Class: Loops::ProcessManager

Inherits:
Object
  • Object
show all
Defined in:
lib/loops/process_manager.rb

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(config, logger) ⇒ ProcessManager

Returns a new instance of ProcessManager.



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# File 'lib/loops/process_manager.rb', line 5

def initialize(config, logger)
  @config = {
    'poll_period' => 1,
    'wait_period' => 10,
    'workers_engine' => 'fork',
  }.merge(config)

  @logger = logger
  @worker_pools = {}
  @shutdown = false
end

Instance Attribute Details

#logger ⇒ Object (readonly)

Returns the value of attribute logger.



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# File 'lib/loops/process_manager.rb', line 3

def logger
  @logger
end

Instance Method Details

#monitor_workers ⇒ Object 



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# File 'lib/loops/process_manager.rb', line 30

def monitor_workers
  setup_signals

  logger.info('Starting workers monitoring code...')
  loop do
    logger.debug("Checking workers' health...")
    @worker_pools.each do |name, pool|
      break if shutdown?
      pool.check_workers
    end

    break if shutdown?
    logger.debug("Sleeping for #{@config['poll_period']} seconds...")
    sleep(@config['poll_period'])
  end
ensure
  logger.info("Workers monitoring loop is finished, starting shutdown...")
  # Send out stop signals
  stop_workers(false)

  # Wait for all the workers to die
  unless wait_for_workers(@config['wait_period'])
    logger.info("Some workers are still alive after 10 seconds of waiting. Killing them...")
    stop_workers(true)
    wait_for_workers(5)
  end
end

#setup_signals ⇒ Object 



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# File 'lib/loops/process_manager.rb', line 58

def setup_signals
  # Zombie reapers
  trap('CHLD') {}
  trap('EXIT') {}
end

#shutdown? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/loops/process_manager.rb', line 95

def shutdown?
  @shutdown
end

#start_shutdown! ⇒ Object 



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# File 'lib/loops/process_manager.rb', line 99

def start_shutdown!
  logger.info("Starting shutdown (shutdown flag set)...")
  @shutdown = true
end

#start_workers(name, number, &blk) ⇒ Object

Raises:

  • (ArgumentError) 


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# File 'lib/loops/process_manager.rb', line 22

def start_workers(name, number, &blk)
  raise ArgumentError, "Need a worker block!" unless block_given?

  logger.debug("Creating a workers pool of #{number} workers for #{name} loop...")
  @worker_pools[name] = Loops::WorkerPool.new(name, self, @config['workers_engine'], &blk)
  @worker_pools[name].start_workers(number)
end

#stop_workers(force = false) ⇒ Object 



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# File 'lib/loops/process_manager.rb', line 85

def stop_workers(force = false)
  # Set shutdown flag
  logger.info("Stopping workers#{force ? ' (forced)' : ''}...")

  # Termination loop
  @worker_pools.each do |name, pool|
    pool.stop_workers(force)
  end
end

#update_wait_period(period) ⇒ Object 



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# File 'lib/loops/process_manager.rb', line 17

def update_wait_period(period)
  return unless period
  @config['wait_period'] = [@config['wait_period'], period].max
end

#wait_for_workers(seconds) ⇒ Object 



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# File 'lib/loops/process_manager.rb', line 64

def wait_for_workers(seconds)
  seconds.times do
    logger.info("Shutting down... waiting for workers to die (we have #{seconds} seconds)...")
    running_total = 0

    @worker_pools.each do |name, pool|
      running_total += pool.wait_workers
    end

    if running_total.zero?
      logger.info("All workers are dead. Exiting...")
      return true
    end

    logger.info("#{running_total} workers are still running! Sleeping for a second...")
    sleep(1)
  end

  return false
end