Controller went out of memory after connecting 40 openflow switches in fully mesh topology

1) Run karaf
2) Enable the below features
feature:install odl-openflowplugin-flow-services
feature:install odl-dlux-all
feature:install odl-l2switch-all
feature:install odl-l2switch-switch-ui
feature:install odl-l2switch-switch-rest

3) Using mininet connect 40 switches in fully mesh topology
4) Controller console is unresponsive for few minutes.
5) Then it throws the below exception.
Exception in thread "odl-stat-rpc-oper-thread-0" java.lang.OutOfMemoryError: Java heap space
at java.util.Arrays.copyOf(Arrays.java:2367)
at java.lang.AbstractStringBuilder.expandCapacity(AbstractStringBuilder.java:130)
at java.lang.AbstractStringBuilder.ensureCapacityInternal(AbstractStringBuilder.java:114)
at java.lang.AbstractStringBuilder.append(AbstractStringBuilder.java:415)
at java.lang.StringBuilder.append(StringBuilder.java:132)
at java.lang.Throwable.toString(Throwable.java:481)
at org.apache.log4j.OsgiThrowableRenderer.doRender(OsgiThrowableRenderer.java:97)
at org.apache.log4j.OsgiThrowableRenderer.doRender(OsgiThrowableRenderer.java:118)

6) I see all 40 openflow sessions.
netstat -ant | grep 6633 | grep ESTABLISHED | wc -l
40

7) But rest call shows me only 20 nodes.
http://10.11.200.254:8181/restconf/operational/opendaylight-inventory:nodes