Class: Thread::Pool

Inherits:
Object
  • Object
show all
Defined in:
lib/thread/pool.rb,
lib/thread/future.rb

Overview

A pool is a container of a limited amount of threads to which you can add tasks to run.

This is usually more performant and less memory intensive than creating a new thread for every task.

Defined Under Namespace

Classes: Task

Class Attribute Summary collapse

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(min, max = nil, &block) ⇒ Pool

Create the pool with minimum and maximum threads.

The pool will start with the minimum amount of threads created and will spawn new threads until the max is reached in case of need.

A default block can be passed, which will be used to #process the passed data.



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# File 'lib/thread/pool.rb', line 113

def initialize (min, max = nil, &block)
  @min   = min
  @max   = max || min
  @block = block

  @cond  = ConditionVariable.new
  @mutex = Mutex.new

  @done       = ConditionVariable.new
  @done_mutex = Mutex.new

  @todo     = []
  @workers  = []
  @timeouts = {}

  @spawned       = 0
  @waiting       = 0
  @shutdown      = false
  @trim_requests = 0
  @auto_trim     = false
  @idle_trim     = nil

  @mutex.synchronize {
    min.times {
      spawn_thread
    }
  }
end

Class Attribute Details

.abort_on_exception ⇒ Object

If true, tasks will allow raised exceptions to pass through.

Similar to Thread.abort_on_exception



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# File 'lib/thread/pool.rb', line 350

def abort_on_exception
  @abort_on_exception
end

Instance Attribute Details

#max ⇒ Object (readonly)

Returns the value of attribute max.



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# File 'lib/thread/pool.rb', line 104

def max
  @max
end

#min ⇒ Object (readonly)

Returns the value of attribute min.



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# File 'lib/thread/pool.rb', line 104

def min
  @min
end

#spawned ⇒ Object (readonly)

Returns the value of attribute spawned.



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# File 'lib/thread/pool.rb', line 104

def spawned
  @spawned
end

#waiting ⇒ Object (readonly)

Returns the value of attribute waiting.



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# File 'lib/thread/pool.rb', line 104

def waiting
  @waiting
end

Instance Method Details

#auto_trim! ⇒ Object

Enable auto trimming, unneeded threads will be deleted until the minimum is reached.



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# File 'lib/thread/pool.rb', line 152

def auto_trim!
  @auto_trim = true
end

#auto_trim? ⇒ Boolean

Check if auto trimming is enabled.

Returns:

  • (Boolean) 


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# File 'lib/thread/pool.rb', line 146

def auto_trim?
  @auto_trim
end

#backlog ⇒ Object

Get the amount of tasks that still have to be run.



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# File 'lib/thread/pool.rb', line 186

def backlog
  @mutex.synchronize {
    @todo.length
  }
end

#done? ⇒ Boolean

Are all tasks consumed ?

Returns:

  • (Boolean) 


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# File 'lib/thread/pool.rb', line 193

def done?
  @mutex.synchronize {
    @todo.empty? and @waiting == @spawned
  }
end

#future(&block) ⇒ Object 



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# File 'lib/thread/future.rb', line 161

def future (&block)
  Thread.future self, &block
end

#idle(*args, &block) ⇒ Object

Process Block when there is a idle worker if not block its returns



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# File 'lib/thread/pool.rb', line 217

def idle (*args, &block)
  while !idle?
    @done_mutex.synchronize {
      break if idle?
      @done.wait @done_mutex
    }
  end

  unless block
    return
  end

  process *args, &block
end

#idle? ⇒ Boolean

Check if there are idle workers.

Returns:

  • (Boolean) 


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# File 'lib/thread/pool.rb', line 210

def idle?
  @mutex.synchronize {
    @todo.length < @waiting
  }
end

#idle_trim!(timeout) ⇒ Object

Enable idle trimming. Unneeded threads will be deleted after the given number of seconds of inactivity. The minimum number of threads is respeced.



