RFR: 8255908: ExceptionInInitializerError due to UncheckedIOException while initializing cgroupv1 subsystem [v3]

[Poonam Bajaj]

On Fri, 20 Nov 2020 09:27:56 GMT, Severin Gehwolf <sgehwolf at openjdk.org> wrote:

>> Poonam Bajaj has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   Added UnchedkedIOException catch blocks for sumTokensIOStat and getLongEntry methods
>
> This seems OK. Ideally, I'd like for this to be tested. If it's interrupts it's going to be difficult. Missing files should be easy enough to test.
> 
> Aside: We really need to streamline file reading. We have too many of them unnecessarily all over the place. [JDK-8254001](https://bugs.openjdk.java.net/browse/JDK-8254001) should fix that. I'll prioritize it.

@jerboaa Thanks for the review. As for the missing files, looks like mountInfoFileNotFound() and cgroupsFileNotFound() should be testing it. 

This issue is being faced by a customer and they encountered failures due to interrupts during reading. These changes have been verified by them.

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PR: https://git.openjdk.java.net/jdk/pull/1303