Puma traps SIGUSR2 and treats it as a signal to restart itself. However, Java Flight Recorder uses that same signal for its internal functioning. Java Flight Recorder is a very useful, commonly used diagnostic tool in the Java world, and is used by JRuby and TruffleRuby maintainers and end users. Unfortunately we can't use it on Puma processes without making a fork of Puma that disables SIGUSR2 trapping.

Would you guys accept a pull request where I skipped the setup of SIGUSR2 handling in setup_signals if the environment variable SKIP_SIGUSR2_HANDLING was present?