Class: Qless::Pool

Inherits:
Object
  • Object
show all
Extended by:
Logging
Includes:
Logging
Defined in:
lib/qless/pool.rb,
lib/qless/pool/cli.rb,
lib/qless/pool/logging.rb,
lib/qless/pool/version.rb,
lib/qless/pool/pooled_worker.rb

Defined Under Namespace

Modules: CLI, Logging, PooledWorker Classes: QuitNowException

Constant Summary collapse

SIG_QUEUE_MAX_SIZE = 
5
DEFAULT_WORKER_INTERVAL = 
5
QUEUE_SIGS = 
[ :QUIT, :INT, :TERM, :USR1, :USR2, :CONT, :HUP, :WINCH, ]
CHUNK_SIZE = 
(16 * 1024)
VERSION = 
"0.5.2"

Class Attribute Summary collapse

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Methods included from Logging

app, log, log_worker, procline, reopen_logs!

Constructor Details

#initialize(config) ⇒ Pool

Returns a new instance of Pool.



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# File 'lib/qless/pool.rb', line 24

def initialize(config)
  init_config(config)
  @workers = Hash.new { |workers, queues| workers[queues] = {} }
  procline "(initialized)"
end

Class Attribute Details

.app_name ⇒ Object

Returns the value of attribute app_name.



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# File 'lib/qless/pool.rb', line 68

def app_name
  @app_name
end

.config_files ⇒ Object

Returns the value of attribute config_files.



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# File 'lib/qless/pool.rb', line 68

def config_files
  @config_files
end

.term_behavior ⇒ Object

Returns the value of attribute term_behavior.



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

def term_behavior
  @term_behavior
end

Instance Attribute Details

#config ⇒ Object (readonly)

Returns the value of attribute config.



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# File 'lib/qless/pool.rb', line 21

def config
  @config
end

#workers ⇒ Object (readonly)

Returns the value of attribute workers.



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# File 'lib/qless/pool.rb', line 22

def workers
  @workers
end

Class Method Details

.after_prefork(&block) ⇒ Object

The ‘after_prefork` hook will be run in workers if you are using the preforking master worker to save memory. Use this hook to reload database connections and so forth to ensure that they’re not shared among workers.

Call with a block to set the hook. Call with no arguments to return the hook.



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# File 'lib/qless/pool.rb', line 51

def self.after_prefork(&block)
  block ? (@after_prefork = block) : @after_prefork
end

.after_prefork=(after_prefork) ⇒ Object

Set the after_prefork proc.



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# File 'lib/qless/pool.rb', line 56

def self.after_prefork=(after_prefork)
  @after_prefork = after_prefork
end

.choose_config_file ⇒ Object 



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# File 'lib/qless/pool.rb', line 81

def self.choose_config_file
  if ENV["QLESS_POOL_CONFIG"]
    ENV["QLESS_POOL_CONFIG"]
  else
    @config_files.detect { |f| File.exist?(f) }
  end
end

.handle_winch=(bool) ⇒ Object 



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# File 'lib/qless/pool.rb', line 77

def self.handle_winch=(bool)
  @handle_winch = bool
end

.handle_winch? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/qless/pool.rb', line 74

def self.handle_winch?
  @handle_winch ||= false
end

.pool_factory ⇒ Object 



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# File 'lib/qless/pool.rb', line 30

def self.pool_factory
  @pool_factory ||= Qless::PoolFactory.new
end

.pool_factory=(factory) ⇒ Object 



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# File 'lib/qless/pool.rb', line 38

def self.pool_factory=(factory)
  @pool_factory = factory
end

.run ⇒ Object 



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# File 'lib/qless/pool.rb', line 89

def self.run
  if GC.respond_to?(:copy_on_write_friendly=)
    GC.copy_on_write_friendly = true
  end
  Qless::Pool.new(choose_config_file).start.join
end

