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

[David Holmes]

On Thu, 24 Sep 2020 18:14:10 GMT, Zhengyu Gu <zgu at openjdk.org> wrote:

> For some non-JavaThread, their object instances can outlast threads' lifespan. For example, we still can query/report
> thread's state after thread terminated.
> But the query/report currently returns wrong state. E.g. a terminated thread appears to be alive and seemly has valid
> thread stack, etc.
> This patch sets non-JavaThread's state to ZOMBIE just before it terminates, so that we can distinguish terminated
> thread from live thread.
> Also, thread should not report its SMR info, if it has terminated or it never started (thread->osthread() == NULL).
> 
> Note: Java thread does not have such issue, its thread object is deleted before thread terminates.

src/hotspot/share/runtime/thread.cpp line 919:

> 917:     osthread()->print_on(st);
> 918:
> 919:     if (osthread()->get_state() != ZOMBIE) {

I'm not sure print_on(), as opposed to print_on_error() can ever be called with a ZOMBIE thread. I didn't expect any
change in this method.

src/hotspot/share/runtime/thread.cpp line 955:

> 953:     }
> 954:   } else {
> 955:     st->print(" Aborted");

Not sure this is reachable and if it is then I'm not sure what state the thread is actually in. If a Thread never gets
an osThread() it isn't started so shouldn't be locatable by any means.

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