On a 12-thread machine, building https://github.com/google/google-authenticator-android with --persistent_android_resource_processor and aapt2 spawns 23 JVM workers:

$ ps -ef | grep java.*ResourceProcessorBusyBox.*persistent_worker | wc -l
23

We should cap the number of workers for the resource processor to reduce OOM risks, especially for large builds.