Instance Method Details

#all_known_queues ⇒ Object 



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# File 'lib/qless/pool.rb', line 340

def all_known_queues
  config.keys | workers.keys
end

#all_pids ⇒ Object 



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# File 'lib/qless/pool.rb', line 319

def all_pids
  workers.map {|q,workers| workers.keys }.flatten
end

#awaken_master ⇒ Object 



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# File 'lib/qless/pool.rb', line 151

def awaken_master
  begin
    self_pipe.last.write_nonblock('.') # wakeup master process from select
  rescue Errno::EAGAIN, Errno::EINTR
    # pipe is full, master should wake up anyways
    retry
  end
end

#call_after_prefork! ⇒ Object 



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# File 'lib/qless/pool.rb', line 60

def call_after_prefork!
  self.class.after_prefork && self.class.after_prefork.call
end

#config_file ⇒ Object

}}} Config: load config and config file {{{



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# File 'lib/qless/pool.rb', line 99

def config_file
  @config_file || (!@config && ::Qless::Pool.choose_config_file)
end

#configured_worker_count ⇒ Object 



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# File 'lib/qless/pool.rb', line 373

def configured_worker_count
  config.values.inject {|sum,x| sum + x }
end

#create_worker(queues) ⇒ Object 



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# File 'lib/qless/pool.rb', line 408

def create_worker(queues)
  pool_factory.worker(queues)
end

#delete_worker(pid) ⇒ Object

TODO: close any file descriptors connected to worker, if any



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# File 'lib/qless/pool.rb', line 311

def delete_worker(pid)
  worker = nil
  workers.detect do |queues, pid_to_worker|
    worker = pid_to_worker.delete(pid)
  end
  worker
end

#environment ⇒ Object 



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# File 'lib/qless/pool.rb', line 123

def environment
  if defined?(Rails) && Rails.respond_to?(:env)
    Rails.env
  elsif defined? RAILS_ENV
    RAILS_ENV
  else
    ENV['RACK_ENV'] || ENV['RAILS_ENV'] || ENV['QLESS_ENV']
  end
end

#graceful_worker_shutdown!(signal) ⇒ Object 



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# File 'lib/qless/pool.rb', line 227

def graceful_worker_shutdown!(signal)
  log "#{signal}: immediate shutdown (graceful worker shutdown)"
  signal_all_workers(:QUIT)
  :break
end

#graceful_worker_shutdown_and_wait!(signal) ⇒ Object 



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# File 'lib/qless/pool.rb', line 220

def graceful_worker_shutdown_and_wait!(signal)
  log "#{signal}: graceful shutdown, waiting for children"
  signal_all_workers(:QUIT)
  reap_all_workers(0) # will hang until all workers are shutdown
  :break
end

#handle_sig_queue! ⇒ Object 



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# File 'lib/qless/pool.rb', line 181

def handle_sig_queue!
  case signal = sig_queue.shift
  when :USR1, :USR2, :CONT
    log "#{signal}: sending to all workers"
    signal_all_workers(signal)
  when :HUP
    log "HUP: reload config file and reload logfiles"
    load_config
    Logging.reopen_logs!
    log "HUP: gracefully shutdown old children (which have old logfiles open)"
    signal_all_workers(:QUIT)
    log "HUP: new children will inherit new logfiles"
    maintain_worker_count
  when :WINCH
    if self.class.handle_winch?
      log "WINCH: gracefully stopping all workers"
      @config = {}
      maintain_worker_count
    end
  when :QUIT
    graceful_worker_shutdown_and_wait!(signal)
  when :INT
    graceful_worker_shutdown!(signal)
  when :TERM
    case self.class.term_behavior
    when "graceful_worker_shutdown_and_wait"
      graceful_worker_shutdown_and_wait!(signal)
    when "graceful_worker_shutdown"
      graceful_worker_shutdown!(signal)
    else
      shutdown_everything_now!(signal)
    end
  end
end

