I am trying to use the parallel execution nodes to process an R Snippet node. In my workflow I have a Parallel Chunk Start node (configured for 4 chunks), an R Snippet Node, then a Parallel Chunk Stop node. If I execute the Parallel Chunk Stop node I see a Parallel Chunk Start and 3 Virtual Starts in the Knime console. top on my linux machine shows 4 R processes running, then I see the 4 chunks end. After this is done, the Parallel Chunk End bnode reports an error:
Execute failed: Runtime class of object "0.07" (index 2) in row "1_#2" is DoubleCell and does not comply with its supposed superclass StringCell
After this failure, the R Snippet node has a data output that appers to be complete as expectyed with one string column and 5 double columns. I tried passing this table through a Column rename node before the Parallel Chunk Stop node. The columns get renamed properly, but the Parallel Chunk Stop node fails again. I also tried to convert all columns to strings, but many of the cells in my table were left with missing values.
Suggestion on how to complete this parallel execution workflow would be appreciated.