[Rev 01] RFR: Add a limition to allocate object heap in aarch64 with tsan enabled.

[Jie He]

On Tue, 21 Apr 2020 19:08:31 GMT, Man Cao <manc at openjdk.org> wrote:

>> Jie He has refreshed the contents of this pull request, and previous commits have been removed. The incremental views
>> will show differences compared to the previous content of the PR. The pull request contains one new commit since the
>> last revision:
>>   Add a limit to allocate object heap in aarch64 with tsan enabled.
>>   
>>   Vm will calculate max heap size according to the physical ram if user
>>   doesn't specify the size(-Xmx). However, with tsan 48-bits memory
>>   mapping of aarch64, it's hard to allocate the large continuous vm
>>   space. Heap allocation often fail in this case, thus, add a limit
>>   at os::has_allocatable_memory_limit to prevent to exceed the
>>   avaiable size. Currently, only support 48-bits address space.
>>   
>>   Can reproduce the behavior by launching "java --version" in a machine
>>   with huge physical memory.
>>   
>>   Change-Id: Iabff934444091436bc657978e2e947c270398f29
>
> Changes requested by manc (Reviewer).

RFR, I updated the code, thank you.

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PR: https://git.openjdk.java.net/tsan/pull/6