How to use all CPU cores/threads when running Android Studio gradle build?

TL; DR

According to Gradle Build Environment Documentation:

org.gradle.configureondemand=true
org.gradle.daemon=true
org.gradle.parallel=true
org.gradle.workers.max=4             

Details

By default org.gradle.workers.max is set to the number of CPU processors (in my case 8).

Since my Android Studio was freezing my Ubuntu workstation (sometimes forcing me to hard reset the computer), I have set it to 4, ensuring my workstation will not starve on CPU and memory.

Update for accepted answer:

Since gradle uses Worker API you need to use

org.gradle.workers.max

instead of

org.gradle.parallel.threads

Link to the doc

in the local.properties file in my project I have

org.gradle.daemon=true
org.gradle.parallel=true
org.gradle.configureondemand=true

additionally you can specify

org.gradle.parallel.threads

which specifies the maximum number of threads to use for parallel execution. it needs org.gradle.parallel=true. Here you can find more information about it