Comment 6 for bug 512850

I also see this problem: Dragging & dropping from the library causes Mixxx's GUI to hang forever (though the currently-playing deck still continues.) Apparently dragging and dropping confuses the reader (or deadlocks something.) Here's me right-clicking and choosing Load in Player 1 (same if I just double-click):

Debug: [Main]: Running Mixxx
Debug: [Main]: TrackDAO::getTrack QThread(0x2b08400, name = "Main") "qt_sql_default_connection"
Debug: [Main]: TrackInfoObject: emitting bpmUpdated signal!
Debug: [Main]: setCuePoints 0
Debug: [AnalyserQueue 1]: AnalyserWaveform: f 44100 samplesPerDownsample: 110 downsamples 410050 from 45105408
Debug: [Main]: Received waveform from track

That's a normal load. Now I drag & drop the same track to Player 1:

Debug: [Main]: TrackDAO::getTrack QThread(0x2b08400, name = "Main") "qt_sql_default_connection"
Debug: [Main]: TrackDAO::updateTrackInDatabase QThread(0x2b08400, name = "Main") "qt_sql_default_connection"
Debug: [Main]: Updating track "Whitney Houston, I'm Your Baby Tonight" in database...
Debug: [Reader 1]: Couldn't load track with filename: ""
Debug: [AnalyserQueue 1]: AnalyserWaveform :: Waveform downsampling finished.
Debug: [AnalyserQueue 1]: AnalyserWaveform :: Generation took 16.218 seconds

So far, no freeze, but it's been set up. (That Debug: [Reader 1]: Couldn't load track with filename: "" looks suspicious since I don't see that on a successful load.) Now I double-click the same track:

Debug: [Main]: TrackDAO::getTrack QThread(0x2b08400, name = "Main") "qt_sql_default_connection"
Debug: [Main]: TrackInfoObject: emitting bpmUpdated signal!
Debug: [Main]: setCuePoints 0
Debug: [Main]: TrackDAO::updateTrackInDatabase QThread(0x2b08400, name = "Main") "qt_sql_default_connection"
Debug: [Main]: Updating track "" in database...

...and she's frozen. (The GUI at least.)