unity8 freezes randomly

[Jean-Baptiste Lallement]

krillin #205

[Sorry for the poor description]

On krillin UI freeze randomly. For example on the screenshot it occurred while dragging the greeter to unlock the phone. I was playing music, woke up the phone with the power button to turn the display on and did a right edge swipe to remove the greeter.

This has been reported by several people in the past days, but I didn't find a pattern to reproduce this bug reliably.

There is no crash in /var/crash and no apport activity.
If I press the power button to turn the screen off/on again, the greeter is completely displayed (ie. doesn't cover half of the screen like the screenshot) but the UI is not responsive to gestures or input events. A long press on the power button shows the shutdown dialog but none of the button can be pressed.

top doesn't show any specific process going crazy

ProblemType: Bug
DistroRelease: Ubuntu 14.10
Package: unity8 8.00+14.10.20140822-0ubuntu1
Uname: Linux 3.4.67 armv7l
ApportVersion: 2.14.6-0ubuntu2
Architecture: armhf
Date: Sat Aug 23 14:18:00 2014
InstallationDate: Installed on 2014-08-23 (0 days ago)
InstallationMedia: Ubuntu Utopic Unicorn (development branch) - armhf (20140823-020205)
SourcePackage: unity8
UpgradeStatus: No upgrade log present (probably fresh install)

[Jean-Baptiste Lallement (jibel)]

strace of unity8 when the system is in this "frozen" state

[Jean-Baptiste Lallement (jibel)]

it happened again 2 minutes ago, still while playing music and trying to unlock the screen.

[Michał Sawicz (saviq)]

When this happens again for you, please go to the phone and, as root, go:
$ gdb program `pidof unity8`
gdb> set logging on
gdb> t a a bt
gdb> quit

Please upload the resulting gdb.txt.

[Daniel d'Andrada (dandrader)]

Seems related to bug 1295623.

[Daniel d'Andrada (dandrader)]

Yeah, same as bug 1295623. When you have pin-lock security enabled you cannot drag in the launcher or indicators per design. Thus the slightly different symptoms.

[Jean-Baptiste Lallement (jibel)]

This is not a duplicate, when it happens the UI is completely frozen, no indicator and no launcher even with the dash visible. In the screenshot attached the greeter even stopped in the middle of the transition.

[Alexander Sack (asac)]

reproduced hang. followed gdb instructions; this didn't produce a gdb.txt; here what i got on console:

