# Execute $(1) with each entry of $(2) as variable "arg" in parallel, $(3) seconds timeout
# ex $(call _parallel,some_parallel_task $$arg,apple pear orange,10)
# will execute
#   some_parallel_task apple
#   some_parallel_task pear
#   some_parallel_task orange
# in parallel each with a timeout for 10 seconds, and await completion
define _parallel
	@rm -rf .parallel.pids
	@$(foreach arg,$(2), \
          arg=$(arg); \
          timeout $(3)s $(1) & \
          echo $$! >> .parallel.pids; \
        ) \
        while read pid; do \
          wait $$pid; \
        done <.parallel.pids
	@rm -rf .parallel.pids
endef