[Libguestfs] [ovirt-devel] virt-v2v become zombie via python cpopen on error

[Shahar Havivi]

On 30.03.16 14:28, Nir Soffer wrote:
> On Wed, Mar 30, 2016 at 1:36 PM, Michal Skrivanek
> <michal.skrivanek at redhat.com> wrote:
> >
> >> On 30 Mar 2016, at 11:49, Richard W.M. Jones <rjones at redhat.com> wrote:
> >>
> >> On Wed, Mar 30, 2016 at 12:19:35PM +0300, Shahar Havivi wrote:
> >>> Hi,
> >>>
> >>> We encounter a problem in VDSM project that virt-v2v become zombie task while
> >>> importing vm from vmware.
> >>> When virt-v2v is in 'copy disk' mode and we someone deletes the vm at vmware
> >>> the process hang in read() method,
> >>> I am pretty sure that its not virt-v2v problem because when I run it from the
> >>> shell virt-v2v exit with an error, still maybe someone have an idea....
> >>>
> >>> I wrote a small python script that encounter the problem:
> >>>
> >>> ----------------------------------------------------------------------------
> >>> from cpopen import CPopen
> >>>
> >>> env = {'LIBGUESTFS_BACKEND': 'direct'}
> >>> cmd = ['/usr/bin/virt-v2v', '-ic',
> >>>       'vpx://....', '-o',
> >>>       'local', '-os', '/tmp', '-of', 'raw', '-oa', 'sparse',
> >>>       '--password-file', '/tmp/passwd', '--machine-readable', 'bbb']
> >>> p = CPopen(cmd, env=env)
> >>> while p.returncode is None:
> 
> p.returncode just return the instance variable, there is no wait() involved.
> 
> The right way:
> 
>     while p.poll() is None:
the problem is proc.stdout.read(1) didn't raise and error when the stream
closed but return ''.
its a CPopen behaviour and works differently in subprocess.

>         ...
> 
> p.returncode calling wait is non-standard feature in vdsm AsyncProc
> wrapper. This is
> the object used by v2v vdsm module, so there accessing p.returncode does call
> p.poll().
> 
> These non-standard apis will be removed from vdsm, please do not use them.
> 
> >>>    c = p.stdout.read(1)
> >>>    print c
> >>> ----------------------------------------------------------------------------
> >>
> >> An actual zombie task?  That would indicate that the parent process
> >> (your Python program) wasn't doing a wait system call.
> >>
> >> I downloaded the cpopen-1.4 program, and it doesn't appear to call any
> >> of the wait*(2) system calls anywhere, so that could be the problem.
> >
> > I suppose the cpopen parameters are not alright…I’m sure vdsm developers can help with that.
> >
> >>
> >> Rich.
> >>
> >> --
> >> Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
> >> Read my programming and virtualization blog: http://rwmj.wordpress.com
> >> virt-p2v converts physical machines to virtual machines.  Boot with a
> >> live CD or over the network (PXE) and turn machines into KVM guests.
> >> http://libguestfs.org/virt-v2v
> >
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