On Fri, 19 Sep 2025 07:02:35 GMT, Alan Bateman <[email protected]> wrote:
>> `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`
>
> src/hotspot/share/services/diagnosticCommand.cpp line 1093:
>
>> 1091:
>> 1092: void ThreadDumpToFileDCmd::execute(DCmdSource source, TRAPS) {
>> 1093: print_local_time(output());
>
> I assume you didn't mean to print a time stamp here as the output already has
> a timestamp. Also for -format=json and sending the output to stdout, then it
> will be unparsable if a timestamp appears before the JSON object.
Hi Alan. That's right.
My mistake. I declared the intention to not have timestamps for commands with a
throwaway `stdout`. This also includes "Thread.dump_to_file" command but then
mistakenly added `print_local_time()` in here.
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PR Review Comment: https://git.openjdk.org/jdk/pull/27368#discussion_r2362306527
