capture worker node counts at the start of the execute phase
capture worker node counts at the start of the execute phase


Former-commit-id: bf1af930ff426d1bbc9ef8f6a1cb521b96dc7ce4 [formerly 187d655e53695980afb6c3544fc62bd3b10bc1b1]
Former-commit-id: 3920615369f1d0243ec86756ca3acfa571d930fb
gem/oq-engine,gem/oq-engine,gem/oq-engine,gem/oq-engine,gem/oq-engine