5:53 p.m.
Hi!
I am running into interesting problem with UUID. I am using Ruby
bindings, but I think the
problem is not specific to Ruby. I am doing roughly the following:
dom = c.define_domain_xml(xml)
dom1 = c.ookup_domain_by_uuid(dom.uuid)
and I got an error that domain with given UUID is not found.
If I print UUID of newly defined domain and compare it with output
of 'dominfo' command in virsh I can see that it differs.
Could anybody shed some light on why UUID returned by
define_domain_xml()
is invalid?
Sincerely,
Vadim
--
"La perfection est atteinte non quand il ne reste rien a ajouter, mais
quand il ne reste rien a enlever." (Antoine de Saint-Exupery)
5:09 a.m.
On Sat, Mar 29, 2008 at 03:53:22PM -0700, Vadim Zaliva wrote:
I am running into interesting problem with UUID. I am using Ruby
bindings,
but I think the
problem is not specific to Ruby. I am doing roughly the following:
dom = c.define_domain_xml(xml)
dom1 = c.ookup_domain_by_uuid(dom.uuid)
and I got an error that domain with given UUID is not found.
If I print UUID of newly defined domain and compare it with output
of 'dominfo' command in virsh I can see that it differs.
Could anybody shed some light on why UUID returned by define_domain_xml()
is invalid?
That's quite strange. Is this Xen? What does the XML look like?
Rich.
--
Richard Jones, Emerging Technologies, Red Hat http://et.redhat.com/~rjones
virt-top is 'top' for virtual machines. Tiny program with many
powerful monitoring features, net stats, disk stats, logging, etc.
http://et.redhat.com/~rjones/virt-top
11:14 a.m.
On Mar 31, 2008, at 3:09, Richard W.M. Jones wrote:
That's quite strange. Is this Xen? What does the XML look like?
Yes, this is XEN 3.2. XML is attached.
Vadim
--
"La perfection est atteinte non quand il ne reste rien a ajouter, mais
quand il ne reste rien a enlever." (Antoine de Saint-Exupery)
11:46 a.m.
On Sat, 2008-03-29 at 15:53 -0700, Vadim Zaliva wrote:
I am running into interesting problem with UUID. I am using Ruby
bindings, but I think the
problem is not specific to Ruby. I am doing roughly the following:
dom = c.define_domain_xml(xml)
dom1 = c.ookup_domain_by_uuid(dom.uuid)
and I got an error that domain with given UUID is not found.
Very strange .. I just tried the same, albeit with the KVM backend, and
it works fine. The two UUID's are the same, both if the XML used to
define it has an explicit UUID, and if it is assigned in the backend.
I don't have a Xen host set up right now, so it's probably a silly
question: Does Xen assign UUID's when domains are defined, or only once
a domain is created ?
David
1:40 p.m.
On Mar 31, 2008, at 3:09, Richard W.M. Jones wrote:
That's quite strange. Is this Xen? What does the XML look like?
I am trying to track down the problem. One thing I see is that if I
define/undefine
twice, returned UUID is the same. Does not it have some random
component in it (I see
some random stuff in uuid.c)?
Here is roughly what I am seeing right now:
D, [11:29:06#15021] DEBUG -- : xdefine_domain_xml(xml)
D, [11:29:06#15021] DEBUG -- : New domain defined with UUID
6911f001-6991-bc1c-e455-11f6f99e3951
D, [11:29:06#15021] DEBUG -- : undefine(6911f001-6991-bc1c-
e455-11f6f99e3951)
Then, the second attempt, within same process, second later:
D, [11:29:33#15021] DEBUG -- : define_domain_xml(xml)
D, [11:29:33#15021] DEBUG -- : New domain defined with UUID
6911f001-6991-bc1c-e455-11f6f99e3951
D, [11:29:34#15021] DEBUG -- : undefine(6911f001-6991-bc1c-
e455-11f6f99e3951)
E, [11:29:34#15021] ERROR -- : unknown error - libvir call
virDomainLookupByUUID failed (SystemCallError)
after the second attempt, because 'undefine' failed, I can see still
defined domain in virsh:
virsh # dominfo sample-domain
Id: -
Name: sample-domain
UUID: ccdbf043-cf3d-902b-f08f-1d6a0d571f13
OS Type: linux
State: shut off
CPU(s): 1
Max memory: 262144 kB
Used memory: 262144 kB
the UUID is different. So it looks like the "define_domain_xml"
returns wrong UUID second time.
