Fixes Cluster worker shutdown/restart (#1908)

* cluster.rb - fixup worker wait in Cluster, add Worker#term?

1. Cluster - fix wait in #check_workers, #stop_workers
2. Cluster - add private wait_workers method for use in above
2. Worker  - add #term? method for use in above

* Adds two tests for worker SIGTERM/respawn and phased-restart

test_worker_spawn_external_term - sends SIGTERM to workers, checks respawn, etc

test_worker_phased_restart - checking worker handling during phased-restart

lib/puma/cluster.rb

@@ -74,6 +74,10 @@ module Puma
         @started_at = Time.now
         @last_checkin = Time.now
         @last_status = '{}'
+<<<<<<< HEAD
+=======
+        @dead = false
+>>>>>>> Fixes Cluster worker shutdown/restart (#1908)
         @term = false
       end
 
@@ -92,6 +96,10 @@ module Puma
         @term
       end
 
+      def term?
+        @term
+      end
+
       def ping!(status)
         @last_checkin = Time.now
         @last_status = status

test/test_integration.rb

@@ -9,8 +9,12 @@ require "open3"
 # TODO: remove stdout logging, get everything out of my rainbow dots
 
 class TestIntegration < Minitest::Test
+<<<<<<< HEAD
   HOST  = "127.0.0.1"
   TOKEN = "xxyyzz"
+=======
+  HOST = '127.0.0.1'
+>>>>>>> Fixes Cluster worker shutdown/restart (#1908)
 
   def setup
     @state_path   = "test/test_#{name}_puma.state"
@@ -533,4 +537,129 @@ class TestIntegration < Minitest::Test
 
     [thr, launcher, @events]
   end
+
+  def test_worker_spawn_external_term
+    worker_respawn { |l, old_pids|
+      old_pids.each { |p| Process.kill :TERM, p }
+    }
+  end
+
+  def test_worker_phased_restart
+    worker_respawn { |l, old_pids| l.phased_restart }
+  end
+
+  private
+
+  def worker_respawn
+    skip NO_FORK_MSG unless HAS_FORK
+    port = UniquePort.call
+    workers_booted = 0
+
+    conf = Puma::Configuration.new do |c|
+      c.bind "tcp://#{HOST}:#{port}"
+      c.threads 1, 1
+      c.workers 2
+      c.worker_shutdown_timeout 2
+      c.app TestApps::SLEEP
+      c.after_worker_fork { |idx| workers_booted += 1 }
+    end
+
+    # start Puma via launcher
+    thr, launcher, _e = run_launcher conf
+
+    # make sure two workers have booted
+    time = 0
+    until workers_booted >= 2 || time >= 10
+      sleep 2
+      time += 2
+    end
+
+    cluster = launcher.instance_variable_get :@runner
+
+    http0 = Net::HTTP.new HOST, port
+    http1 = Net::HTTP.new HOST, port
+    body0 = nil
+    body1 = nil
+
+    worker0 = Thread.new do
+      begin
+        req0 = Net::HTTP::Get.new "/sleep35", {}
+        http0.start.request(req0) { |rep0| body0 = rep0.body }
+      rescue
+      end
+    end
+
+    worker1 = Thread.new do
+      begin
+        req1 = Net::HTTP::Get.new "/sleep40", {}
+        http1.start.request(req1) { |rep1| body1 = rep1.body }
+      rescue
+      end
+    end
+
+    old_pids = cluster.instance_variable_get(:@workers).map(&:pid)
+
+    start_time = Time.now.to_f
+
+    # below should 'cancel' the phase 0 workers, either via phased_restart or
+    # externally SIGTERM'ing them
+    yield launcher, old_pids
+
+    # make sure four workers have booted
+    time = 0
+    until workers_booted >= 4 || time >= 45
+      sleep 2
+      time += 2
+    end
+
+    new_pids = cluster.instance_variable_get(:@workers).map(&:pid)
+
+    # should be empty if all old workers removed
+    old_waited = old_pids.map { |pid|
+      begin
+        Process.wait(pid, Process::WNOHANG)
+        pid
+      rescue Errno::ECHILD
+        nil # child is already terminated
+      end
+    }.compact
+
+    Thread.kill worker0
+    Thread.kill worker1
+
+    launcher.stop
+    assert_kind_of Thread, thr.join, "server didn't stop"
+
+    refute_equal 'Slept 35', body0
+    refute_equal 'Slept 40', body1
+
+    # Since 35 is the shorter of the two requests, server should restart
+    # and cancel both requests
+    assert_operator (Time.now.to_f - start_time).round(2), :<, 35
+
+    msg = "old_pids #{old_pids.inspect}  new_pids #{new_pids.inspect}  old_waited #{old_waited.inspect}"
+    assert_equal 2, new_pids.length, msg
+    assert_equal 2, old_pids.length, msg
+    assert_empty new_pids & old_pids, "#{msg}\nBoth workers should be replaced with new"
+    assert_empty old_waited, msg
+  end
+
+  def run_launcher(conf)
+    # below for future PR
+    #@wait, @ready = IO.pipe
+    # @ios_to_close << @wait << @ready
+    #@events = Puma::Events.strings
+    #@events.on_booted { @ready << "!" }
+
+    launcher = Puma::Launcher.new conf, :events => @events
+
+    thr = Thread.new do
+      launcher.run
+    end
+
+    # wait for boot from #@events.on_booted
+    @wait.sysread 1
+
+    [thr, launcher, @events]
+   end
 end