Multi-core assembly in debian stretch

[isopen]

You should not experiment with fewer cores.

Debian stretch. I have 8 cores in my car.

I did the following:
zlib from the source code https://packages.debian.org/source/stretch/zlib
apt install libssl-dev libreadline-dev ccache
other packages according to the instructions

first step:
mkdir build
cd build
cmake ..
cmake --build . (at this step I was dejected)
ctrl+c

second step
make -j 6
the virtual machine hangs. restarting the virtual machine.

third step
make -j 4
cautiously somewhere in the middle the system ceases to hang and everything is going to.
just in case cmake --build .

Do not forget about the ccache package for subsequent assemblies useful.
Then you can cmake --build .

Are we going to collect in several cores or will we wait a long time in one core according to the instructions?

[arseny30]

It probably hangs because all RAM is used. You may try clang instead of g++, it uses much less memory than g++ and compiles TDLib quicker.

Also cmake -GNinja .. will use ninja instead of make. ninja will try to determine needed number concurrent jobs by itself, so simple cmake --build . will be enough to run a build as fast as possible.

[isopen]

Ok :)

apt install ninja-build
cmake -GNinja ..
cmake --build .

Accordingly, the virtual machine hung.
Something went wrong...+ eats 10gb of ozu.
The effect is similar to make -j 6

apt install clang
CXX=clang++ CC=clang cmake ..
cmake --build . (the effect is the same as g ++)

make -j 4 although it hangs in the middle of the assembly, but collects in all cases faster :) for simple reasons.

[arseny30]

Ok, ninja won't help here. But it still looks that you just have not enough RAM for concurrent build. Am I right?

[isopen]

I do not have much RAM, but there is 16gb ozu.)
Library at assembly is eating nenuchutku. And all resources in general.
I may be in something I do not understand, but it's a kapets.
In 4 cores going 20+ minutes. eats whole RAM.

The moment that in our market most have only 8GB of RAM and 4 cores :))

All CPU time fills the ninja in the first place.

64GB RAM is what you need?)

[levlam]

4 GB of RAM should be enough for GCC (at least for Release builds). Clang usually needs only 1,5-2 GB of RAM for each file. You need to adjust job count to not use more RAM than available in the system. It is strange that modern C++ compilers are so slow and need so much RAM to compile simple source files, but it is not a library issue.

[isopen]

@levlam thank

[isopen]

Nevertheless, if you do not mind, we will continue.

Assembly on 4 cores of 8 and almost 9GB of RAM

• Further all ok (1,5-3 GB)

• At this point, the assembly eats about 5GB

• Further all ok (1,5-3 GB)

• At this place begins to eat the whole RAM

• Accordingly, the operating system hangs for a while.

Building CXX object CMakeFiles/tdcore.dir/td/telegram/Payments.cpp.o

• Further all ok (1,5-3 GB)