Jobs I start with jstart often just stop working after a few days. Although there have been cases of memory problems, often the jobs stop without leaving anything useful in the logs (which might be related to https://phabricator.wikimedia.org/T85775). Here's how I start the jobs, simplified a bit:
jstart -N fr-feedcheck -mem 4500m java -Xmx180M -cp /path/to/wikipedia/languagetool-wikipedia.jar org.languagetool.dev.wikipedia.atom.AtomFeedCheckerCmd (+more options...)
I know that the jobs stop because they stop writing data to the DB and then the web app that uses this DB stops working. The same jobs used to be *much* more stable until around December 2014, I had jobs running for months without problems.