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Going from memory of the code I believe this is possible. Iirc the lock is
a select for update so assuming innodb it will prevent two workers from
assigning the same network to multiple tenants but won't prevent two
networks being assigned to the same tenant. This is probably an untested
consequence of clan plus multi host. A decent workaround would be to assign
a network to a tenant immediately after creation instead of lazily.
On Feb 5, 2013 12:56 PM, "rezroo" <reza at dslextreme.com> wrote:

>  I've run into this issue and I'd like to get some opinions before logging
> a defect. I'm using folsom, deployed using VlanManager.  It seems to me
> that the assignment of a network to a tenant is lazy evaluated until the
> first instance for the project is launched.  This can be confirmed by
> creating a new tenant and then doing 'nova-manage network list'. If one now
> launches multiple tenants by setting the number of instances to 4 or 5 then
> there is a race condition and it is possible that two or more vlan/networks
> are assigned to the tenant. I'm running into this issue.
>
> I posted to Openstack-operators already and I got one reply back claiming
> that this is a configuration issue, without any insight as to what is
> misconfigured. Do you know what kind of misconfiguration leads to this? Or
> what concurrency/locking mechanism prevents this from happening?
> Presumably a select is done in the networks table to see if a vlan is
> already assigned to a tenant.  If you have sufficiently fast environment it
> is possible that two simultaneous queries are done, both with no results,
> and two networks are assigned and committed to the database.  This is what
> happened for me.  What misconfiguration should I look for, or what
> concurrency/locking mechanism is there to prevent this?
>
> Or I can log a defect.
>
> Thanks,
> Rez
>
> -------- Original Message --------  Subject: Re: [Openstack-operators]
> Simultaneous launch of multiple instances from horizon leads to multiple
> LANs assigned to new tenant  Date: Tue, 05 Feb 2013 05:41:37 -0800  From: rezroo
> <reza at dslextreme.com> <reza at dslextreme.com>  To: Vivek Singh Raghuwanshi
> <vivekraghuwanshi at gmail.com> <vivekraghuwanshi at gmail.com>
>
> Still using nova-network due to its better integration with Horizon.
> Do you know what kind of misconfiguration leads to this? Or what
> concurrency/locking mechanism prevents this from happening?  So presumably
> a select is done in the networks table to see if a vlan is already assigned
> to a tenant.  If you have sufficiently fast environment it is possible that
> two simultaneous queries are done, both with no results, and two networks
> are assigned and committed to the database.  This is what happened for me.
> What misconfiguration should I look for, or what concurrency/locking
> mechanism is there to prevent this?
> Thanks,
> Rez
>
> On 02/04/2013 11:03 PM, Vivek Singh Raghuwanshi wrote:
>
> This only happens due to misconfiguration, but are you still with
> nova-network.
> its advisable to switch your  cloud with Quantum
>
> On Tue, Feb 5, 2013 at 5:05 AM, rezroo <reza at dslextreme.com> wrote:
>
>> Hi - I'm wondering if others have seen this defect and if it has already
>> been reported or not.
>> I'm using folsom, deployed using VlanManager.
>> When a new tenant is created no vlan/network is assigned to it until the
>> first instance for the project is launched.  This can be confirmed by
>> creating a new tenant and then doing 'nova-manage network list'.
>> If now one launches multiple tenants by setting the number of instances
>> to 4 or 5 then there is a race condition and it is possible that two or
>> more vlan/networks are assigned to the tenant.
>> Should I log this as a defect?
>> Thanks,
>> Rez
>>
>> _______________________________________________
>> OpenStack-operators mailing list
>> OpenStack-operators at lists.openstack.org
>> http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-operators
>>
>
>
>
> --
> ViVek Raghuwanshi
> Mobile -+91-09595950504
> Skype - vivek_raghuwanshi
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>
>
>
>
>
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