[8u] RFR: 8280963: Incorrect PrintFlags formatting on Windows

[Severin Gehwolf]

Hi Alex,

On Mon, 2022-01-31 at 17:09 +0000, Alex Kashchenko wrote:
> Hi,
> 
> Please review a fix to 8u-only Windows-specific problem with
> -XX:+PrintFlags* output:
> 
> Bug: https://bugs.openjdk.java.net/browse/JDK-8280963
> 
> Webrev: https://cr.openjdk.java.net/~akasko/jdk8u/8280963/webrev.01/

+1 on using a partial backport for this usability issue as it reduces
risks as compared to a full JDK-8042893 backport.

Looks good to me.

Thanks,
Severin

> Problem description on Stack Overflow by Andrei Pangin:
> https://stackoverflow.com/a/63309395
> 
> The problem was fixed in jdk9 as part of JDK-8042893 [1], but this
> jdk9 change [2] doesn't look like a good candidate for the 8u backport
> according to 8u Best Practices [3]. Still the problem manifests itself
> as a customer-visible bug on Windows because people do use
> -XX:+PrintFlagsFinal to find out the actual flags picked up by JVM and
> can be confused by unexpected zeros in the output. Proposed patch
> cherry-picks the minimal change from JDK-8042893 commit [4].
> 
> Testing:
> 
>  - regression test is included with the proposed patch
>  - checked that it builds on Windows 64-bit and 32-bit on VS2017 and VS2010
>  - ran jtreg:hotspot/test/runtime on Windows and Linux
> 
> 
> [1] https://bugs.openjdk.java.net/browse/JDK-8042893
> [2] https://hg.openjdk.java.net/jdk9/jdk9/hotspot/rev/115188e14c15
> [3] https://mail.openjdk.java.net/pipermail/jdk8u-dev/2020-June/012002.html
> [4] https://hg.openjdk.java.net/jdk9/jdk9/hotspot/rev/115188e14c15#l53.1
> 
>