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Forking Processes In Ruby On Rails
# Logic for forking connections
# The forked process does not have access to static vars as far as I can discern, so I've done some stuff to check if the op threw an exception.
def fork_with_new_connection
# Store the ActiveRecord connection information
config = ActiveRecord::Base.remove_connection
pid = fork do
# tracking if the op failed for the Process exit
success = true
begin
ActiveRecord::Base.establish_connection(config)
# This is needed to re-initialize the random number generator after forking (if you want diff random numbers generated in the forks)
srand
# Run the closure passed to the fork_with_new_connection method
yield
rescue Exception => exception
puts ("Forked operation failed with exception: #{exception}")
# the op failed, so note it for the Process exit
success = false
ensure
ActiveRecord::Base.remove_connection
Process.exit! success
end
end
# Restore the ActiveRecord connection information
ActiveRecord::Base.establish_connection(config)
#return the process id
pid
end
# A static var to keep track of the number of failures
@@failed = 0
@@forks = 20
#forks @@forks processes
def concurrent_opps iteration
(1..@@forks).each do |i|
pid = fork_with_new_connection do
# simple way to keep track of progress
puts "Fork: #{i}"
#necessary to manage activerecord connections since we are forking
ActiveRecord::Base.connection.reconnect!
#
# The whole reason for creating the fork... do some stuff here
#
x = rand[25]
if 0==x then raise Exception, "it was 6, and I don't like 6's" end
end
puts "Process #{pid} completed"
end
#Wait for all processes to finish before proceeding - collect results as well
results = Process.waitall
results.each{ |result|
@@failed += result[1].exitstatus
}
end
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