summaryrefslogtreecommitdiff
path: root/sidekiq_cluster/sidekiq_cluster.rb
blob: 49478ba740ddfd9597f3d1ad5a8241ea06d5b736 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
# frozen_string_literal: true

require_relative 'dependencies'

module Gitlab
  module SidekiqCluster
    CHECK_TERMINATE_INTERVAL_SECONDS = 1

    # How long to wait when asking for a clean termination.
    # It maps the Sidekiq default timeout:
    # https://github.com/mperham/sidekiq/wiki/Signals#term
    #
    # This value is passed to Sidekiq's `-t` if none
    # is given through arguments.
    DEFAULT_SOFT_TIMEOUT_SECONDS = 25

    # After surpassing the soft timeout.
    DEFAULT_HARD_TIMEOUT_SECONDS = 5

    # The signals that should terminate both the master and workers.
    TERMINATE_SIGNALS = %i(INT TERM).freeze

    # The signals that should simply be forwarded to the workers.
    FORWARD_SIGNALS = %i(TTIN USR1 USR2 HUP).freeze

    # Traps the given signals and yields the block whenever these signals are
    # received.
    #
    # The block is passed the name of the signal.
    #
    # Example:
    #
    #     trap_signals(%i(HUP TERM)) do |signal|
    #       ...
    #     end
    def self.trap_signals(signals)
      signals.each do |signal|
        trap(signal) do
          yield signal
        end
      end
    end

    def self.trap_terminate(&block)
      trap_signals(TERMINATE_SIGNALS, &block)
    end

    def self.trap_forward(&block)
      trap_signals(FORWARD_SIGNALS, &block)
    end

    def self.signal(pid, signal)
      Process.kill(signal, pid)
      true
    rescue Errno::ESRCH
      false
    end

    def self.signal_processes(pids, signal)
      pids.each { |pid| signal(pid, signal) }
    end

    # Starts Sidekiq workers for the pairs of processes.
    #
    # Example:
    #
    #     start([ ['foo'], ['bar', 'baz'] ], :production)
    #
    # This would start two Sidekiq processes: one processing "foo", and one
    # processing "bar" and "baz". Each one is placed in its own process group.
    #
    # queues - An Array containing Arrays. Each sub Array should specify the
    #          queues to use for a single process.
    #
    # directory - The directory of the Rails application.
    #
    # Returns an Array containing the PIDs of the started processes.
    def self.start(queues, env: :development, directory: Dir.pwd, max_concurrency: 50, min_concurrency: 0, timeout: DEFAULT_SOFT_TIMEOUT_SECONDS, dryrun: false)
      queues.map.with_index do |pair, index|
        start_sidekiq(pair, env: env,
                            directory: directory,
                            max_concurrency: max_concurrency,
                            min_concurrency: min_concurrency,
                            worker_id: index,
                            timeout: timeout,
                            dryrun: dryrun)
      end
    end

    # Starts a Sidekiq process that processes _only_ the given queues.
    #
    # Returns the PID of the started process.
    def self.start_sidekiq(queues, env:, directory:, max_concurrency:, min_concurrency:, worker_id:, timeout:, dryrun:)
      counts = count_by_queue(queues)

      cmd = %w[bundle exec sidekiq]
      cmd << "-c#{self.concurrency(queues, min_concurrency, max_concurrency)}"
      cmd << "-e#{env}"
      cmd << "-t#{timeout}"
      cmd << "-gqueues:#{proc_details(counts)}"
      cmd << "-r#{directory}"

      counts.each do |queue, count|
        cmd << "-q#{queue},#{count}"
      end

      if dryrun
        puts Shellwords.join(cmd) # rubocop:disable Rails/Output
        return
      end

      pid = Process.spawn(
        { 'ENABLE_SIDEKIQ_CLUSTER' => '1',
          'SIDEKIQ_WORKER_ID' => worker_id.to_s },
        *cmd,
        pgroup: true,
        err: $stderr,
        out: $stdout
      )

      wait_async(pid)

      pid
    end

    def self.count_by_queue(queues)
      queues.tally
    end

    def self.proc_details(counts)
      counts.map do |queue, count|
        if count == 1
          queue
        else
          "#{queue} (#{count})"
        end
      end.join(',')
    end

    def self.concurrency(queues, min_concurrency, max_concurrency)
      concurrency_from_queues = queues.length + 1
      max = max_concurrency > 0 ? max_concurrency : concurrency_from_queues
      min = [min_concurrency, max].min

      concurrency_from_queues.clamp(min, max)
    end

    # Waits for the given process to complete using a separate thread.
    def self.wait_async(pid)
      Thread.new do
        Process.wait(pid) rescue Errno::ECHILD
      end
    end

    # Returns true if all the processes are alive.
    def self.all_alive?(pids)
      pids.each do |pid|
        return false unless process_alive?(pid)
      end

      true
    end

    def self.any_alive?(pids)
      pids_alive(pids).any?
    end

    def self.pids_alive(pids)
      pids.select { |pid| process_alive?(pid) }
    end

    def self.process_alive?(pid)
      # Signal 0 tests whether the process exists and we have access to send signals
      # but is otherwise a noop (doesn't actually send a signal to the process)
      signal(pid, 0)
    end

    def self.write_pid(path)
      File.open(path, 'w') do |handle|
        handle.write(Process.pid.to_s)
      end
    end
  end
end