Fixed the WorkerPool [demos]
Fixed the WorkerPool [demos]


Former-commit-id: 8ed4bfd4197f7add279176c60aa6a965ce0e4ea7 [formerly 3c57e9055a6cc27b2c35b06ffde5139e3b58dfc3]
Former-commit-id: b7bf3de9d30f87b627821382843f760c004caf3d
gem/oq-engine,gem/oq-engine,gem/oq-engine,gem/oq-engine,gem/oq-engine