R Error: java.lang.OutOfMemoryError: Java heap space
You need to make sure you're allocating additional memory before loading rJava or any other packages. Wipe the environment first (via rm(list = ls())), restart R/Rstudio if you must, and modify the options at the beginning of your script.
options(java.parameters = "-Xmx8000m")
See for example https://support.snowflake.net/s/article/solution-using-r-the-following-error-is-returned-javalangoutofmemoryerror-gc-overhead-limit-exceeded
I somehow had this problem in a not reproducible manner, partly solved it with -Xmx8g but run in to problems randomly.
I now found an option with a different garbage collector by using
options(java.parameters = c("-XX:+UseConcMarkSweepGC", "-Xmx8192m"))library(xlsx)at the beginning of the script and before any other package is loaded since other packages can load some java things by themselves and the options have to be set before any Java is loaded.
So far, the problem didn't occurred again.
Only sometimes in a long session it can still happen. But in this case a session restart normally solves the problem.