Bug 252126

Version:           1.4.0 (using KDE 4.5.1) 
OS:                Linux

I've tried both QMYSQL and QSQLITE, and they both share the following problem:

On the first KDE bootup I have desktop effects active, the splash screen gently fades into the desktop background, and with either QMYSQL or QSQLITE things look ok (akonadi is running, tables are generated, etc.). Now, wait a minute or so and log out, and then, log back in.  Now what happens is that as the splash screen begins to fade, the screen goes briefly very dark sometimes, other times not so dark (for 1/2- 1 sec), and then the desktop wallpaper appears immediately after. If I log out, and then back in, same thing -- on every re-login. If I then logout (to kdm), switch to vt1, remove the akonadi-generated databases, switch back to vt8, login, then all is perfect just like the very first login. Logging out, and then back in, same problem occurs.

This is definitely not a video/driver problem. In particular, if I disable akonadi: the problem never occurs. 

Looking at the akonadi code, I see that a number of methods us QProcess::waitForStarted(), QProcess::waitForFinished(), and QIODevice::waitForBytesWritten(), and/or QIODevice::waitForReadyRead(). My understanding is that these are blocking functions which should not be used in a GUI context. My theory is that somehow they are blocking the thread which is doing the screen painting following login. To test this I simply inserted a delay in server/src/storage/dbinitializer.cpp:

 83 bool DbInitializer::run()
 84 {
 85   sleep(4);
 86   qDebug() << "DbInitializer::run()";
 87 

Now, this is not a proposed fix or anything (rather silly actually), but I wanted see if I delayed akaonadi doing the db checking/updating, it would help. Sure enough, the issue is gone -- get a nice smooth login everytime. Now doing this, probably will cause problems on logout. The reason why it doesn't ever happen on the very first login, I assume is due to an effective delay internal to akonadi: it has to generate the databases, and then only after that do any checking/updating. For all logins after the first, it can jump right in to doing the db table checking/updating, resulting in the blocking. Just speculating here of course. 

Anyway, Can this be looked into ? Is there a way of doing the above QProcess/QIODevice functions in separate thread ?

thanks much for your time,
John

Reproducible: Always

Steps to Reproduce:
see above 

Actual Results:  
see above

Expected Results:  
a gradual fade in of the desktop background