Summary

Define UseAltSigs and Xusealtsigs as obsolete.

Problem

History:

The JVM claimed SIGUSR1 and SIGUSR2 for the INTERRUPT and ASYNC signals, respectively.

-Xusealtsigs, mapping to -XX:+UseAltSigs, was provided to allow users to reclaim those signals and instead use two of the real-time signals (between SIGRTMIN and SIGRTMAX)

As of Solaris 10, Solaris provides SIGJVM1 and SIGJVM2 exclusively for the JVMs use. This avoids any conflict with user-defined signal usage.

As of Java 6 we documented that on Solaris 10 -Xusealtsigs/-XX:+UseAltSigs had no affect:

http://www.oracle.com/technetwork/java/javase/signals-139944.html#gbzbh

As we no longer support Solaris versions older than 10, we do not need the UseAltSigs functionality and the flags can be made Obsolete.

Solution

Move -XX:+/-UseAltSigs to the set of flags obsoleted in 9. Use of the flag now produces:

Java HotSpot(TM) 64-Bit Server VM warning: Ignoring option UseAltSigs; support was removed in 9.0

Explicitly issue a similar warning for -Xusealtsigs:

Java HotSpot(TM) 64-Bit Server VM warning: Ignoring option -Xusealtsigs; support was removed in 9.0

Remove mention of these flags from the man pages.

Add a release note describing the change if deemed necessary.

Specification

Use of the -XX:+UseAltSigs flag now produces:

Java HotSpot(TM) 64-Bit Server VM warning: Ignoring option UseAltSigs; support was removed in 9.0

Use of the -Xusealtsigs flag now produces:

Java HotSpot(TM) 64-Bit Server VM warning: Ignoring option -Xusealtsigs; support was removed in 9.0