Clustering: odl-inventory not able to show 250 mininet switches (SR2)

I am unable to see 250 switches in inventory ds.

used build
https://nexus.opendaylight.org/content/repositories/staging/org/opendaylight/integration/distribution-karaf/0.2.2-Helium-SR2/distribution-karaf-0.2.2-Helium-SR2.tar.gz

steps to reproduce:
1) karaf start (i did with default values, which means 2G for java, 512m perm)
2) feature:install odl-restconf odl-mdsal-clustering
3) feature:install odl-openflowplugin-all
4) when cpu usage lowers down, start mininet with 250 modes
sudo mn --topo linear,250,1 --controller 'remote,ip=10.25.2.9,port=6653' --switch ovsk,protocols=OpenFlow13

5) then requests for /restconf/operational/opendaylight-inventory:nodes/
hrr

In [28]: url
Out[28]: 'http://10.195.91.134:8181/restconf/operational/opendaylight-inventory:nodes/'

In [29]: hdr
Out[29]:

In [30]: rsp = requests.get(url, headers=hdr, stream=False, auth=('admin', 'admin'))

In [31]: len(json.loads(rsp.content)['nodes']['node'])
Out[31]: 202

I got once even http status 500.