Mixxx with 4 decks unusable on 2017 retina macbook pro

Bug #1810099 reported by RJ Skerry-Ryan on 2018-12-30
This bug affects 2 people
Affects Status Importance Assigned to Milestone

Bug Description

Mixxx is unusable on a 15" retina Macbook Pro 2017 with Core i7 2.8 gHz processor with 4 decks playing.

2 decks work reasonably well, thanks to the improvements in
but 4 decks pushes Mixxx into some kind of livelock state, where rendering the GUI cannot keep up with the engine.

RJ Skerry-Ryan (rryan) wrote :

By unusable, I mean there are multiple seconds of GUI lag for any action (clicking play, scratching a waveform, etc.).

Changed in mixxx:
status: New → Confirmed
importance: Undecided → Critical
milestone: none → 2.3.0
RJ Skerry-Ryan (rryan) wrote :

Lots of hypotheses about potential root causes for this, I'll add some more comments and a video to better demonstrate the symptoms.

Be (be.ing) wrote :

Can you reproduce this with --safeMode? Which macOS SDK do you build with?

RJ Skerry-Ryan (rryan) wrote :

10.13 SDK on macOS 10.13.6 built via Homebrew, not using the official build environments. But the 2.2.0 release binary has this problem too.

Can't reproduce with --safeMode, though FPS 60 does cause some lag (100-200ms) when seeking with WOverview even with --safeMode, since the VU meters are being rendered at 60 FPS by the VsyncThread.

jus (jus) wrote :

Same on macOS 10.14.2 (18C54) with latest master
Macbook pro 2018 with automatic graphics switching
Qt 5.12.0 via homebrew
OpenGL: 4.1

*3 fps when idle
*8 fps when idle with spinnies, and preview button disabled
*12 fps when idle with ``--safemode``

waveformUpdateTick() emitted several hundred times per second??

Worth noticing that, when starting wit ``safemode`` , the integrated graphics is used , while when starting normal, discrete graphics is used

Be (be.ing) wrote :

Is this from side effect from moving to Qt 5? Was performance better with 2.1?

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