[Openstack] [Tooz] Help in understanding DLM

Gary Kotton gkotton at vmware.com
Sat Aug 13 06:12:10 UTC 2016


It has been a process that has been evolving. We originally started with the mysql, then dropped this as it did not satisfy cases when a different DB was used. We then used memcached which was a disaster. The CPU of process/threads that would take a lock would spike and this killed the system performance. We then did a successful POC with redis and zookeeper. The result of that had us leaning towards zookeeper. All of this was done prior to the addition of the etcd driver.
In short we are leaning towards zookeeper as that has show the best results with stability and performance.
Thanks
Gary 

On 8/12/16, 10:54 PM, "Joshua Harlow" <harlowja at fastmail.com> wrote:

    Out of curiosity which backend is the vmware_nsx code defaulting to (or 
    recommending?)?
    
    -Josh
    
    Gary Kotton wrote:
    > Hi,
    >
    > In the vmware_nsx code base we make use of tooz extensively and the
    > results have been very good. Just depends on what type of backend you use J
    >
    > We wrote a wrapper that enables the deployer to decide on what type of
    > locking to use. This can be seen at:
    > https://urldefense.proofpoint.com/v2/url?u=https-3A__github.com_openstack_vmware-2Dnsx_blob_master_vmware-5Fnsx_common_locking.py-23L27&d=CwICaQ&c=Sqcl0Ez6M0X8aeM67LKIiDJAXVeAw-YihVMNtXt-uEs&r=VlZxHpZBmzzkWT5jqz9JYBk8YTeq9N3-diTlNj4GyNc&m=HO0A1e7KtYCcSKrtIEGRkHPTzii2qTHuoc2JzC7X8Tw&s=1zW-il5fRgf7bC2JK0MlU85n2v5MDb2LnVnk68A1r9Q&e= 
    >
    > Each project can decide on where to use DLM. It depends on each community.
    >
    > Thanks
    >
    > Gary
    >
    > *From: *ESWAR RAO <eswar7028 at gmail.com>
    > *Date: *Friday, August 12, 2016 at 12:44 PM
    > *To: *"openstack at lists.openstack.org" <openstack at lists.openstack.org>
    > *Subject: *[Openstack] [Tooz] Help in understanding DLM
    >
    > Hi All,
    >
    > Please let me know if any examples are there with Tooz library for
    > distributed locking.
    >
    > Just wanted to know even though we have database locks to prevent
    > concurrent updates and if applications are written well enough to handle
    > STALE updates, does DLM is needed for openstack services like Heat or
    > nova ??
    >
    > Thanks
    >
    > Eswar Rao
    >
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