[Bug 1457639] Re: qemu-img qcow2 conversion hangs on large core systems

[Serge Hallyn]

** Changed in: qemu (Ubuntu Vivid)
       Status: In Progress => Won't Fix

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https://bugs.launchpad.net/bugs/1457639

Title:
  qemu-img qcow2 conversion hangs on large core systems

Status in Ubuntu Cloud Archive:
  New
Status in qemu package in Ubuntu:
  Fix Released
Status in qemu source package in Vivid:
  Won't Fix
Status in qemu source package in Wily:
  Fix Released

Bug description:
  [Impact]
  qemu-img frequently hangs when converting a file to qcow2 on a system with a large number of cores.

  [Test Case]
  On a system with a large number of cores (my test system has 48), run:

  wget http://cloud-images.ubuntu.com/trusty/current/trusty-server-cloudimg-arm64-disk1.img -O disk.img
  for i in $(seq 1 10); do qemu-img convert -O qcow2 disk.img disk.qcow2; done

  Mine always hangs within the first 3 iterations.

  [Regression Risk]
  Fix is a clean cherry pick from upstream, which should give us a clear path to resolution if regressions are found.

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