[ovirt-users] Delay difference between queries (Python vs REST)

[Juan Hernández]

On 01/17/2017 04:59 PM, Nicolas Ecarnot wrote:
> Le 17/01/2017 à 16:26, Juan Hernández a écrit :
>> On 01/17/2017 03:56 PM, Nicolas Ecarnot wrote:
>>> Hello,
>>>
>>> On a 3.6.5 DC, I'm trying to figure out how many VMs there are, using
>>> two methods :
>>>
>>> _*Python SDK :*_
>>>
>>> *from ovirtsdk.xml import params
>>> from ovirtsdk.api import API
>>> api = API(url='https://engine.fqdn/ovirt-engine/api',
>>> username='admin at internal', password='xxx', insecure=True)
>>> print len(api.vms.list())*
>>>
>>> time ./getMvm.py
>>> 62
>>>
>>> real    0m23.016s
>>> user    0m22.288s
>>> sys    0m0.054s
>>>
>>>
>>> _*REST :*_
>>>
>>> *time curl -H "Version: 3" -H "Prefer: persistent-auth" -H "Filter:
>>> false" -H "Accept: application/xml" -H "Content-Type: application/xml"
>>> -k -u 'admin at internal:xxx' https://***engine.fqdn*/ovirt-engine/api/vms*
>>>
>>> (Then grep or anything that would get the values from the xml returned.)
>>>
>>> real    0m0.383s
>>> user    0m0.036s
>>> sys    0m0.038s
>>>
>>>
>>> I am a beginner in both methods, but I would prefer play with Python.
>>> I'm very surprised to have to wait more than 20 seconds to get an
>>> answer.
>>> Looking at the engine log, I see that the authentication part is
>>> finished after say 3 seconds, then 20 seconds with absolutely no error
>>> message, no CPU load, no RAM burst, no nothing.
>>> On the SPM, exactly triple null nothing nada niet void is obviously
>>> explaining such a delay.
>>>
>>> I'm wondering if this super hyper sluggishness is somewhat related to
>>> the GUI global slowness I'm experiencing like other users since we left
>>> 3.2.x, and I would love that some oVirt ninja uses the comparison above
>>> to tell what parts in oVirt is used or not that could explain such a
>>> difference (database, access to SPM, LVM, network access, whatever...)
>>>
>>> -- 
>>> Nicolas ECARNOT
>>>
>>
>> The performance problem is inside version 3 of the Python SDK. That is
>> one of the reasons that we had to do a new version of the Python SDK for
>> version 4 of the engine. If you are using version 4 of the engine then
>> you can use version 4 of the SDK:
>>
>>   https://github.com/oVirt/ovirt-engine-sdk/tree/master/sdk
>>
>> https://github.com/oVirt/ovirt-engine-sdk/blob/master/sdk/examples/list_vms.py
>>
>>
>> It should be much faster. Would be nice if you can repeat your test and
>> report the results.
>>
> 
> Hello Juan,
> 
> Indeed, you were right. I tried the same from a recent server with a
> recent SDK, and I let you have a look :
> 
> # rpm -q python-ovirt-engine-sdk4
> python-ovirt-engine-sdk4-4.0.1-1.el7.centos.x86_64
> 
> # time ./getMvm.py
> 62
> 
> real    0m1.004s
> user    0m0.234s
> sys    0m0.031s
> 
> And repeating the same test gives a very decent average, so thank you.
> 

Twenty times faster, approx, good to know. Thanks. By the way, if you
want even better performance, then make sure to disable debug and enable
compression:

  connection = sdk.Connection(
    ...
    debug=False,
    compress=True,
  )