Important Qt 5.6.0 notes

[Weng Xuetian]

Since I wrote the other two patches mentioned there, l'd clarify what is 
affected by the later two patches. I'm not forcing anyone to apply it, because 
they haven't got enough review yet. It is possible that they have some unknown 
bad side-effect. The only thing that I can say is that they works well for me.

For https://codereview.qt-project.org/#/c/151496/  (https://bugreports.qt.io/
browse/QTBUG-51648)

The bug affects at least kde-telepathy (actually kauth too, but it has 
workaround in 5.20 so no need to worry about that right now) and will leaves 
some deadlock process (ktp-proxy). In the worst scenario, if you keep using 
ktp and open chat window many times, the deadlock process would end up using 
all your memory.

https://codereview.qt-project.org/#/c/151340/

This one is more important on system that systemd starts user session dbus. 
(can be checked with $ systemctl --user status dbus.service ), otherwise some 
processes might deadlock on reboot or shutdown and leads to very long shutdown 
(a stop job is still running for session c2).

On Wednesday, 16 March 2016 13:48:35 PDT David Edmundson wrote:
> Qt 5.6.0 has a few noticable regressions since a DBus change, this causes a
> problem where kded may deadblock breaking functionality in Plasma and
> potentially any frameworks based application.
> 
> Before shipping Qt 5.6.0 *please* apply the following patch:
> https://codereview.qt-project.org/#/c/151459/
> <https://codereview.qt-project.org/#/c/151459/>without it, Plasma may
> completely fail to load.
> 
> The Qt DBus maintainer also recommends that distros backport this:
> http://lists.qt-project.org/pipermail/development/2016-March/025272.html
> 
> 
> I would also like to see:
> https://codereview.qt-project.org/#/c/151496/
> https://codereview.qt-project.org/#/c/151340/
> 
> included, but they are less important.
> 
> David