What is Wall clock in maven build

Question

When I build my project using threads

i.e mvn -T 4 install -Dmaven.test.skip=true

I am getting like

Total Time: 10:17.623s (Wall Clock)

What is meant by Wall clock here? When I build normally I am not getting that word. I searched, but I am unable to find the information.

Thanks in advance.

Answer 1

By default (without -T 4), Maven builds all modules sequentially rather than in parallel. So you only have one process, which (in your example) takes 40s.

You start the build with 4 threads, so the total time of 40s gets divided by 4 threads, so each thread runs for 10s.

The total CPU time stays the same (40s), but the time that passed for YOU is only 10s + some overhead for parallelization. It's the time that you see when you look on your clock on the wall, therefore it's called Wall-Clock time.