Mixxx 2.3 partially stalles on Ubuntu Focal 20.04 LTS

[mixxxbot]

Reported by: daschuer
Date: 2021-01-07T11:11:32Z
Status: New
Importance: Undecided
Launchpad Issue: lp1910529

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I have revived an old machine with Intel(R) Core(TM)2 Quad CPU Q6600 @ 2.40GHz running Ubuntu Ubuntu Focal 20.04 LTS.

Several Times during testing different 2.3 PRs I have experienced a strange stalled situation.

The library does not scroll any more, the slider do not react, but the waveform is still moving and the sound is playing, I can scratch the track and tooltips are also available.

Unfortunately I have not yet found a recipe to reproduce the issue.

Today it happens during navigating the library without any track playing.

Mixxx was build with Debug mode, but started without any parameter.

Debug [Main]: WTrackTableView::loadTrackModel() PlaylistTableModel(0x5581f0554b90)
Debug [Main]: PlaylistTableModel(0x5581f0554b90) select() took 0 ms 9
Debug [Main]: TrackCollectionManager - Saving track "/home/daniel/Musik/2010/Esther & Abi Ofarim - Cinderella Rockefella.mp3" in internal collection
Debug [Main]: BeatFactory::loadBeatsFromByteArray could not parse serialized beats.
Debug [Main]: BaseTrackCache(0x5581f7390db0) updateIndexWithQuery took 0 ms
Debug [Main]: Committing transaction on "MIXXX-1" result: true

[mixxxbot]

Commented by: daschuer
Date: 2021-01-07T11:21:51Z

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It happens again. I can even move the slider, but the screen is not refreshed.

[mixxxbot]

Commented by: daschuer
Date: 2021-01-07T11:31:03Z

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Mixxx 2.2.3 is also affected.

Using x11 + Unity + GeForce 8600 GT/PCIe/SSE2 Nvidia Driver 340.108

[mixxxbot]

Commented by: Be-ing
Date: 2021-01-07T12:45:20Z

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If it happens with 2.2 then I do not think we should hold back 2.3 for this. Does it happen with 2.1.8 with Qt4?

Have you tried disabling spinnies and using different waveform renderers? What about hiding level meters?

While it's good to support old hardware, we have to draw the line somewhere for what we will support. I think it's fine to not support a desktop CPU from 14 years ago. Is anyone actually trying to use such a machine to DJ?

[mixxxbot]

Commented by: daschuer
Date: 2021-01-20T11:34:36Z

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By now this happens only with Unity on Focal.
Since I have switched to the Ubuntu Desktop (Gnome + X11) the issue has not happened again.

Keylock with RubberBand might be involved.
Or a too long audio processing.