[Buildroot] [PATCH v2] qt5webengine: propagate parallel flag to ninja

[Yann E. MORIN <yann.morin.1998@free.fr>]

Ga?l, All,

On 2018-06-29 10:35 -0400, Ga?l PORTAY spake thusly:
> WebEngine is a big project to build. It uses ninja which is a build
> system that does everything in parallel[1].
> 
> 	Builds are always run in parallel, based by default on the number of
> 	CPUs your system has. Underspecified build dependencies will result in
> 	incorrect builds.
> 
> QtWebEngine does not propagate the parallel flag from the running
> instance of make to ninja. Thus, all the machine cores are used to build
> this single project.
> 
> 	make -j 10 -> ninja -j # all cores
> 
> This behavior disrupts powerful machines which are setup to build many
> projects in parallel. Even worse, the build fails on machines where the
> ratio CPU-cores / amount of RAM (including swap) is not appropriate. g++
> may have not enough of memory to build all those files in parallel.
> 
> Unfortunatly, the target `run_ninja' is hardcoded in the Makefile
> src/core/Makefile.run_gn; there is no way to propagate flags using a
> variable through the make command-line.
> 
> 	run_ninja:
> 	        /home/gportay/src/buildroot/output-qt5.11/build/qt5webengine-5.11.1/src/3rdparty/ninja/ninja
> -C /home/gportay/src/buildroot/output-qt5.11/build/qt5webengine-5.11.1/src/core/release QtWebEngineCore
> 
> Luckily, the Qt gn_run.pro[2] can hardcode ninja extra flags through the
> variable NINJAFLAGS when the Makefile is generated (which is performed
> during the build and not during configure step).
> 
> This commit sets the NINJAFLAGS using the variable PARALLEL_JOBS to limit
> the number of cores used by ninja.
> 
> Fixes:
> 	virtual memory exhausted: Cannot allocate memory
> 
> [1]: https://ninja-build.org/manual.html#_comparison_to_make
> [2]: https://github.com/qt/qtwebengine/blob/v5.11.1/src/core/gn_run.pro#L49-L53
> 
> CC: Damien Riegel <damien.riegel@savoirfairelinux.com>
> CC: Jean-Fran?ois T?tu <jean-francois.tetu@savoirfairelinux.com>
> Signed-off-by: Ga?l PORTAY <gael.portay@savoirfairelinux.com>

Acked-by: "Yann E. MORIN" <yann.morin.1998@free.fr>

Regards,
Yann E. MORIN.

> ---
> Changes since v1:
>  - Use PARALLEL_JOBS instead of BR2_JLEVEL
>  - Reword commit message
> 
>  package/qt5/qt5webengine/qt5webengine.mk | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/package/qt5/qt5webengine/qt5webengine.mk b/package/qt5/qt5webengine/qt5webengine.mk
> index 08120421d6..2c622c91ba 100644
> --- a/package/qt5/qt5webengine/qt5webengine.mk
> +++ b/package/qt5/qt5webengine/qt5webengine.mk
> @@ -48,6 +48,8 @@ define QT5WEBENGINE_PYTHON2_SYMLINK
>  endef
>  QT5WEBENGINE_PRE_CONFIGURE_HOOKS += QT5WEBENGINE_PYTHON2_SYMLINK
>  
> +QT5WEBENGINE_ENV += NINJAFLAGS="-j$(PARALLEL_JOBS)"
> +
>  ifeq ($(BR2_PACKAGE_QT5_VERSION_LATEST),y)
>  define QT5WEBENGINE_CREATE_HOST_PKG_CONFIG
>  	sed s%@HOST_DIR@%$(HOST_DIR)%g $(QT5WEBENGINE_PKGDIR)/host-pkg-config.in > $(@D)/host-bin/host-pkg-config
> -- 
> 2.17.1
> 
> _______________________________________________
> buildroot mailing list
> buildroot at busybox.net
> http://lists.busybox.net/mailman/listinfo/buildroot

-- 
.-----------------.--------------------.------------------.--------------------.
|  Yann E. MORIN  | Real-Time Embedded | /"\ ASCII RIBBON | Erics' conspiracy: |
| +33 662 376 056 | Software  Designer | \ / CAMPAIGN     |  ___               |
| +33 223 225 172 `------------.-------:  X  AGAINST      |  \e/  There is no  |
| http://ymorin.is-a-geek.org/ | _/*\_ | / \ HTML MAIL    |   v   conspiracy.  |
'------------------------------^-------^------------------^--------------------'