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[Bug 1480877] Re: Access points' "PropertiesChanged" dbus signals freeze UI on mobile devices


Here's a new version of the patch with all the access-point related
signals removed.

It makes no sense for any of this logic to be present in our system, as
none of our code attempts to control the network configuration via
Bearer Mgmt.  With this patch, the plugin will never receive any NM
access-point related signals, and therefore it'll never populate it's
access point list.

Also, as pointed out in other comments, the bearer plugin includes
blocking DBus calls that are made in response to every single
'PropertiesChanged' signal sent for an access point, which causes a
ripple of DBus traffic every time a scan occurs.

@Lorn, if you could look over my patch, I'd appreciate it.

It'd be also nice to get some testing from @faenil and @mterry before we
push forward with landing plans.    I've confirmed that the CPU spikes
in the dbus daemon go away completely with the changes.  That said, it'd
be good to get some independent results.

Until we have a silo prep'd for Qt, you can just install the
libqt5network5_5.4.1+dfsg-2ubuntu10~awe16_armhf.deb from my PPA:


You also probably want to install dbus-cpp and location-services from:


The status of the location-service silo says it needs a rebuild, but the
packages in the PPA should be OK for testing.  If you have any
questions, ask before you install anything.

** Patch added: "New version of QtBase network bearer plugin"

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  Access points' "PropertiesChanged" dbus signals freeze UI on mobile

Status in Canonical System Image:
Status in Unity 8:
Status in dbus-cpp package in Ubuntu:
  In Progress
Status in indicator-network package in Ubuntu:
Status in network-manager package in Ubuntu:
Status in qtbase-opensource-src package in Ubuntu:
  In Progress
Status in buteo-syncfw package in Ubuntu RTM:
Status in location-service package in Ubuntu RTM:
  In Progress
Status in maliit-framework package in Ubuntu RTM:
Status in network-manager package in Ubuntu RTM:
Status in sync-monitor package in Ubuntu RTM:

Bug description:
  Krillin, rc-proposed, r83

  I've been trying to track down the cause of the occasional UI freezes on my Krillin device, and I noticed that whenever the UI freezes for 2-4 seconds, I get a burst of "PropertiesChanged" signals in dbus-monitor

  Here's a log of what's shown in dbus-monitor:

  I'd guess the problem is in the code that actually catches the signals
  and acts accordingly.

  1) Move to a place where many wifi hotspots are available
  2) Connect the device via USB and run "phablet-shell" and then "dbus-monitor"
  3) Use the device while keeping an eye on dbus-monitor output

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