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# File 'lib/thread/pool.rb', line 168

def idle_trim!(timeout)
  @idle_trim = timeout
end

#idle_trim? ⇒ Boolean

Check if idle trimming is enabled.

Returns:

  • (Boolean) 


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# File 'lib/thread/pool.rb', line 162

def idle_trim?
  !@idle_trim.nil?
end

#join ⇒ Object

Join on all threads in the pool.



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# File 'lib/thread/pool.rb', line 312

def join
  until @workers.empty?
    if worker = @workers.first
      worker.join
    end
  end

  self
end

#no_auto_trim! ⇒ Object

Disable auto trimming.



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# File 'lib/thread/pool.rb', line 157

def no_auto_trim!
  @auto_trim = false
end

#no_idle_trim! ⇒ Object

Turn of idle trimming.



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# File 'lib/thread/pool.rb', line 173

def no_idle_trim!
  @idle_trim = nil
end

#process(*args, &block) ⇒ Object Also known as: <<

Add a task to the pool which will execute the block with the given argument.

If no block is passed the default block will be used if present, an ArgumentError will be raised otherwise.



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# File 'lib/thread/pool.rb', line 237

def process (*args, &block)
  unless block || @block
    raise ArgumentError, 'you must pass a block'
  end

  task = Task.new(self, *args, &(block || @block))

  @mutex.synchronize {
    raise 'unable to add work while shutting down' if shutdown?

    @todo << task

    if @waiting == 0 && @spawned < @max
      spawn_thread
    end

    @cond.signal
  }

  task
end

#resize(min, max = nil) ⇒ Object

Resize the pool with the passed arguments.



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# File 'lib/thread/pool.rb', line 178

def resize (min, max = nil)
  @min = min
  @max = max || min

  trim!
end

#shutdown ⇒ Object

Shut down the pool, it will block until all tasks have finished running.



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# File 'lib/thread/pool.rb', line 292

def shutdown
  @mutex.synchronize {
    @shutdown = :nicely
    @cond.broadcast
  }

  join

  if @timeout
    @shutdown = :now

    wake_up_timeout

    @timeout.join
  end

  self
end

#shutdown! ⇒ Object

Shut down the pool instantly without finishing to execute tasks.



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# File 'lib/thread/pool.rb', line 280

def shutdown!
  @mutex.synchronize {
    @shutdown = :now
    @cond.broadcast
  }

  wake_up_timeout

  self
end

#shutdown? ⇒ Boolean

Check if the pool has been shut down.

Returns:

  • (Boolean) 


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# File 'lib/thread/pool.rb', line 143

def shutdown?; !!@shutdown; end

#shutdown_after(timeout) ⇒ Object

Shutdown the pool after a given amount of time.



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# File 'lib/thread/pool.rb', line 336

def shutdown_after (timeout)
  Thread.new {
    sleep timeout

    shutdown
  }

  self
end

#timeout_for(task, timeout) ⇒ Object

Define a timeout for a task.



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# File 'lib/thread/pool.rb', line 323

def timeout_for (task, timeout)
  unless @timeout
    spawn_timeout_thread
  end

  @mutex.synchronize {
    @timeouts[task] = timeout

    wake_up_timeout
  }
end

#trim(force = false) ⇒ Object

Trim the unused threads, if forced threads will be trimmed even if there are tasks waiting.



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# File 'lib/thread/pool.rb', line 263

def trim (force = false)
  @mutex.synchronize {
    if (force || @waiting > 0) && @spawned - @trim_requests > @min
      @trim_requests += 1
      @cond.signal
    end
  }

  self
end

#trim! ⇒ Object

Force ##trim.



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# File 'lib/thread/pool.rb', line 275

def trim!
  trim true
end

#wait_done ⇒ Object

Wait until all tasks are consumed. The caller will be blocked until then.



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# File 'lib/thread/pool.rb', line 200

def wait_done
  loop do
    @done_mutex.synchronize {
      return self if done?
      @done.wait @done_mutex
    }
  end
end