I am continuing to debug this, any hints are appreciated.
Sincerely,
Vadim
--
"La perfection est atteinte non quand il ne reste rien a ajouter, mais
quand il ne reste rien a enlever." (Antoine de Saint-Exupery)
5:53 p.m.
On Mar 31, 2008, at 11:40, Vadim Zaliva wrote:
I am trying to track down the problem.
OK, I have been able to reproduce the problem, is C, without Ruby.
Attached is source code
and XML file. Here is a sample output:
Attempt 0:
define
Domain defined with UUID 714b96db-a6b4-a4ea-ad58-39e4b44575c0
lookup by UUID 714b96db-a6b4-a4ea-ad58-39e4b44575c0
Lookup found domain with UUID 714b96db-a6b4-a4ea-ad58-39e4b44575c0
undefine
Attempt 1:
define
Domain defined with UUID 714b96db-a6b4-a4ea-ad58-39e4b44575c0
lookup by UUID 714b96db-a6b4-a4ea-ad58-39e4b44575c0
libvir: Xen Daemon error : GET operation failed:
Failed to lookup by UUID string domain
As you can see, it works OK first time, but the second time, returns
the same UUID, lookup on which fails.
The reason it fails is that the actual UUID is different second time:
virsh # dominfo sample-domain-lord
Id: -
Name: sample-domain-lord
UUID: b6eba85c-0f21-f79e-0607-1211d3fb4e36
OS Type: linux
State: shut off
CPU(s): 1
Max memory: 262144 kB
Used memory: 262144 kB
I am not sure if I can fix that myself.
Sincerely,
Vadim
--
"La perfection est atteinte non quand il ne reste rien a ajouter, mais
quand il ne reste rien a enlever." (Antoine de Saint-Exupery)
6:28 p.m.
On Mon, Mar 31, 2008 at 03:53:09PM -0700, Vadim Zaliva wrote:
On Mar 31, 2008, at 11:40, Vadim Zaliva wrote:
>I am trying to track down the problem.
OK, I have been able to reproduce the problem, is C, without Ruby.
Attached is source code
and XML file. Here is a sample output:
Attempt 0:
define
Domain defined with UUID 714b96db-a6b4-a4ea-ad58-39e4b44575c0
lookup by UUID 714b96db-a6b4-a4ea-ad58-39e4b44575c0
Lookup found domain with UUID 714b96db-a6b4-a4ea-ad58-39e4b44575c0
undefine
Attempt 1:
define
Domain defined with UUID 714b96db-a6b4-a4ea-ad58-39e4b44575c0
lookup by UUID 714b96db-a6b4-a4ea-ad58-39e4b44575c0
libvir: Xen Daemon error : GET operation failed:
Failed to lookup by UUID string domain
As you can see, it works OK first time, but the second time, returns
the same UUID, lookup on which fails.
The problem is that you are not freeing the virDomainPtr object
after you undefine the first VM. Libvirt caches virDomainPtr objects
based on the 'name' value. So the second time around you are getting
the cached handle. You are also leaking memory.
You need to call
virDomainFree(virDomainPtr dom)
to actually release the handle.
Dan.
--
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6:33 p.m.
On Mar 31, 2008, at 16:28, Daniel P. Berrange wrote:
The problem is that you are not freeing the virDomainPtr object
after you undefine the first VM. Libvirt caches virDomainPtr objects
based on the 'name' value. So the second time around you are getting
the cached handle. You are also leaking memory.
