Redirect sidekiq output to sidekiq-cluster

This redirects STDERR and STDOUT of the various Sidekiq processes to the
sidekiq-cluster process. The logging output of sidekiq-cluster itself
has been changed so it matches Sidekiq's output more closely, making
parsing/grepping easier.

Fixes #1438

bin/sidekiq-cluster

 #!/usr/bin/env ruby
 
 require 'optparse'
-require 'thread'
 require_relative '../lib/gitlab/sidekiq_cluster'
 require_relative '../lib/gitlab/sidekiq_cluster/cli'
 

lib/gitlab/sidekiq_cluster.rb

-require 'open3'
-
 module Gitlab
   module SidekiqCluster
     # The signals that should terminate both the master and workers.
@@ -41,15 +39,15 @@ module Gitlab
       false
     end
 
-    def self.signal_threads(threads, signal)
-      threads.each { |thread| signal(thread.pid, signal) }
+    def self.signal_processes(pids, signal)
+      pids.each { |pid| signal(pid, signal) }
     end
 
     def self.parse_queues(array)
       array.map { |chunk| chunk.split(',') }
     end
 
-    # Starts Sidekiq workers for the pairs of threads.
+    # Starts Sidekiq workers for the pairs of processes.
     #
     # Example:
     #
@@ -61,29 +59,47 @@ module Gitlab
     # queues - An Array containing Arrays. Each sub Array should specify the
     #          queues to use for a single process.
     #
-    # Returns an Array containing the threads monitoring each process.
+    # Returns an Array containing the PIDs of the started processes.
     def self.start(queues, env)
       queues.map { |pair| start_sidekiq(pair, env) }
     end
 
     # Starts a Sidekiq process that processes _only_ the given queues.
+    #
+    # Returns the PID of the started process.
     def self.start_sidekiq(queues, env)
       switches = queues.map { |q| "-q #{q},1" }
 
-      Open3.popen3({ 'ENABLE_SIDEKIQ_CLUSTER' => '1' },
-                   'bundle',
-                   'exec',
-                   'sidekiq',
-                   "-c #{queues.length + 1}",
-                   "-e#{env}",
-                   "-gqueues: #{queues.join(', ')}",
-                   *switches).last
+      pid = Process.spawn(
+        { 'ENABLE_SIDEKIQ_CLUSTER' => '1' },
+        'bundle',
+        'exec',
+        'sidekiq',
+        "-c #{queues.length + 1}",
+        "-e#{env}",
+        "-gqueues: #{queues.join(', ')}",
+        "-r#{directory}",
+        *switches,
+        err: $stderr,
+        out: $stdout
+      )
+
+      wait_async(pid)
+
+      pid
+    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/threads are alive.
-    def self.all_alive?(threads)
-      threads.each do |thread|
-        return false unless signal(thread.pid, 0)
+    # Returns true if all the processes are alive.
+    def self.all_alive?(pids)
+      pids.each do |pid|
+        return false unless signal(pid, 0)
       end
 
       true

lib/gitlab/sidekiq_cluster/cli.rb

 require 'optparse'
 require 'logger'
+require 'time'
 
 module Gitlab
   module SidekiqCluster
@@ -11,8 +12,13 @@ module Gitlab
         @pid = nil
         @interval = 5
         @alive = true
-        @threads = []
+        @processes = []
         @logger = Logger.new(log_output)
+
+        # Use a log format similar to Sidekiq to make parsing/grepping easier.
+        @logger.formatter = proc do |level, date, program, message|
+          "#{date.utc.iso8601(3)} #{Process.pid} TID-#{Thread.current.object_id.to_s(36)} #{level}: #{message}\n"
+        end
       end
 
       def run(argv = ARGV)
@@ -27,7 +33,7 @@ module Gitlab
 
         @logger.info("Starting cluster with #{queues.length} processes")
 
-        @threads = SidekiqCluster.start(queues, @environment)
+        @processes = SidekiqCluster.start(queues, @environment)
 
         write_pid
         trap_signals
@@ -41,11 +47,11 @@ module Gitlab
       def trap_signals
         SidekiqCluster.trap_terminate do |signal|
           @alive = false
-          SidekiqCluster.signal_threads(@threads, signal)
+          SidekiqCluster.signal_processes(@processes, signal)
         end
 
