Bug 337366

Since upgrading to 4.13 I am experiencing lockup problems using akonadi's sqlite backend. At a random point after starting akonadi / kontact, akonadi gets stuck when syncing folders or retrieving mails. The process list in kontact (status bar lower right side) shows something like "syncing folder XXX %Y" but it stays at Y%. At that point a cannot access any mails, calendar items, or contacts. 

Running akonadi from console I get a debug message:
  "[QSQLITE3: 140502062065408] " sqlite3_blocking_step: Entering while loop

Searching for this on the Internet I'll find among other things a commit message removing the code to print this message: http://permalink.gmane.org/gmane.comp.kde.cvs/1316401 (message date Apr. 6 2014 - Enable concurrency in our copy of QSQLITE driver) and other links pointing to older(?) versions (ie. 1.3.90) of akonadi where the code seems to active. After restarting akonadi (`akonadictl stop`, wait until akonadi server exits which takes a 20 seconds or so and then `akonadictl start`) everything works find for a while - sometimes a could of hours up to a day.

I found a similar bug report from Nov. 2012 which might be related but in my case everything works fine until a certain point (not gettings stuck in init). Also, I am able to normal close the applications and stop akonadi (which takes some time though): https://bugs.kde.org/show_bug.cgi?id=310652

Maybe of interest: I have to IMAP accounts set-up and two DavCal Groupware resources (a total of 3 address books + 1 calendar / 1 task imported from the first resource, and 6 calendars / 6 tasks imported from the second source).

Platform: opensuse 13.1 using the KDE stable build service

Software versions:
akonadi-4.13.2-10.1.x86_64
plasma-addons-akonadi-4.13.2-4.1.x86_64
python-kde4-akonadi-4.13.2-4.2.x86_64
libakonadiprotocolinternals1-1.12.1-3.1.x86_64
akonadi-runtime-1.12.1-3.1.x86_64
libakonadi4-4.13.2-4.1.x86_64
kontact-4.13.2-10.1.x86_64
kmail-4.13.2-10.1.x86_64


PS: I cannot simply switch to other backends as I am running akonadi / kontact on a thin client set-up (SunRays) host multiple users and starting a database server on such a system wouldn't be my first choice.

Reproducible: Always

Steps to Reproduce:
1. start akonadi and kontact
2. work normally and wait
Actual Results:  
At some point (hours up to a day) akonadi / kontact gets stuck when trying to sync IMAP folders / mails.

Expected Results:  
Folders / Mails will be synced