You need to call
virDomainFree(virDomainPtr dom)
to actually release the handle.
Thanks for the explanation. I will try this in my code.
However, I think this behavior is counter-intuitive. I was expecting
that undefining
domain should remove it from cache, or creating new domain with same
name should replace
old definition with a new one.
Sincerely,
Vadim
--
"La perfection est atteinte non quand il ne reste rien a ajouter, mais
quand il ne reste rien a enlever." (Antoine de Saint-Exupery)
8:17 p.m.
On Mar 31, 2008, at 16:28, Daniel P. Berrange wrote:
The problem is that you are not freeing the virDomainPtr object
after you undefine the first VM. Libvirt caches virDomainPtr objects
based on the 'name' value. So the second time around you are getting
the cached handle. You are also leaking memory.
You need to call
virDomainFree(virDomainPtr dom)
to actually release the handle.
I could not figure out how this could be expressed via Ruby bindings.
This function is called when object is freed, but when it happens is
controlled by GC.
For example, KDE Ruby binding are using dispose() method paradigm to
solve this kind of problem:
http://developer.kde.org/language-bindings/ruby/
Should we add one to Domain class?
Sincerely,
Vadim
P.S. I think the Python bindings have the same problem, virDomainPtr()
is called from __del__() there.
--
"La perfection est atteinte non quand il ne reste rien a ajouter, mais
quand il ne reste rien a enlever." (Antoine de Saint-Exupery)
11:24 a.m.
On Mon, Mar 31, 2008 at 06:17:44PM -0700, Vadim Zaliva wrote:
On Mar 31, 2008, at 16:28, Daniel P. Berrange wrote:
> You need to call
> virDomainFree(virDomainPtr dom)
> to actually release the handle.
I could not figure out how this could be expressed via Ruby bindings. This
function is called when object is freed, but when it happens is controlled
by GC.
For example, KDE Ruby binding are using dispose() method paradigm to solve
this kind of problem:
http://developer.kde.org/language-bindings/ruby/
Should we add one to Domain class?
[...]
P.S. I think the Python bindings have the same problem,
virDomainPtr() is
called from __del__() there.
OCaml bindings have the same problem as well, but it's not something I
feel any urge to fix there. To me it seems more like a C/libvirt bug.
Rich.
--
Richard Jones, Emerging Technologies, Red Hat http://et.redhat.com/~rjones
virt-p2v converts physical machines to virtual machines. Boot with a
live CD or over the network (PXE) and turn machines into Xen guests.
http://et.redhat.com/~rjones/virt-p2v
12:01 p.m.
On Wed, 2008-04-02 at 17:24 +0100, Richard W.M. Jones wrote:
OCaml bindings have the same problem as well, but it's not
something I
feel any urge to fix there. To me it seems more like a C/libvirt bug.
The Ruby bindings now have methods to call virXXXFree manually; but I
agree, it feels to me like leaking an implementation detail through the
API.
David
4:15 p.m.
On Wed, Apr 02, 2008 at 10:01:19AM -0700, David Lutterkort wrote:
On Wed, 2008-04-02 at 17:24 +0100, Richard W.M. Jones wrote:
> OCaml bindings have the same problem as well, but it's not something I
> feel any urge to fix there. To me it seems more like a C/libvirt bug.
The Ruby bindings now have methods to call virXXXFree manually; but I
agree, it feels to me like leaking an implementation detail through the
API.
Yes, the OCaml bindings too.
Rich.
--
Richard Jones, Emerging Technologies, Red Hat http://et.redhat.com/~rjones
virt-p2v converts physical machines to virtual machines. Boot with a
live CD or over the network (PXE) and turn machines into Xen guests.
http://et.redhat.com/~rjones/virt-p2v
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11 comments
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participants (4)
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Daniel P. Berrange -
David Lutterkort -
Richard W.M. Jones -
Vadim Zaliva