RFR: 8339335: set number of parallel jobs when building webkit

[Johan Vos]

On Mon, 2 Sep 2024 07:20:50 GMT, Johan Vos <jvos at openjdk.org> wrote:

> When building webkit, the perl script in `modules/javafx.web/src/main/native/Tools/Scripts/build-webkit` will check for a `-j` argument in `$makeArgs`. If that doesn't exist, it will default to `numberOfCPUs()`.
> This PR passes the `NUM_COMPILE_THREADS` from `build.gradle` to the `build-webkit` script. When not setting `NUM_COMPILE_THREADS` explicitly,it will default to the number of CPU's as well, hence it will have the same behavior as without this PR.
> When setting `NUM_COMPILE_THREADS` explicitly, the provided number will be used by cmake as well now.

It is easy to create (yet) another property for this, but that will make the already complicated build.gradle even more complicated, so if possible I'd like to avoid that.

I read the cryptic comment in build.gradle
`// On Mac we limit it to 1 by default due to problems running gcc in parallel`
What is the problem that is being referred to here? And why would that problem occur in the other native compile jobs but not in the (resource intensive) webkit compile jobs?

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PR Comment: https://git.openjdk.org/jfx/pull/1554#issuecomment-2326652996