R Model API will not start, gives PSOCK nodes error

Version/Environment (if relevant):

Domino version 4.6.2, possibly other 4.6 versions

Issue:

When publishing model API's written in R, you may see the following error: 

Error in stopOnLine(lineNum, file[lineNum], e) : ec2.internal model-2348234-234s34 model-2

Error on line #1: '.Domino.dir <- getSrcDirectory(function() {})' - 
Error in stopf("Cannot create %d parallel PSOCK nodes. Each node needs one connection but 
there are only %d connections left out of the maximum %d available on this R installation", : 
Cannot create 128 parallel PSOCK nodes. Each node needs one connection but there are only 
124 connections left out of the maximum 128 available on this R installation ec2.internal 
model-2348234-234s34

-0800 Calls: plumb ... tryCatchList -> tryCatchOne -> <Anonymous> -> 
stopOnLine c2.internal model-2348234-234s34

-0800 Execution halted

Root Cause:

Plumber's R code uses a package called parallely. When parallely determines number of available cores it not respect cgroup settings used for container CPU limits. Therefore, even if only given a fraction of total capacity, an R model deployed on a >= 128 core system will attempt to create 128 workers and fail when there are none available.

Resolution:

Please try adding this snippet to your environment's Dockerfile: 

Notes/Information:

Domino's recent environment images will include this snippet by default: 

ENV R_PARALLELLY_AVAILABLECORES_SYSTEM=4

The final fix is scheduled to be included in Domino version 5.2