         SidekiqCluster.trap_forward do |signal|
-          SidekiqCluster.signal_threads(@threads, signal)
+          SidekiqCluster.signal_processes(@processes, signal)
         end
       end
 
@@ -53,12 +59,12 @@ module Gitlab
         while @alive
           sleep(@interval)
 
-          unless SidekiqCluster.all_alive?(@threads)
+          unless SidekiqCluster.all_alive?(@processes)
             # If a child process died we'll just terminate the whole cluster. It's up to
             # runit and such to then restart the cluster.
             @logger.info('A worker terminated, shutting down the cluster')
 
-            SidekiqCluster.signal_threads(@threads, :TERM)
+            SidekiqCluster.signal_processes(@processes, :TERM)
             break
           end
         end

spec/lib/gitlab/sidekiq_cluster/cli_spec.rb

@@ -51,13 +51,13 @@ describe Gitlab::SidekiqCluster::CLI do
   end
 
   describe '#start_loop' do
-    it 'runs until one of the threads has been terminated' do
+    it 'runs until one of the processes has been terminated' do
       allow(cli).to receive(:sleep).with(a_kind_of(Numeric))
 
       expect(Gitlab::SidekiqCluster).to receive(:all_alive?).
         with(an_instance_of(Array)).and_return(false)
 
-      expect(Gitlab::SidekiqCluster).to receive(:signal_threads).
+      expect(Gitlab::SidekiqCluster).to receive(:signal_processes).
         with(an_instance_of(Array), :TERM)
 
       cli.start_loop

spec/lib/gitlab/sidekiq_cluster_spec.rb

@@ -40,13 +40,11 @@ describe Gitlab::SidekiqCluster do
     end
   end
 
-  describe '.signal_threads' do
+  describe '.signal_processes' do
     it 'sends a signal to every thread' do
-      thread = double(:thread, pid: 1)
+      expect(described_class).to receive(:signal).with(1, :INT)
 
-      expect(described_class).to receive(:signal).with(thread.pid, :INT)
-
-      described_class.signal_threads([thread], :INT)
+      described_class.signal_processes([1], :INT)
     end
   end
 
@@ -71,30 +69,37 @@ describe Gitlab::SidekiqCluster do
 
   describe '.start_sidekiq' do
     it 'starts a Sidekiq process' do
-      thread = double(:thread, pid: 1)
+      allow(Process).to receive(:spawn).and_return(1)
+
+      expect(described_class).to receive(:wait_async).with(1)
+      expect(described_class.start_sidekiq(%w(foo), :production)).to eq(1)
+    end
+  end
 
-      allow(Open3).to receive(:popen3).
-        and_return([double(:stdout), double(:stderr), double(:stdin), thread])
+  describe '.wait_async' do
+    it 'waits for a process in a separate thread' do
+      thread = described_class.wait_async(Process.spawn('true'))
 
-      expect(described_class.start_sidekiq(%w(foo), :production)).to eq(thread)
+      # Upon success Process.wait just returns the PID.
+      expect(thread.value).to be_a_kind_of(Numeric)
     end
   end
 
   describe '.all_alive?' do
-    it 'returns true if all threads are alive' do
-      threads = [double(:thread, pid: 1)]
+    it 'returns true if all processes are alive' do
+      processes = [1]
 
       allow(described_class).to receive(:signal).with(1, 0).and_return(true)
 
-      expect(described_class.all_alive?(threads)).to eq(true)
+      expect(described_class.all_alive?(processes)).to eq(true)
     end
 
     it 'returns false when a thread was not alive' do
-      threads = [double(:thread, pid: 1)]
+      processes = [1]
 
       allow(described_class).to receive(:signal).with(1, 0).and_return(false)
 
-      expect(described_class.all_alive?(threads)).to eq(false)
+      expect(described_class.all_alive?(processes)).to eq(false)
     end
   end