You can see my buildscript repository for scripts which can help you a lot.
This is the patch to fix the out of memory heap error.
It occurs mainly during the compilation of Metalava.
To fix this error run these commands in the source of the rom [xxx@linux:/home/customrom/lineageos]
cd build/soong && git fetch https://github.com/nparashar150/android_build_soong && git cherry-pick c8ba7af59acda55a16835727d1d351b8d58a5ca4
Now after cherry picking you need other patches and configurations.
If you want to autoconfigure zram copy paste this
sudo apt install zram-config
Then after this type this command and just put a # in front of swap if u have a swap partition or if you have a swap file you can just ignore it
sudo nano /etc/fstab
Installing ZRAM Open the terminal create the zram.conf file
sudo nano /etc/modules-load.d/zram.conf
Paste this inside the file zram.conf and save and exit
zram
Create another new file
sudo nano /etc/modprobe.d/zram.conf
Paste this inside the file zram.conf and save and exit
options zram num_devices=1
For configuring the size of the ZRAM create new file
sudo nano /etc/udev/rules.d/99-zram.rules
Paste this inside the file and currently I will suggest the size to be 8Gib but you can increase if you want.
KERNEL=="zram0", ATTR{disksize}="8192M",TAG+="systemd"
After this the ZRAM is created but its better if you disable traditional swap
Open the terminal and edit the fstab file and put a # in the line of swap.
sudo nano /etc/fstab
# swap was on /dev/sda7 during installation
#UUID=5ad493cf-6f4a-42ab-9b41-7f6bf9167b3e none swap sw 0>
Something like that will be the output.
In order to run ZRAM you need to create a system unit file.
sudo nano /etc/systemd/system/zram.service
Add these lines inside the file.
[Unit]
Description=Swap with zram
After=multi-user.target
[Service]
Type=oneshot
RemainAfterExit=true
ExecStartPre=/sbin/mkswap /dev/zram0
ExecStart=/sbin/swapon /dev/zram0
ExecStop=/sbin/swapoff /dev/zram0
[Install]
WantedBy=multi-user.target
Save and close it.
To enable the ZRAM run this
sudo systemctl enable zram
Reboot your system and ZRAM is created xD.
Now to check if ZRAM is working run this.
cat /proc/swaps
And you will see zram like this
/dev/zram0 partition 8388604 538860 -2
Now dont forget to restar your computer
Add this to your build command so that Metalava compiles first
. build/envsetup.sh && lunch <codename>_<devicename>-userdebug && make api-stubs-docs && m/make bacon
Good Luck I hope the Android R build you are trying to build compiles now.