Compiling QtWebEngine fails because out of memory

odelaune

Hello, I try to compile the QtWebEngine module of Qt 6.4.2 from sources but I fail because I do not have enough memory. I have a Intel i5-10505 processor with 12 threads and 24 Go of RAM. It seems that I have not enough RAM compare to the number of threads.

I have read this post but I cannot use this solution because I do not have sudo rights to use chcpu.

So I am looking for solution that works with only user right. Basically, I think limiting the number of ninja jobs is enough but I do not find how to do it.

Thanks in advance for your help.

jsulm

@odelaune Reduce amount of parallel build processes

odelaune

@jsulm Indeed, but the question is how?

jsulm

@odelaune How do you build? Using make? Using ninja? ...?

odelaune

@jsulm

According to this, here is what I tried so far:

tar -xvf qt-everywhere-src-6.4.2.tar.xz
cd qt-everywhere-src-6.4.2/
./configure -prefix /home/odelaune/Qt/6.4.2src -DQT_FEATURE_webengine_jumbo_build=OFF -DINPUT_webengine_jumbo_file_merge_limit=0

Note that -DQT_FEATURE_webengine_jumbo_build and -DINPUT_webengine_jumbo_file_merge_limit=0 seems to be ignored because here is the ouput of configure

WebEngine Repository Build Options:
Build Ninja ............................ no
Build Gn ............................... yes
Jumbo Build ............................ yes
Developer build ........................ no
Build QtWebEngine Modules:
Build QtWebEngineCore ................ yes
Build QtWebEngineWidgets ............. yes
Build QtWebEngineQuick ............... yes

jsulm

@odelaune I mean how do you start the actual build?

odelaune

@jsulm

cmake --build . -- -j4

But the problem is ninja that is used to compile QtWebEngine does not care about "-j4" and uses all cpus that are available.

jsulm

@odelaune Did you check whether you can tell configure to not to use ninja?

odelaune

@jsulm I had a look but I could not find how to do.

CompSciDude

@odelaune The way you are providing the arguments is incorrect. Qt's configure script has two arguments of interest when dealing with jumbo-build. One is -webengine-jumbo-build, which toggles jumbo-build (prepend -no to the argument to disable jumbo-build). Two is --webengine-jumbo-build=<number>, which determines how many source files comprise each jumbo source file.

CompSciDude

@odelaune The way to specify the number of processors to Ninja is to set the NINJAFLAGS environment variable with -j<number>. For example, if I want Ninja to use 8 processes, i do export NINJAFLAGS=-j8.

CompSciDude

I ran into a similar issue while building Qt 6.2.4. g++ would terminate unexpectedly. I assume it ran out of memory. Just to be sure it was not Qt-relates, I opened an issue https://bugreports.qt.io/plugins/servlet/mobile#issue/QTBUG-115083.

ytexas

@CompSciDude
I tried -no-webengine-jumbo-build when building Qt 6.7.2, still cannot build cause by out of memory (12 G RAM). Neither --webengine-jumbo-build=<number>

Marcky

@CompSciDude works for me! (yocto with Qt6.7.3)

Added this to a qtwebengine_git.bbappend:

export NINJAFLAGS="-j<proper value for your setup>"

Thanks!