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

[Kevin Rushforth]

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.

I'll run this through or CI as well as do some local builds. The one concern I have is that `NUM_COMPILE_THREADS` is set to 1 on macOS, meaning that this will increase the build time on macOS.

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PR Comment: https://git.openjdk.org/jfx/pull/1554#issuecomment-2326627374