Class: Spawn

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

Constant Summary collapse

RAILS_1_x = 
nil
RAILS_2_2 = 
nil
RAILS_3_x = 
nil
@@default_options = 
{
  # default to forking (unless windows or jruby)
  :method => ((RUBY_PLATFORM =~ /(win32|mingw32|java)/) ? :thread : :fork),
  :nice   => nil,
  :kill   => false,
  :argv   => nil
}
@@resources =

things to close in child process

[]
@@punks =

forked children to kill on exit

[]
@@logger =

in some environments, logger isn’t defined

defined?(::Rails) ? ::Rails.logger : ::Logger.new(STDERR)

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(opts = {}) ⇒ Spawn

Spawns a long-running section of code and returns the ID of the spawned process. By default the process will be a forked process. To use threading, pass :method => :thread or override the default behavior in the environment by setting ‘Spawn::method :thread’.



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# File 'lib/spawn.rb', line 93

def initialize(opts = {})
  raise "Must give block of code to be spawned" unless block_given?
  options = @@default_options.merge(symbolize_options(opts))
  # setting options[:method] will override configured value in default_options[:method]
  if options[:method] == :yield
    yield
  elsif options[:method].respond_to?(:call)
    options[:method].call(proc { yield })
  elsif options[:method] == :thread
    # for versions before 2.2, check for allow_concurrency
   if RAILS_2_2 || ActiveRecord::Base.respond_to?(:allow_concurrency) ?
        ActiveRecord::Base.allow_concurrency :  Rails.application.config.allow_concurrency
     @type = :thread
     @handle = thread_it(options) { yield }
    else
      @@logger.error("spawn(:method=>:thread) only allowed when allow_concurrency=true")
      raise "spawn requires config.active_record.allow_concurrency=true when used with :method=>:thread"
    end
  else
    @type = :fork
    @handle = fork_it(options) { yield }
  end
end

Instance Attribute Details

#handle ⇒ Object

Returns the value of attribute handle.



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# File 'lib/spawn.rb', line 32

def handle
  @handle
end

#type ⇒ Object

Returns the value of attribute type.



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# File 'lib/spawn.rb', line 31

def type
  @type
end

Class Method Details

.alive?(pid) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/spawn.rb', line 64

def self.alive?(pid)
  begin
    Process::kill 0, pid
    # if the process is alive then kill won't throw an exception
    true
  rescue Errno::ESRCH
    false
  end
end

.close_resources ⇒ Object

close all the resources added by calls to resource_to_close



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# File 'lib/spawn.rb', line 56

def self.close_resources
  @@resources.each do |resource|
    resource.close if resource && resource.respond_to?(:close) && !resource.closed?
  end
  # in case somebody spawns recursively
  @@resources.clear
end

.default_options(options = {}) ⇒ Object

Set the options to use every time spawn is called unless specified otherwise. For example, in your environment, do something like this:

Spawn::default_options = {:nice => 5}

to default to using the :nice option with a value of 5 on every call. Valid options are:

:method => (:thread | :fork | :yield)
:nice   => nice value of the forked process
:kill   => whether or not the parent process will kill the
           spawned child process when the parent exits
:argv   => changes name of the spawned process as seen in ps



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# File 'lib/spawn.rb', line 45

def self.default_options(options = {})
  @@default_options.merge!(options)
  @@logger.info "spawn> default options = #{options.inspect}" if @@logger
end

.kill_punks ⇒ Object 



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# File 'lib/spawn.rb', line 74

def self.kill_punks
  @@punks.each do |punk|
    if alive?(punk)
      @@logger.info "spawn> parent(#{Process.pid}) killing child(#{punk})" if @@logger
      begin
        Process.kill("TERM", punk)
      rescue
      end
    end
  end
  @@punks = []
end

.resources_to_close(*resources) ⇒ Object

set the resources to disconnect from in the child process (when forking)



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# File 'lib/spawn.rb', line 51

def self.resources_to_close(*resources)
  @@resources = resources
end

.wait(sids = []) ⇒ Object 



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# File 'lib/spawn.rb', line 117

def self.wait(sids = [])
  # wait for all threads and/or forks (if a single sid passed in, convert to array first)
  Array(sids).each do |sid|
    if sid.type == :thread
      sid.handle.join()
    else
      begin
        Process.wait(sid.handle)
      rescue
        # if the process is already done, ignore the error
      end
    end
  end
  # clean up connections from expired threads
  ActiveRecord::Base.verify_active_connections!() if defined?(ActiveRecord)
end