option to specify vcpu runtime constraints on arvados-cwl-runner when using --submit
It is great that a-c-r now has the --thread-count option to do some multithreaded operations. However, in our environment, we run a-c-r with --submit and we also enforce vcpu limits using cgroups. Currently, a-c-r does not specify a vcpu limit on the RunnerContainer container request that it submits, which means that it defaults to 1 vcpu. Therefore, regardless of what --thread-count option we specify, the threads are all forced to share a single vcpu.
I would propose to add a --submit-runner-vcpus argument to a-c-r (default: 1 as it is now) that allows one to specify the vcpus runtime constraint that will be included with the RunnerContainer container request, so that we can make full use of the new --thread-count option.