`jcmd` provides great diagnostics but many commands lack a timestamp in their output. Adding a timestamp to the output of some would add value for those debugging JVM data.
Some diagnostic commands already provide timestamps. For example `Thread.print` already prints timestamp in a "yyyy-MM-dd HH:mm:ss" format. Adding timestamps to all diagnostic `jcmd` commands with a non-throw-away STDOUT. The exceptions are: * `VM.uptime` - command run with `-date` argument will also print a timestamp; * `VM.system_properties` - already lists timestamp * `Thread.dump_to_file` - the content dumped to file already has a timestamp; * `VM.version` ------------- Commit messages: - copyright change - Thread.dump_to_file doesn't need timestamp in STDOUT - CodeCacheTest.java and ClassHierarchyTest.java to account for added timestamp - jcmd [PID] Compiler.perfmap has no valuable stdout. Remove timestamp from Compiler.perfmap - 8357828: add timestamps to jcmd diagnostic commands Changes: https://git.openjdk.org/jdk/pull/27368/files Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=27368&range=00 Issue: https://bugs.openjdk.org/browse/JDK-8357828 Stats: 45 lines in 4 files changed: 38 ins; 3 del; 4 mod Patch: https://git.openjdk.org/jdk/pull/27368.diff Fetch: git fetch https://git.openjdk.org/jdk.git pull/27368/head:pull/27368 PR: https://git.openjdk.org/jdk/pull/27368
