Class: Gitlab::Cluster::LifecycleEvents

Inherits:
Object
  • Object
show all
Defined in:
lib/gitlab/cluster/lifecycle_events.rb

Overview

LifecycleEvents lets Rails initializers register application startup hooks that are sensitive to forking. For example, to defer the creation of watchdog threads. This lets us abstract away the Unix process lifecycles of Sidekiq, Puma, Puma Cluster, etc.

We have the following lifecycle events.

  • on_before_fork (on master process):

    Puma Cluster: This will be called exactly once,
  on startup, before the workers are forked. This is
  called in the PARENT/MASTER process.

Sidekiq/Puma Single: This is not called.

  • on_master_start (on master process):

    Puma Cluster: This will be called exactly once,
  on startup, before the workers are forked. This is
  called in the PARENT/MASTER process.

Sidekiq/Puma Single: This is called immediately.

  • on_before_blackout_period (on master process):

    Puma Cluster: This will be called before a blackout
  period when performing graceful shutdown of master.
  This is called on `master` process.

Sidekiq/Puma Single: This is not called.

  • on_before_graceful_shutdown (on master process):

    Puma Cluster: This will be called before a graceful
  shutdown  of workers starts happening, but after blackout period.
  This is called on `master` process.

Sidekiq/Puma Single: This is not called.

  • on_before_master_restart (on master process):

    Puma Cluster: This will be called before a new master is spun up.
  This is called on `master` process.

Sidekiq/Puma Single: This is not called.

  • on_worker_start (on worker process):

    Puma Cluster: This is called in the worker process
  exactly once before processing requests.

Sidekiq/Puma Single: This is called immediately.

  • on_worker_stop (on worker process):

    Puma Cluster: Called in the worker process
  exactly once after it stops processing requests
  but before it shuts down.

Sidekiq: Called after the scheduler shuts down but
  before the worker finishes ongoing jobs.

Blocks will be executed in the order in which they are registered.

Constant Summary collapse

FatalError =

rubocop:disable Lint/InheritException

Class.new(Exception)
USE_FATAL_LIFECYCLE_EVENTS = 
Gitlab::Utils.to_boolean(ENV.fetch('GITLAB_FATAL_LIFECYCLE_EVENTS', 'true'))

Class Method Summary collapse

Class Method Details

.do_before_fork ⇒ Object 



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# File 'lib/gitlab/cluster/lifecycle_events.rb', line 136

def do_before_fork
  call(:before_fork_hooks, @before_fork_hooks)
end

.do_before_graceful_shutdown ⇒ Object 



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# File 'lib/gitlab/cluster/lifecycle_events.rb', line 140

def do_before_graceful_shutdown
  call(:master_blackout_period, @master_blackout_period)

  blackout_seconds = ::Settings.shutdown.blackout_seconds.to_i
  sleep(blackout_seconds) if blackout_seconds > 0

  call(:master_graceful_shutdown, @master_graceful_shutdown)
end

.do_before_master_restart ⇒ Object Also known as: do_master_restart 



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# File 'lib/gitlab/cluster/lifecycle_events.rb', line 149

def do_before_master_restart
  call(:master_restart_hooks, @master_restart_hooks)
end

.do_worker_start ⇒ Object

Lifecycle integration methods (called from puma.rb, etc.)



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# File 'lib/gitlab/cluster/lifecycle_events.rb', line 132

def do_worker_start
  call(:worker_start_hooks, @worker_start_hooks)
end

.do_worker_stop ⇒ Object 



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# File 'lib/gitlab/cluster/lifecycle_events.rb', line 153

def do_worker_stop
  call(:worker_stop_hooks, @worker_stop_hooks)
end

.on_before_blackout_period(&block) ⇒ Object

Read the config/initializers/cluster_events_before_phased_restart.rb



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# File 'lib/gitlab/cluster/lifecycle_events.rb', line 101

def on_before_blackout_period(&block)
  # Defer block execution
  (@master_blackout_period ||= []) << block
end

.on_before_fork(&block) ⇒ Object 



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# File 'lib/gitlab/cluster/lifecycle_events.rb', line 95

def on_before_fork(&block)
  # Defer block execution
  (@before_fork_hooks ||= []) << block
end

.on_before_graceful_shutdown(&block) ⇒ Object

Read the config/initializers/cluster_events_before_phased_restart.rb



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# File 'lib/gitlab/cluster/lifecycle_events.rb', line 107

def on_before_graceful_shutdown(&block)
  # Defer block execution
  (@master_graceful_shutdown ||= []) << block
end

.on_before_master_restart(&block) ⇒ Object 



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# File 'lib/gitlab/cluster/lifecycle_events.rb', line 112

def on_before_master_restart(&block)
  # Defer block execution
  (@master_restart_hooks ||= []) << block
end

.on_master_start(&block) ⇒ Object 



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# File 'lib/gitlab/cluster/lifecycle_events.rb', line 117

def on_master_start(&block)
  if in_clustered_puma?
    on_before_fork(&block)
  else
    on_worker_start(&block)
  end
end

.on_worker_start(&block) ⇒ Object

Hook registration methods (called from initializers)



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# File 'lib/gitlab/cluster/lifecycle_events.rb', line 86

def on_worker_start(&block)
  if in_clustered_puma?
    # Defer block execution
    (@worker_start_hooks ||= []) << block
  else
    yield
  end
end

.on_worker_stop(&block) ⇒ Object 



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# File 'lib/gitlab/cluster/lifecycle_events.rb', line 125

def on_worker_stop(&block)
  (@worker_stop_hooks ||= []) << block
end

.set_puma_options(options) ⇒ Object

Puma doesn’t use singletons (which is good) but this means we need to pass through whether the puma server is running in single mode or cluster mode



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# File 'lib/gitlab/cluster/lifecycle_events.rb', line 163

def set_puma_options(options)
  @puma_options = options
end