QLockFile won't notice if the lock pid is re-used by an unrelated process

[Michael Terry]

My desktop webbrowser-app instance no longer seems to be remembering the previous session tabs and opening them at startup.

I don't see any output on the console. Any tips for helping debug this?

[Olivier Tilloy (osomon)]

There is a top-level setting that you can switch on/off to remember the last browsing session. Maybe it was turned off (it is on by default)?

If not, it could be that the serialized session file is corrupted, deleting $HOME/.local/share/webbrowser-app/session.json should help (before you do that, can you make a backup copy, and if it doesn’t contain any sensitive information send it my way for further investigation?).

[Michael Terry (mterry)]

After some digging, this is a bug in QLockFile. It doesn't take process name into account. So if the pid for the session.json lockfile is re-used (easy to do after a reboot), it will act like the session file is still valid.

Qt trunk fixes this (http://code.qt.io/cgit/qt/qtbase.git/tree/src/corelib/io/qlockfile_unix.cpp?h=dev). So it's just a matter of updating Qt (or backporting the patch).

[Michael Terry (mterry)]

https://bugreports.qt.io/browse/QTBUG-45497

Fixed upstream in Qt 5.5

[Michael Terry (mterry)]

I've added canonical-devices-system-image, since this bug has a real effect on the phone -- sometimes the browser will fail to restore its last session.

[Michael Terry (mterry)]

Here's a version of the upstream patch, modified to apply against wily's version of Qt.

[kevin gunn (kgunn72)]

@Mirv - just assigning to you for patch landing, since i figure you might have more than one to land, if it doesn't make sense, just ping us on irc

[Timo Jyrinki (timo-jyrinki)]

Starting landing.

[Timo Jyrinki (timo-jyrinki)]

Vivid: https://launchpad.net/~ci-train-ppa-service/+archive/ubuntu/landing-041/
Wily: https://launchpad.net/~ci-train-ppa-service/+archive/ubuntu/landing-051/ (still building, ETA 2h)

Please test.

Final OTA-7 freeze is today so this won't land to it unless specifically targeted to that milestone, or if this silo is put into QA queue already today.

[Timo Jyrinki (timo-jyrinki)]

qtbase-opensource-src (5.4.1+dfsg-2ubuntu10) vivid; urgency=medium

  * debian/patches/stale-process-lock.patch:
    - Fix QLockFile not noticing if the lock pid is re-used by unrelated
      process (LP: #1500444)

 -- Timo Jyrinki <email address hidden> Tue, 29 Sep 2015 05:11:51 +0000

[Launchpad Janitor (janitor)]

This bug was fixed in the package qtbase-opensource-src - 5.4.2+dfsg-2ubuntu6

---------------
qtbase-opensource-src (5.4.2+dfsg-2ubuntu6) wily; urgency=medium

  * debian/patches/stale-process-lock.patch:
    - Fix QLockFile not noticing if the lock pid is re-used by unrelated
      process (LP: #1500444)

 -- Timo Jyrinki <email address hidden> Tue, 29 Sep 2015 07:18:23 +0000