actual servo-linux1.servo.org machine, right?

You don't need to use Buildbot at all to build Servo; you can just git clone the repo anywhere, cd into it, and ./mach build ... from there, so there's no special place for the servo root directory. I believe you may have to increase the memory given to Vagrant to build Servo successfully though - just increase the 1024 number in the Vagrantfile.

On our actual builders, I believe Buildbot will use /home/servo/buildbot/slave/${builder_name}/build directories, where builder_name is one of linux-rel, mac-dev-unit, etc.

[larsbergstrom]

@shinglyu Can you also try on a page other than about:blank? That error (about XFree86-VidModeExtension) is also printed in successful runs with Xvfb. I haven't looked into it yet.

[shinglyu]

I tested in servo-linux1 Vagrant VM (locally, of course). It works, and it prints the XFree86-VidModeExtension too, so it's not the problem.

I tried about:blank and https://www.wikipedia.org, both works.

So I believe there is some difference between Linux Mint and its base Ubuntu version. I'll close this and use the VM to run my tests.

Thanks @larsbergstrom and @aneeshusa !