#init_config(config) ⇒ Object 



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# File 'lib/qless/pool.rb', line 103

def init_config(config)
  case config
  when String, nil
    @config_file = config
  else
    @config = config.dup
  end
  load_config
end

#init_self_pipe! ⇒ Object 



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# File 'lib/qless/pool.rb', line 140

def init_self_pipe!
  self_pipe.each { |io| io.close rescue nil }
  self_pipe.replace(IO.pipe)
  self_pipe.each { |io| io.fcntl(Fcntl::F_SETFD, Fcntl::FD_CLOEXEC) }
end

#init_sig_handlers! ⇒ Object 



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

def init_sig_handlers!
  QUEUE_SIGS.each { |sig| trap_deferred(sig) }
  trap(:CHLD)     { |_| awaken_master }
end

#join ⇒ Object 



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# File 'lib/qless/pool.rb', line 261

def join
  loop do
    reap_all_workers
    break if handle_sig_queue! == :break
    if sig_queue.empty?
      master_sleep
      maintain_worker_count
    end
    procline("managing #{all_pids.inspect}")
  end
  procline("(shutting down)")
  #stop # gracefully shutdown all workers on our way out
  log "manager finished"
  #unlink_pid_safe(pid) if pid
end

#load_config ⇒ Object 



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

def load_config
  if config_file
    @config = YAML.load(ERB.new(IO.read(config_file)).result)
  else
    @config ||= {}
  end
  environment and @config[environment] and config.merge!(@config[environment])
  config.delete_if {|key, value| value.is_a? Hash }
end

#maintain_worker_count ⇒ Object

}}} ???: maintain_worker_count, all_known_queues {{{



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# File 'lib/qless/pool.rb', line 332

def maintain_worker_count
  all_known_queues.each do |queues|
    delta = worker_delta_for(queues)
    spawn_missing_workers_for(queues, delta) if delta > 0
    quit_excess_workers_for(queues, delta.abs)   if delta < 0
  end
end

#master_sleep ⇒ Object 



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# File 'lib/qless/pool.rb', line 277

def master_sleep
  begin
    ready = IO.select([self_pipe.first], nil, nil, 1) or return
    ready.first && ready.first.first or return
    loop { self_pipe.first.read_nonblock(CHUNK_SIZE) }
  rescue Errno::EAGAIN, Errno::EINTR
  end
end

#pids_for(queues) ⇒ Object 



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# File 'lib/qless/pool.rb', line 383

def pids_for(queues)
  workers[queues].keys
end

#pool_factory ⇒ Object 



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# File 'lib/qless/pool.rb', line 34

def pool_factory
  self.class.pool_factory
end

#quit_excess_workers_for(queues, delta) ⇒ Object 



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# File 'lib/qless/pool.rb', line 352

def quit_excess_workers_for(queues, delta)
  pids_for(queues)[0...delta].each do |pid|
    Process.kill("QUIT", pid)
  end
end

#reap_all_workers(waitpid_flags = Process::WNOHANG) ⇒ Object

}}} worker process management {{{



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# File 'lib/qless/pool.rb', line 289

def reap_all_workers(waitpid_flags=Process::WNOHANG)
  @waiting_for_reaper = waitpid_flags == 0
  begin
    loop do
      # -1, wait for any child process
      wpid, status = Process.waitpid2(-1, waitpid_flags)
      break unless wpid

      if worker = delete_worker(wpid)
        log "Reaped qless worker[#{status.pid}] (status: #{status.exitstatus}) queues: #{worker.job_reserver.queues.collect(&:name).join(",")}"
      else
        # this died before it could be killed, so it's not going to have any extra info
        log "Tried to reap worker [#{status.pid}], but it had already died. (status: #{status.exitstatus})"
      end
    end
  rescue Errno::EINTR
    retry
  rescue Errno::ECHILD, QuitNowException
  end
end

#report_worker_pool_pids ⇒ Object 



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# File 'lib/qless/pool.rb', line 253

def report_worker_pool_pids
  if workers.empty?
    log "Pool is empty"
  else
    log "Pool contains worker PIDs: #{all_pids.inspect}"
  end
end

