RFR: 8280056: gtest/LargePageGtests.java#use-large-pages failed "os.release_one_mapping_multi_commits_vm" [v4]

[Gerard Ziemski]

On Wed, 25 Oct 2023 13:38:04 GMT, Afshin Zafari <azafari at openjdk.org> wrote:

>> The `attempt_allocate_memory_at(addr, size)` may fail for some reasons that `::mmap`  will report. To find out why an attempt failed, an `int *` is passed down deep to the `::mmap` to return the `ERRNO` back to the callers.
>> This error code is used in gTest test case to show a proper message.
>> 
>> The changed test case never failed after 10K+ repetitions, but in case it happens in future the reason is also printed out.
>
> Afshin Zafari has updated the pull request incrementally with one additional commit since the last revision:
> 
>   remove extra parameter for windows and bsd versions.

So all of this effort at making the test more difficult is to try to make it fail more easily, correct?

test/hotspot/gtest/runtime/test_os.cpp line 565:

> 563:   ASSERT_NE(p, (address)nullptr);
> 564: 
> 565:   // reserve at border of the region

Can we have a bit more elaborate comment here, perhaps something like:

`// make things even more difficult by trying to reserve at the border of the region`

test/hotspot/gtest/runtime/test_os.cpp line 570:

> 568:   PRINT_MAPPINGS("B");
> 569: 
> 570:   ASSERT_TRUE(p2 == nullptr || p2 == border);

Why are we allowing this case to fail?

-------------

Changes requested by gziemski (Committer).

PR Review: https://git.openjdk.org/jdk/pull/16240#pullrequestreview-1732540720
PR Review Comment: https://git.openjdk.org/jdk/pull/16240#discussion_r1394520433
PR Review Comment: https://git.openjdk.org/jdk/pull/16240#discussion_r1394520375