Updating the memory RAM from 2GB to 4GB has corrected the problem.
The number and speed of the CPU cores, the amount of RAM and the size, performance and nature of the file store infrastructure should be scaled according to size of the installation and expected workload.
Note that adding input and output clients, the type of files being processed and the number of jobs to be held are what drives the memory requirements up.
For installations we recommend the higher number.
Development System 8-16GB
QA System 16-32GB
Production System 32-64GB
UPDATED: July 28, 2017