RFR: 8319242: HotSpot Style Guide should discourage non-local variables with non-trivial initialization or destruction

[Stefan Karlsson]

On Sun, 15 Jun 2025 05:15:11 GMT, Kim Barrett <kbarrett at openjdk.org> wrote:

> Please review this change to the HotSpot Style Guide to add discussion of how
> we prefer to handle initialization and destruction of non-local variables.
> 
> I propose this is an editorial change, as it just documents current practice
> rather than suggesting a change to current practice. As such, the normal
> HotSpot PR process applies.
> 
> The updated .html file was generated using make update-build-docs.

doc/hotspot-style.md line 776:

> 774: 
> 775: Avoid variables with static storage duration and non-constant initialization,
> 776: or with non-trivial destruction.  Such variables can lead to the so-called

I wonder about the phrase "non-constant". There are a few places where we set up static objects that are non-constant, but doesn't depend on anything. For example, `ZGC_ONLY(static ZArguments          zArguments;)
`. Is `non-constant` precise enough to describe what we want to prevent?

doc/hotspot-style.md line 777:

> 775: Avoid variables with static storage duration and non-constant initialization,
> 776: or with non-trivial destruction.  Such variables can lead to the so-called
> 777: "static initialization order fiasco", or its dual on the destruction size.

What does `destruction size` mean here? Or did you intend to write "destruction site"?

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PR Review Comment: https://git.openjdk.org/jdk/pull/25812#discussion_r2149301958
PR Review Comment: https://git.openjdk.org/jdk/pull/25812#discussion_r2149289222