When sending a large json string to DeployR to be processed, it appears that the processing runs fine on R itself. However, when retrieving the large results (example: stored in variable called json_out) via the DeployR java client library, you may see the following warning:
"warnings:[Retrieving R object exception: R session object (json_out) could not be fetched, ex=R session object (json_out) fetch request (1669352.0b) exceeds max supported retrieval size (524288.0b).]".
The 512K result size limit being hit is a throttle limit set for Rserve on each grid node. See where this property is set in the admin console in the attached screen shot. This is set to keep over-sized object data requests from swamping the server.
The limit can be increased to accommodate large results but the change is a not a global setting. It must be increased on each node in the grid.
