RFR: 8273112: -Xloggc and -Xlog should override -verbose

[Xiaowei Lu]

According to java 16 specifications for java command (https://docs.oracle.com/en/java/javase/16/docs/specs/man/java.html), the command line option -Xloggc should override -verbose:gc if both options are given with the same java command. However, gc information still outputs to console even if gc log file is specified.

$java -Xloggc:gc.log -verbose:gc -version
[0.000s][warning][gc] -Xloggc is deprecated. Will use -Xlog:gc:gc.log instead.
[0.003s][info ][gc] Using G1
$cat gc.log
[0.003s][info][gc] Using G1

In addition, since -Xloggc:filename is replaced by -Xlog:gc:filename, can we assume that -Xlog:gc:filename should override -verbose:gc as -Xloggc:filename? Currently, gclog still outputs to both stdout and file if -Xlog and -verbose are given with the same java command.

$java -Xlog:gc:gc.log -verbose:gc -version
[0.003s][info][gc] Using G1
$cat gc.log
[0.003s][info][gc] Using G1

As a result, we propose to put off the log configuration of -verbose option until we are confident that there isn’t -Xloggc or -Xlog options.

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Commit messages:
 - 8273112: -Xloggc and -Xlog should override -verbose

Changes: https://git.openjdk.java.net/jdk/pull/5295/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=5295&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8273112
  Stats: 52 lines in 3 files changed: 46 ins; 2 del; 4 mod
  Patch: https://git.openjdk.java.net/jdk/pull/5295.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/5295/head:pull/5295

PR: https://git.openjdk.java.net/jdk/pull/5295