[pdfPlugin] Multithreading does not work properly on ARM SoC

Bug #1432412 reported by Stefano Verzegnassi on 2015-03-15
This bug affects 1 person
Affects Status Importance Assigned to Milestone
Ubuntu Document Viewer App

Bug Description

While loading a PDF document, the number of image providers is set based on the value returned by QThread::idealThreadCount()[1].
On the latest ARM architectures, some of the cores of a SoC may be temporarily turned off, in order to improved the power consumption.
This may cause a wrong number of initialized image providers (e.g. only 2 image providers on a quad-core CPU).

[1]: http://doc.qt.io/qt-4.8/qthread.html#idealThreadCount

Related branches

Changed in ubuntu-docviewer-app:
importance: High → Critical
Changed in ubuntu-docviewer-app:
assignee: nobody → Stefano Verzegnassi (verzegnassi-stefano)
status: Triaged → In Progress
Changed in ubuntu-docviewer-app:
milestone: none → 2015-04-02

Fix committed into lp:ubuntu-docviewer-app at revision 107, scheduled for release in ubuntu-docviewer-app, milestone 2014-10-30

Changed in ubuntu-docviewer-app:
status: In Progress → Fix Committed

Alan Pope's comment during the review of lp:~verzegnassi-stefano/ubuntu-docviewer-app/workaround-fix-1432412 branch:

"Tested on bq device and works fine. We may need to re-visit on meizu device (which runs vivid, and a newer kernel) because it seems to never spin more than 1 core even under heavy load in this app."

I re-mark this report as "triaged", so we can track any progress/discussion about the meizu issue.

Changed in ubuntu-docviewer-app:
status: Fix Committed → Triaged
importance: Critical → Medium
assignee: Stefano Verzegnassi (verzegnassi-stefano) → nobody
Changed in ubuntu-docviewer-app:
milestone: 2015-04-02 → none
Changed in ubuntu-docviewer-app:
milestone: none → ota-11
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