Strange Failure

We currently use ES 0.19.0 release. We have a cluster with two nodes. Nodes
are located on two different virtual machines which are on the same
physical server. Yesterday, we had an DS outage. There were no OutOfMemory
exceptions. Both nodes continue to work individually. When I checked logs
of both DS servers, I found following exceptions:

Also, I found a bug in one of our processes. This bug causes index
creation/deletion every minute and this situation continued for 4 hours
before DS restart. This means that 240 index creation/deletion operation
performed before this problem occurred. May this cause the node failure?

any ideas about this problem?

Mustafa Sener