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 124

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 346

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 115

def max
  @max
end

#min ⇒ Object (readonly)

Returns the value of attribute min.



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# File 'lib/thread/pool.rb', line 115

def min
  @min
end

#spawned ⇒ Object (readonly)

Returns the value of attribute spawned.



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# File 'lib/thread/pool.rb', line 115

def spawned
  @spawned
end

#waiting ⇒ Object (readonly)

Returns the value of attribute waiting.



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# File 'lib/thread/pool.rb', line 115

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 165

def auto_trim!
  @auto_trim = true

  self
end

#auto_trim? ⇒ Boolean

Check if auto trimming is enabled.

Returns:

  • (Boolean) 


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# File 'lib/thread/pool.rb', line 159

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 207

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 214

def done?
  @mutex.synchronize {
    _done?
  }
end

#future(&block) ⇒ Object 



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# File 'lib/thread/future.rb', line 174

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

#idle? ⇒ Boolean

Check if there are idle workers.

Returns:

  • (Boolean) 


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# File 'lib/thread/pool.rb', line 246

def idle?
  @mutex.synchronize {
    _idle?
  }
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 185

def idle_trim!(timeout)
  @idle_trim = timeout

  self
end

#idle_trim? ⇒ Boolean

Check if idle trimming is enabled.

Returns:

  • (Boolean) 


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# File 'lib/thread/pool.rb', line 179

def idle_trim?
  !@idle_trim.nil?
end

#no_auto_trim! ⇒ Object

Disable auto trimming.



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# File 'lib/thread/pool.rb', line 172

def no_auto_trim!
  @auto_trim = false

  self
end

#no_idle_trim! ⇒ Object

Turn of idle trimming.



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# File 'lib/thread/pool.rb', line 192

def no_idle_trim!
  @idle_trim = nil

  self
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 257

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 199

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 312

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

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

  if @timeout
    @shutdown = :now

    wake_up_timeout

    @timeout.join
  end
end

#shutdown! ⇒ Object

Shut down the pool instantly without finishing to execute tasks.



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# File 'lib/thread/pool.rb', line 300

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 154

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 334

def shutdown_after(timeout)
  Thread.new {
    sleep timeout

    shutdown
  }
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 283

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 295

def trim!
  trim true
end

#wait(what = :idle) ⇒ Object

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



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# File 'lib/thread/pool.rb', line 221

def wait(what = :idle)
  case what
  when :done
    until done?
      @done_mutex.synchronize {
        break if _done?

        @done.wait @done_mutex
      }
    end

  when :idle
    until idle?
      @done_mutex.synchronize {
        break if _idle?

        @done.wait @done_mutex
      }
    end
  end

  self
end