RFR: 8319055: JCMD should not buffer the whole output of commands

[Alex Menkov]

On Tue, 4 Feb 2025 07:01:52 GMT, Thomas Stuefe <stuefe at openjdk.org> wrote:

> With streaming, what is the expected behavior if a command takes too long? Jcmd stops with timeout, and the hotspot JVM then discards the results?

When a tool is run interactively (I mean not as part of a testing) there is no timeouts - the tools forward any output from the target VM to stdout until communication channel (socket/pipe) is closed.
With streaming the tool just prints command output earlier.
If jcmd is killed while the command is in progress, the VM completes the command anyway (we don't have a way to stop it), results are discarded.

> Unless the tests are easy to fix, I don't see any problem with just running them in old buffered mode.

Yes, this is the plan for the next step - fix the tests of disable streaming output.

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PR Comment: https://git.openjdk.org/jdk/pull/23405#issuecomment-2634946997