RFR(xs): 8225200: runtime/memory/RunUnitTestsConcurrently.java has a memory leak

[Stefan Karlsson]

On 2019-07-01 20:56, Thomas Stüfe wrote:
> Hi all,
>
> may I please have reviews and opinions about the following patch:
>
> Issue: https://bugs.openjdk.java.net/browse/JDK-8227041
> cr:
> http://cr.openjdk.java.net/~stuefe/webrevs/8227041-rununittestsconcurrently-has-a-mem-leak/webrev.00/webrev/index.html
>
> There is a memory leak in test_virtual_space_list_large_chunk(), called as
> part of the whitebox tests WB_RunMemoryUnitTests(). In this test metaspace
> allocation is tested by rapidly allocating and subsequently leaking a
> metachunk of ~512K. This is done by a number of threads in a tight loop for
> 15 seconds, which usually makes for 10-20GB rss. Test is usually OOM killed.
>
> This test seems to be often excluded, which makes sense, since this leak
> makes its memory usage difficult to predict.
>
> It is also earmarked by Oracle for gtest-ification, see 8213269.
>
> This leak is not easy to fix, among other things because it is not clear
> what it is it wants to test. Meanwhile, time moved on and we have quite
> nice gtests to test metaspace allocation (see e.g.
> test_metaspace_allocation.cpp) and I rather would run those gtests
> concurrently. Which could be a future RFE.
>
> So I just removed this metaspace related test from WB_RunMemoryUnitTests()
> altogether, since to me it does nothing useful. Once you remove the leaking
> allocation, not much is left.
>
> Without this part RunUnitTestsConcurrently test runs smoothly through its
> other parts, and in that form it is still useful.
>
> What do you think?

I think this makes sense and it looks good to me.

Thanks,
StefanK

>
> Cheers, Thomas