Public bug reported:
Debugging why the Notes app would freeze for some people, I found there
were some stale .lock files around. Those .lock files are autocreated by
QSettings (with QLockFile) when this file is edited. Problem is, that it
sometimes seems to happen that the app is suspended by our lifecycle and
then killed (either by closing from spread or OOM killed) and those
.lock files stick around. I have implemented a workaround in the notes
app to clear up those stale locks when the app starts app, however,
today I ran twice in a row into the issue that the very same happened to
music app. It would just freeze on startup and never come back. Digging
around a bit I found such a stale lock file on its config file which is
created with the QML Settings element. This implies that every app using
QSettings or QML Settings {} are potentially affected. I suspect many
more app freezes can be traced down to this.
Now, there is some code in Qt to detect stale lock files, however, not
sure why it doesn't detect those lock files as stale ones and decides to
wait on them forever though.
** Affects: canonical-devices-system-image
Importance: Undecided
Status: New
** Affects: qtbase-opensource-src (Ubuntu)
Importance: Undecided
Status: New
** Project changed: canonical-devices-system-image => qtbase-opensource-
src (Ubuntu)
** Also affects: canonical-devices-system-image
Importance: Undecided
Status: New
** Description changed:
Debugging why the Notes app would freeze for some people, I found there
were some stale .lock files around. Those .lock files are autocreated by
- QSettings (with QLockFile) when this file is edited. Problems is, that
- it sometimes seems to happen that the app is suspended by our lifecycle
- and then killed (either by closing from spread or OOM killed) and those
+ QSettings (with QLockFile) when this file is edited. Problem is, that it
+ sometimes seems to happen that the app is suspended by our lifecycle and
+ then killed (either by closing from spread or OOM killed) and those
.lock files stick around. I have implemented a workaround in the notes
app to clear up those stale locks when the app starts app, however,
today I ran twice in a row into the issue that the very same happened to
music app. It would just freeze on startup and never come back. Digging
around a bit I found such a stale lock file on its config file which is
created with the QML Settings element. This implies that every app using
QSettings or QML Settings {} are potentially affected. I suspect many
more app freezes can be traced down to this.
Now, there is some code in Qt to detect stale lock files, however, not
sure why it doesn't detect those lock files as stale ones and decides to
wait on them forever though.
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https://bugs.launchpad.net/bugs/1576989
Title:
stale lock files freeze apps
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