dfuse complains about ulimit on startup

[matthewdarwin]

using a non-root user with no permissions:

on dfuse startup (mindreader-stdin)

 (dfuse) ulimit max open files before adjustment (cli/setup.go:93){"current_value": 64000}
 (dfuse) unable to use our good enough ulimit max open files value, going to try with something lower (cli/setup.go:110){"error": "cannot set ulimit max open files: operation not permitted"}
 (dfuse) ulimit max open files after adjustment (cli/setup.go:152){"current_value": 24576}

[matthewdarwin]

Not sure why there is an error "cannot set ulimit max open files: operation not permitted". What is dfuse trying to do?