Monday, October 21, 2019

ONTAP 9.6+: REST API: netapp_ontap: performance of get_collection() vs. get()

NetApp's ONTAP 9.6 introduced new REST API along with a new python module netapp_ontap.


import time
import getpass
import netapp_ontap

from netapp_ontap import config
from netapp_ontap.host_connection import HostConnection
from netapp_ontap.resources import QuotaRule

password = getpass.getpass()

config.CONNECTION = HostConnection(host, user, password)

start = time.time()
quota_rules = QuotaRule.get_collection(fields='type')
# quota_rules = QuotaRule.get_collection()
total = 0
for l in quota_rules:
    # l.get(fields='type')
    total = total + 1
end = time.time()

With 471 quota rules on my filer it takes about 4s with get_collection(fields='type') vs. ~40s when calling l.get(fields='type') for each rule being processed. So if you are after all the entries it is more quicker to pass the required fields to get_collection() and not call get() on each returned resource.

I did a little bit of debugging and it seems that each get() results in a new TCP/HTTPS connection being established which is likely the main reason of the much worse performance performance. Also get_collection() gets all 471 results in a single HTTP GET.

There seems to be a bug in regards to re-ussing connections though, as it shouldn't have to establish a new session for each get.