RFR: 8213269: convert test/hotspot/jtreg/runtime/memory/RunUnitTestsConcurrently to gtest [v6]

[Coleen Phillimore]

On Tue, 2 Mar 2021 00:55:16 GMT, Mikhailo Seledtsov <mseledtsov at openjdk.org> wrote:

>> This is a preliminary review. I would like to get the initial feedback before I proceed with conversion of the remaining tests.
>> 
>> Here is what I did so far:
>>   - created a UnitTestThread and a main test runner, based on gtests with similar needs
>>   - moved the original code from HotSpot internals (so called hotspot internal tests: src/hotspot/share/memory/virtualspace.cpp)
>>     to the newly created gtest while wrapping it into a TestReservedSpace class. I did not change the code of the test.
>>   - removed invocations from whitebox.cpp
>> 
>> Testing:
>>   - ran GTestWrapper on usual platforms - All PASS
>>   - ensured that ReservedSpaceConcurrent is in the logs and passed
>> 
>> After gathering the feedback my plan is:
>> Plan:
>>   - move the remaining internal Memory/VirtualSpace tests into a gTest
>>     - I am thinking about using separate files for each test
>>   - create a common file for UnitTestThread and MultiThreadTestRunner to reuse the code
>
> Mikhailo Seledtsov has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Using regular brackets in initializer list instead of curly brackets

test/hotspot/gtest/concurrent_test_runner.inline.hpp line 74:

> 72:     Semaphore done(0);
> 73: 
> 74:     std::vector<UnitTestThread*> t;

Regarding the STL question, I think using std in a limited fashion in the tests seems ok before we start allowing it in the main sources, despite where Misha pointed out it already exists.  It's going to be allowed pretty soon anyway.
One question about this: where does it allocate memory for 't' ?  Are the elements leaked here?

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PR: https://git.openjdk.java.net/jdk/pull/2436