RFR: 8270801: Print VM arguments with java -Xlog:arguments

[Ioi Lam]

It's useful to print VM arguments to the log file, especially when you are logging several JVM invocations:


$ java -cp foo -Xlog:gc:file=a.log -Xcomp com.Foo
$ java -cp foo -Xlog:gc:file=b.log -Xint com.Foo


After a while, you may forget which process created a.log and which created b.log. Adding vm arguments into the log file will help distinguishing them:


$ java -cp foo -Xlog:gc,arguments:file=a.log -Xcomp com.Foo
$ java -cp foo -Xlog:gc,arguments:file=b.log -Xint com.Foo

$ grep jvm_args a.log b.log
a.log:[0.015s][info][arguments] jvm_args: -Xlog:gc,arguments:file=a.log -Xint
b.log:[0.001s][info][arguments] jvm_args: -Xlog:gc,arguments:file=b.log -Xcomp


Here's an example of what the log looks like:


$ java -Xlog:arguments -Xshare:on -cp ~/tmp -Dxx=yy -esa HelloWorld 1 2 3
[0.001s][info][arguments] VM Arguments:
[0.001s][info][arguments] jvm_args: -Xlog:arguments -Xshare:on -Dxx=yy -esa
[0.001s][info][arguments] java_command: HelloWorld 1 2 3
[0.001s][info][arguments] java_class_path (initial): /home/user/tmp
[0.001s][info][arguments] Launcher Type: SUN_STANDARD
Hello World

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Commit messages:
 - 8270801: Print VM arguments with java -Xlog:arguments

Changes: https://git.openjdk.java.net/jdk/pull/4801/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=4801&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8270801
  Stats: 5 lines in 1 file changed: 5 ins; 0 del; 0 mod
  Patch: https://git.openjdk.java.net/jdk/pull/4801.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/4801/head:pull/4801

PR: https://git.openjdk.java.net/jdk/pull/4801