[Bug 1923648] Re: macOS App Nap feature gradually freezes QEMU process

[Thomas Huth]

Moved here:
https://gitlab.com/qemu-project/qemu/-/issues/334

** Bug watch added: gitlab.com/qemu-project/qemu/-/issues #334
   https://gitlab.com/qemu-project/qemu/-/issues/334

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https://bugs.launchpad.net/bugs/1923648

Title:
  macOS App Nap feature gradually freezes QEMU process

Status in QEMU:
  Fix Released

Bug description:
  macOS version: 10.15.2
  QEMU versions: 5.2.0 (from MacPorts)
                 5.2.92 (v6.0.0-rc2-23-g9692c7b037)

  If the QEMU window is not visible (hidden, minimized or another
  application is in full screen mode), the QEMU process gradually
  freezes: it still runs, but the VM does not respond to external
  requests such as Telnet or SSH until the QEMU window is visible on the
  desktop.

  This behavior is due to the work of the macOS App Nap function:
  
https://developer.apple.com/library/archive/documentation/Performance/Conceptual/power_efficiency_guidelines_osx/AppNap.html#//apple_ref/doc/uid/TP40013929-CH2-SW1

  It doesn't matter how the process is started -- as a background job or
  as a foreground shell process in case QEMU has a desktop window.

  My VM does not have a display output, only a serial line, most likely
  if the VM was using OpenGL, or playing sound (or any other App Nap
  triggers), then the problem would never have been detected.

  In my case only one starting way without this problem:
  sudo qemu-system-x86_64 -nodefaults \
  -cpu host -accel hvf -smp 1 -m 384 \
  -device virtio-blk-pci,drive=flash0 \
  -drive 
file=/vios-adventerprisek9-m.vmdk.SPA.156-1.T.vmdk,if=none,format=vmdk,id=flash0
 \
  -device e1000,netdev=local -netdev 
tap,id=local,ifname=tap0,script=no,downscript=no \
  -serial stdio -display none

  The typical way from the internet to disable App Nap doesn't work:
  defaults write NSGlobalDomain NSAppSleepDisabled -bool YES

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