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

[Ioi Lam]

On Fri, 16 Jul 2021 04:19:28 GMT, Xin Liu <xliu at openjdk.org> wrote:

>> 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
>
> I think it better off use LogMessage to guarantee multiple-lines are not separated. 
> then I realize that this is very beginning,  other threads haven't been up yet. so it's fine.

Thanks @navyxliu @tstuefe @dholmes-ora @yminqi for the review.

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