When jspawnhelper fails for whatever reason, but more prominently due to JDK-8325621, it will report the errors into stdout, but not to the relevant IOException. So, if the application is configured to only capture the exception logs (e.g. through java.util.logging), we will miss any output from jspawnhelper, it user would be left without a clue what have happened. We have seen customers spending weeks trying to figure out what went wrong.

It would be good to provide useful IOException when jspawnhelper fails. We already have a precedent with vmError printing helpful suggestions when VM fails, we can do the same here. Something like: https://github.com/openjdk/jdk/compare/master...shipilev:JDK-8352533-jspawnhelper-ioexceptions