Followup-For: Bug #862558
Dear maintainer,
I plan to NMU plasma-workspace if the release team approves the attached patch.
(Unblock request #864067)
Best regards,
Nobuhiro
2017-05-31 23:38 GMT+09:00 YOSHINO Yoshihito <yy.y.ja.jp@gmail.com>:
> Followup-For: Bug #862558
> Control: reassign -1 plasma-workspace
> Control: affects -1 uim-qt5 uim-mozc
> Control: tags -1 + patch
>
> Dear Maintainer,
>
> This is a bug in ksplashqml. An upstream commit
> https://cgit.kde.org/plasma-workspace.git/commit/?id=56d2c15b9acb9c4b57398b281685807c3191f622
> has caused this problem.
>
> x-session-manag,133,kdetest /usr/bin/x-session-manager
> ├─(ksplashqml,232)
> ├─ssh-agent,191 /usr/bin/im-launch x-session-manager
> ├─uim-toolbar,220
> │ ├─{llvmpipe-0},235
> │ ├─{llvmpipe-1},236
> │ ├─{llvmpipe-2},237
> │ └─{llvmpipe-3},238
> └─uim-xim,219
> ksplashqml,233,kdetest Breeze --pid
> ├─mozc_server,239
> │ ├─{IPCServer},244
> │ ├─{QueueTimer},240
> │ ├─{QueueTimer},243
> │ └─{WatchDog},242
> ├─uim-candwin-qt5,245 -v
> │ ├─{QDBusConnection},249
> │ └─{QXcbEventReader},248
> ├─{QDBusConnection},255
> ├─{QQmlThread},254
> ├─{QXcbEventReader},234
> ├─{llvmpipe-0},250
> ├─{llvmpipe-1},251
> ├─{llvmpipe-2},252
> └─{llvmpipe-3},253
>
> # strace -f -p 133
> strace: Process 133 attached
> read(3, ^Cstrace: Process 133 detached
> <detached ...>
>
> It looks like the parent process (133), x-session-manager (startkde
> script), is waiting for the stdout of the ksplashqml process (232),
> but which is now defunct. Its child process(es) may be writing to the
> same fd.
>
> # ls -l /proc/133/fd/3
> lr-x------ 1 kdetest kdetest 64 May 31 05:13 /proc/133/fd/3 -> pipe:[88694]
>
> The direct child of the ksplashqml process (233), the splash screen daemon,
> closes the file descriptor at ksplash/ksplashqml/main.cpp:97.
>
> # ls -l /proc/233/fd/1
> ls: cannot access '/proc/233/fd/1': No such file or directory
>
> One of the children of the process (239), mozc_server, is holding the fd:
>
> # ls -l /proc/239/fd/1
> l-wx------ 1 kdetest kdetest 64 May 31 05:14 /proc/239/fd/1 -> pipe:[88694]
>
> So the startkde process has finished reading the pid number string from
> the now-defunct process, but is still waiting for another write(s) until
> the (shared) fd has been closed.
>
> This mozc_server process has been started during uim-qt5
> (a QPlatformInputContext) startup in the SplashApp
> initialization phase at ksplash/ksplashqml/main.cpp:92.
>
> Due to the upstream commit the splash screen daemon does not close file
> descriptors before the SplashApp initialization, thus its subprocess
> shares the fds.
>
> The commit log states Wayland initialization of this daemon needs the
> channels. While it may require open file descriptors 0, 1 or 2,
> no one should expect the process to talk to the parent through the
> descriptors, since the splash screen is a daemon.
>
> An attached patch reverts the commit and redirects the file descriptors
> to /dev/null.
>
> Regards,
> --
> YOSHINO Yoshihito <yy.y.ja.jp@gmail.com>
--
Nobuhiro Iwamatsu
iwamatsu at {nigauri.org / debian.org}
GPG ID: 40AD1FA6
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