IgnoreUnrecognizedVMOptions and badly specified options (original) (raw)

Dmitry Dmitriev dmitry.dmitriev at oracle.com
Thu Jun 25 12:17:30 UTC 2015

Hello,

Working with JVM command line options I noticed that "IgnoreUnrecognizedVMOptions" option allow to hide options with bad values. "IgnoreUnrecognizedVMOptions" allow to ignore unrecognized options, but it also allow to ignore improperly specified VM Options which are processed in general way, i.e. "-XX:" options processed by Arguments::process_argument function(hotspot/src/share/vm/runtime/arguments.cpp module).

I will be very appreciated if someone can describe this behavior or state that this is intentional.

Example for numeric and boolean options:

  1. Bad numeric option with and without "-XX:+IgnoreUnrecongnizedVMOptions" java -XX:MaxRAMFraction=-1 -version Improperly specified VM option 'MaxRAMFraction=-1' Error: Could not create the Java Virtual Machine. Error: A fatal exception has occurred. Program will exit.

java -XX:MaxRAMFraction=-1 -XX:+IgnoreUnrecognizedVMOptions -version java version "1.8.0_40" Java(TM) SE Runtime Environment (build 1.8.0_40-b26) Java HotSpot(TM) 64-Bit Server VM (build 25.40-b25, mixed mode)

  1. Bad boolean option with and without "-XX:+IgnoreUnrecongnizedVMOptions" java -XX:UseG1GC -version Missing +/- setting for VM option 'UseG1GC' Error: Could not create the Java Virtual Machine. Error: A fatal exception has occurred. Program will exit.

java -XX:UseG1GC -XX:+IgnoreUnrecognizedVMOptions -version java version "1.8.0_40" Java(TM) SE Runtime Environment (build 1.8.0_40-b26) Java HotSpot(TM) 64-Bit Server VM (build 25.40-b25, mixed mode)

So, as we see when "-XX:+IgnoreUnrecongnizedVMOptions" is used, bad "-XX:MaxRAMFraction=-1" and "-XX:UseG1GC" are ignored. I don't know is this behavior intentional or not, but HotSpot works in that way.

So, can someone tell me this is intentional? Or this behavior is wrong?

Thank you, Dmitry

More information about the hotspot-dev mailing list