adb shell
root@ubuntu-phablet:/# gdb program `pidof unity8`
GNU gdb (Ubuntu 7.8-0ubuntu1) 7.8
Copyright (C) 2014 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law. Type "show copying"
and "show warranty" for details.
This GDB was configured as "arm-linux-gnueabihf".
Type "show configuration" for configuration details.
For bug reporting instructions, please see:
<http://www.gnu.org/software/gdb/bugs/>.
Find the GDB manual and other documentation resources online at:
<http://www.gnu.org/software/gdb/documentation/>.
For help, type "help".
Type "apropos word" to search for commands related to "word"...
program: No such file or directory.
Attaching to process 6503
Reading symbols from /usr/bin/unity8...(no debugging symbols found)...done.
Reading symbols from /usr/lib/arm-linux-gnueabihf/libQt5Gui.so.5...(no debugging symbols found)...done.
Loaded symbols for /usr/lib/arm-linux-gnueabihf/libQt5Gui.so.5
Reading symbols from /usr/lib/arm-linux-gnueabihf/libQt5Qml.so.5...(no debugging symbols found)...done.
Loaded symbols for /usr/lib/arm-linux-gnueabihf/libQt5Qml.so.5
Reading symbols from /usr/lib/arm-linux-gnueabihf/libQt5Quick.so.5...(no debugging symbols found)...done.
Loaded symbols for /usr/lib/arm-linux-gnueabihf/libQt5Quick.so.5
Reading symbols from /usr/lib/arm-linux-gnueabihf/libQt5Network.so.5...(no debugging symbols found)...done.
Loaded symbols for /usr/lib/arm-linux-gnueabihf/libQt5Network.so.5
Reading symbols from /usr/lib/arm-linux-gnueabihf/libQt5Core.so.5...(no debugging symbols found)...done.
Loaded symbols for /usr/lib/arm-linux-gnueabihf/libQt5Core.so.5
Reading symbols from /usr/lib/arm-linux-gnueabihf/libstdc++.so.6...(no debugging symbols found)...done.
Loaded symbols for /usr/lib/arm-linux-gnueabihf/libstdc++.so.6
Reading symbols from /lib/arm-linux-gnueabihf/libgcc_s.so.1...(no debugging symbols found)...done.
Loaded symbols for /lib/arm-linux-gnueabihf/libgcc_s.so.1
Reading symbols from /lib/arm-linux-gnueabihf/libc.so.6...(no debugging symbols found)...done.
Loaded symbols for /lib/arm-linux-gnueabihf/libc.so.6
Reading symbols from /lib/ld-linux-armhf.so.3...(no debugging symbols found)...done.
Loaded symbols for /lib/ld-linux-armhf.so.3
Reading symbols from /lib/arm-linux-gnueabihf/libpng12.so.0...(no debugging symbols found)...done.
Loaded symbols for /lib/arm-linux-gnueabihf/libpng12.so.0
Reading symbols from /usr/lib/arm-linux-gnueabihf/libharfbuzz.so.0...(no debugging symbols found)...done.
Loaded symbols for /usr/lib/arm-linux-gnueabihf/libharfbuzz.so.0
Reading symbols from /lib/arm-linux-gnueabihf/libz.so.1...(no debugging symbols found)...done.
Loaded symbols for /lib/arm-linux-gnueabihf/libz.so.1
Reading symbols from /usr/lib/arm-linux-gnueabihf/libhybris-egl/libGLESv2.so.2...(no debugging symbols found)...done.
Loaded symbols for /usr/lib/arm-linux-gnueabihf/libhybris-egl/libGLESv2.so.2
Reading symbols from /lib/arm-linux-gnueabihf/li...

[Alexander Sack (asac)]

ok, had to cd to /tmp so its writable... attached the gdb.txt file; seems its the same then what i posted inline before.

[Jean-Baptiste Lallement (jibel)]

it happened which the switcher was active, it suddenly froze.

[Jean-Baptiste Lallement (jibel)]

s/which/while/

[Michał Sawicz (saviq)]

Right, so we don't have a deadlock here, rather a missing input issue. Has this been happening to you again recently? This feels related to bug #1295623 where input gets confused, I'd like to land the fix for that (should be this week) and see if this issue is still a problem.

[Jean-Baptiste Lallement (jibel)]

It didn't happen recently. Each time indicator or edges were responsive so 1295623 it was. I'm leaving this one to incomplete for the moment and if it doesn't occur again, I'll close it.

[Chris Gagnon (chris.gagnon)]

I just had this happen again in RTM image 20140916

[Chris Gagnon (chris.gagnon)]

The cpu is pegged on qmlscene
phablet@ubuntu-phablet:~$ top -n1 -b
top - 19:17:07 up 1:57, 1 user, load average: 0.00, 0.01, 0.05
Tasks: 236 total, 1 running, 215 sleeping, 20 stopped, 0 zombie
%Cpu(s): 25.1 us, 30.5 sy, 0.0 ni, 43.1 id, 1.3 wa, 0.0 hi, 0.0 si, 0.0 st
KiB Mem: 983788 total, 911036 used, 72752 free, 20360 buffers
KiB Swap: 524284 total, 360248 used, 164036 free. 146268 cached Mem

  PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
32043 phablet 20 0 364460 31836 21464 S 91.1 3.2 71:46.72 qmlscene
11505 phablet 20 0 6088 1112 796 R 16.1 0.1 0:00.06 top
 1941 root 20 0 238252 5780 4140 S 10.7 0.6 4:34.14 unity-syst+
28727 phablet 20 0 417516 64080 32800 S 5.4 6.5 6:57.64 unity8
    1 root 20 0 3860 2056 1004 S 0.0 0.2 0:15.02 init

