RFR: 8302508: Add timestamp to the output TraceCompilerThreads

[Vladimir Kozlov]

Having timestamps added to the output of TraceCompilerThreads will be helpful in understanding how frequently the compiler threads are being added or removed.

I did that and also added UL output.


java -XX:+TraceCompilerThreads -XX:+PrintCompilation -version

     86 Added initial compiler thread C2 CompilerThread0
     86 Added initial compiler thread C1 CompilerThread0
     92    1       3       java.lang.Object::<init> (1 bytes)
     96    2       3       java.lang.String::coder (15 bytes)

java -Xlog:jit+thread=debug -Xlog:jit+compilation=debug -version

[0.078s][debug][jit,thread] Added initial compiler thread C2 CompilerThread0
[0.078s][debug][jit,thread] Added initial compiler thread C1 CompilerThread0
[0.083s][debug][jit,compilation]    1       3       java.lang.Object::<init> (1 bytes)
[0.087s][debug][jit,compilation]    2       3       java.lang.String::coder (15 bytes)


Tested tier1.

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Commit messages:
 - 8302508: Add timestamp to the output TraceCompilerThreads

Changes: https://git.openjdk.org/jdk/pull/12898/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=12898&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8302508
  Stats: 44 lines in 1 file changed: 28 ins; 0 del; 16 mod
  Patch: https://git.openjdk.org/jdk/pull/12898.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/12898/head:pull/12898

PR: https://git.openjdk.org/jdk/pull/12898