RFR: 8253429: Error reporting should report correct state of terminated/aborted threads

[Thomas Stuefe]

On Mon, 28 Sep 2020 04:47:47 GMT, David Holmes <dholmes at openjdk.org> wrote:

>> For thread, e.g. G1ConcurrentMarkThread, there is nothing to prevent calling _cm_thread->print_on(tty) after it
>> terminated, although, I can not find a case right now.
>> You prefer an assertion instead?
>
> I prefer no change to this method. I don't see that we need to do anything special even if a ZOMBIE could be
> encountered.

If Thread::print_on() (and ThreadsSMRSupport::print_info_on(Thread..)) cannot be called for a Zombie thread, I'd prefer
an assertion testing that.

>> so, you prefer "ShouldNotReachHere()" ?
>
> There's no point putting a ShouldNotReachHere() in error handling code as we will just trip a secondary error.
> If we want to print something the perhaps "unknown state (no osThread)" ?
> Also I only wanted the ThreadSMRSupport::print_info_on to be excluded for Zombies, but you've excluded it for the
> no-osThread case as well. I think based on what Dan said we can just put that back and call it unconditionally. Thanks.

+1 for "unknown state". "Aborted" is misleading since we do not know. Could have crashed right at thread creation (or
is that what "Aborted" means?)

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PR: https://git.openjdk.java.net/jdk/pull/341