RFR: 8255072: [TESTBUG] com/sun/jdi/EATests.java should not fail if expected VMOutOfMemoryException is not thrown

[Richard Reingruber]

On Thu, 22 Oct 2020 14:29:28 GMT, Chris Plummer <cjplummer at openjdk.org> wrote:

>> You mentioned the possibility that the OOME is not thrown because it is another thread that consumes all memory than the one calling forceEarlyReturn() which is supposed to fail with OOME. TLAB could be an issue then. In general GC could have a heuristic in place to raise OOME in greedy threads when another thread would still be able to allocate successfully. I think I could change the debugger part to call consumeAllMemory() in the debuggee. This should be executed in the same jdwp agent thread as the later forceEarlyReturn.
>> 
>> But honestly I don't think it is worth it and I cannot even test if it fixes the issues. I'd prefer to skip the 3 test cases if running with ZGC. Please let me know what you prefer.
>
>> But honestly I don't think it is worth it and I cannot even test if it fixes the issues. I'd prefer to skip the 3 test cases if running with ZGC. Please let me know what you prefer.
> 
> That's one option if this only happens with ZGC. You also mentioned doing retries. I would only suggest that if you think you can limit the chances of the OOME not happening to be so unlikely that we are no likely to ever see it happen.

With the last commit the combined change is

- The 3 problematic test cases are skipped if ZGC is selected.

- They are also skipped if no OOME during object reallocation can be expected
  because allocations are not eliminated.

- In consumeAllMemory, as a last step, empty LinkedList nodes are created
  without long array to fill up small blocks of free memory.

- EATests.java is removed from the problem list for ZGC.

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PR: https://git.openjdk.java.net/jdk/pull/775