#reset_sig_handlers! ⇒ Object 



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# File 'lib/qless/pool.rb', line 177

def reset_sig_handlers!
  QUEUE_SIGS.each {|sig| trap(sig, "DEFAULT") }
end

#running_worker_count ⇒ Object

use qless to get a number for currently running workers on a machine so we don’t double up after a restart with long running jobs still active



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# File 'lib/qless/pool.rb', line 361

def running_worker_count
  # may want to do a zcard on ql:workers instead
  count = 0
  machine_hostname = Socket.gethostname
  worker_info = pool_factory.client.workers.counts
  worker_info.each do |worker|
    hostname, pid = worker['name'].split('-')
    count += 1 if machine_hostname == hostname
  end
  count
end

#self_pipe ⇒ Object

Sig handlers and self pipe management {{{



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# File 'lib/qless/pool.rb', line 137

def self_pipe; @self_pipe ||= [] end

#shutdown_everything_now!(signal) ⇒ Object 



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# File 'lib/qless/pool.rb', line 233

def shutdown_everything_now!(signal)
  log "#{signal}: immediate shutdown (and immediate worker shutdown)"
  signal_all_workers(:TERM)
  :break
end

#sig_queue ⇒ Object 



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# File 'lib/qless/pool.rb', line 138

def sig_queue; @sig_queue ||= [] end

#signal_all_workers(signal) ⇒ Object 



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

def signal_all_workers(signal)
  all_pids.each do |pid|
    Process.kill signal, pid
  end
end

#spawn_missing_workers_for(queues, delta) ⇒ Object

}}} methods that operate on a single grouping of queues {{{ perhaps this means a class is waiting to be extracted



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# File 'lib/qless/pool.rb', line 348

def spawn_missing_workers_for(queues, delta)
  delta.times { spawn_worker!(queues) }
end

#spawn_worker!(queues) ⇒ Object 



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# File 'lib/qless/pool.rb', line 387

def spawn_worker!(queues)
  worker = create_worker(queues)
  pid = fork do
    # This var gets cached, so need to clear it out in forks
    # so that workers report the correct name to qless
    Qless.instance_variable_set(:@worker_name, nil)
    pool_factory.client.redis.client.reconnect
    log_worker "Starting worker #{worker}"
    call_after_prefork!
    reset_sig_handlers!
    #self_pipe.each {|io| io.close }
    begin
      worker.work((ENV['INTERVAL'] || DEFAULT_WORKER_INTERVAL).to_i) # interval, will block
    rescue Errno::EINTR
      log "Caught interrupted system call Errno::EINTR. Retrying."
      retry
    end
  end
  workers[queues][pid] = worker
end

#start ⇒ Object

}}} start, join, and master sleep {{{



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# File 'lib/qless/pool.rb', line 242

def start
  procline("(starting)")
  init_self_pipe!
  init_sig_handlers!
  maintain_worker_count
  procline("(started)")
  log "started manager"
  report_worker_pool_pids
  self
end

#trap_deferred(signal) ⇒ Object

defer a signal for later processing in #join (master process)



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

def trap_deferred(signal)
  trap(signal) do |sig_nr|
    if @waiting_for_reaper && [:INT, :TERM].include?(signal)
      log "Recieved #{signal}: short circuiting QUIT waitpid"
      raise QuitNowException
    end
    if sig_queue.size < SIG_QUEUE_MAX_SIZE
      sig_queue << signal
      awaken_master
    else
      log "ignoring SIG#{signal}, queue=#{sig_queue.inspect}"
    end
  end
end

#worker_delta_for(queues) ⇒ Object 



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# File 'lib/qless/pool.rb', line 377

def worker_delta_for(queues)
  delta = config.fetch(queues, 0) - workers.fetch(queues, []).size
  delta = 0 if delta > 0 && running_worker_count > configured_worker_count
  delta
end