[service]
base: system-image.ubuntu.com
http_port: 80
https_port: 443
channel: ubuntu-touch/ubuntu-rtm/14.09-proposed
device: krillin
build_number: 44
version_detail: ubuntu=20140916,device=20140912-23825b8,custom=1410739265,version=44

[Chris Gagnon (chris.gagnon)]

The start up screen for the dialer app is being displayed, but the qmlscene process that is pegging the cpu is the music app.

ls -la /proc/<pid>/cwd shows

cwd -> /usr/share/click/preinstalled/com.ubuntu.music/1.3.625

[Chris Gagnon (chris.gagnon)]

I had this happen again on image 44

phablet@ubuntu-phablet:~$ cat /etc/system-image/channel.ini
[service]
base: system-image.ubuntu.com
http_port: 80
https_port: 443
channel: ubuntu-touch/ubuntu-rtm/14.09-proposed
device: krillin
build_number: 44
version_detail: ubuntu=20140916,device=20140912-23825b8,custom=1410739265,version=44

This time the cpu was not being pegged qmlscene or anything else.

[Chris Gagnon (chris.gagnon)]

there are no crash files.

[Chris Gagnon (chris.gagnon)]

re-assigned to kgunn as saviq is on holiday.

[Jean-Baptiste Lallement (jibel)]

It happened again today, while switching between apps.

[Jean-Baptiste Lallement (jibel)]

on krillin 14.09 #1

[Jean-Baptiste Lallement (jibel)]

after several minutes, the dash resumed without any intervention from me, no crash, and unity8 didn't restart. It's now fully operational without rebooting the phone.

[Jean-Baptiste Lallement (jibel)]

and again, this time by switching between the scopes (picture attached)

[Jean-Baptiste Lallement (jibel)]

When this happens there is the following message displayed in unity8-dash.log

virtual com::ubuntu::location::service::session::Interface::Ptr com::ubuntu::location::service::Stub::create_session_for_criteria(const com::ubuntu::location::Criteria&): org.freedesktop.DBus.Error.NoReply: Did not receive a reply. Possible causes include: the remote application did not send a reply, the message bus security policy blocked the reply, the reply timeout expired, or the network connection was broken.
virtual com::ubuntu::location::service::session::Interface::Ptr com::ubuntu::location::service::Stub::create_session_for_criteria(const com::ubuntu::location::Criteria&): org.freedesktop.DBus.Error.NoReply: Did not receive a reply. Possible causes include: the remote application did not send a reply, the message bus security policy blocked the reply, the reply timeout expired, or the network connection was broken.

[kevin gunn (kgunn72)]

updating target date, we thot this was a dup of the good ol' input bug.

working on this with priority, just being realistic about the target date 2014-10-02

[Michael Terry (mterry)]

So between comments 29 and 31, it *looks* like the in-process location-service proxy for scopes provided by unity-scopes-shell is making a synchronous request to the location service. This causes the dash to "freeze" waiting for the dbus call to time out.

While this happens, because communication between the dash and the unity8 shell are also synchronous, we end up freezing unity8 too.

There are fixes in flight for both, although only the first issue needs to be fixed to consider this bug fixed.

https://code.launchpad.net/~unity-api-team/unity-scopes-shell/location-service-on-background-thread/+merge/235174
https://code.launchpad.net/~mzanetti/unity8/async-dashcommunicator/+merge/235272

*Hopefully* once that first branch lands (it's in silo now), we can see if this is reproducable still.

[Michael Terry (mterry)]

(Arguably this is a dup of bug 1370524 then.)

Here's the silo for testing, for the impatient: https://launchpad.net/~ci-train-ppa-service/+archive/ubuntu/landing-014

[kevin gunn (kgunn72)]

I'm going to go ahead and mark this as a dupe of bug 1370524
open a fresh bug if witnessed after bug 1370524 is closed or you can verify it's not due to the location service

[Chris Gagnon (chris.gagnon)]

remarking as a dupe and opening a fresh bug