Improve handling of SIGCONT after SIGTERM

lib/fluent/supervisor.rb

@@ -190,6 +190,12 @@ def install_supervisor_signal_handlers
         $log.debug 'fluentd supervisor process got SIGUSR2'
         supervisor_sigusr2_handler
       end
+
+      term_handler = trap :TERM do
+        # After SIGTERM, disable the sigdump file by ignoring SIGCONT.
+        trap(:CONT, nil)
+        term_handler.call
+      end
     end
 
     if Fluent.windows?
@@ -922,6 +928,9 @@ def install_main_process_signal_handlers
       end
 
       trap :TERM do
+        # After SIGTERM, disable the sigdump file by ignoring SIGCONT.
+        trap(:CONT, nil)
+
         $log.debug "fluentd main process get SIGTERM"
         unless @finished
           @finished = true

test/test_supervisor.rb

@@ -32,6 +32,7 @@ def setup
     @tmp_dir = tmp_dir
     @tmp_root_dir = File.join(@tmp_dir, 'root')
     FileUtils.mkdir_p(@tmp_dir)
+    @sigdump_path = "/tmp/sigdump-#{$$}.log"
   end
 
   def teardown
@@ -191,7 +192,7 @@ def test_system_config
     end
   end
 
-  def test_main_process_signal_handlers
+  def test_usr1_in_main_process_signal_handlers
     omit "Windows cannot handle signals" if Fluent.windows?
 
     create_info_dummy_logger
@@ -213,6 +214,52 @@ def test_main_process_signal_handlers
     $log.out.reset if $log && $log.out && $log.out.respond_to?(:reset)
   end
 
+  def test_cont_in_main_processsignal_handlers
+    omit "Windows cannot handle signals" if Fluent.windows?
+
+    opts = Fluent::Supervisor.default_options
+    sv = Fluent::Supervisor.new(opts)
+    sv.send(:install_main_process_signal_handlers)
+
+    begin
+      Process.kill :CONT, $$
+    rescue
+    end
+
+    sleep 1
+
+    assert_true File.exist?(@sigdump_path)
+  ensure
+    File.delete(@sigdump_path) if File.exist?(@sigdump_path)
+  end
+
+  def test_term_cont_in_main_processsignal_handlers
+    omit "Windows cannot handle signals" if Fluent.windows?
+
+    create_debug_dummy_logger
+
+    opts = Fluent::Supervisor.default_options
+    sv = Fluent::Supervisor.new(opts)
+    sv.send(:install_main_process_signal_handlers)
+
+    begin
+      Process.kill :TERM, $$
+      Process.kill :CONT, $$
+    rescue
+    end
+
+    sleep 1
+
+    debug_msg = '[debug]: fluentd main process get SIGTERM' + "\n"
+    logs = $log.out.logs
+    assert{ logs.any?{|log| log.include?(debug_msg) } }
+
+    assert_false File.exist?(@sigdump_path)
+  ensure
+    $log.out.reset if $log && $log.out && $log.out.respond_to?(:reset)
+    File.delete(@sigdump_path) if File.exist?(@sigdump_path)
+  end
+
   def test_main_process_command_handlers
     omit "Only for Windows, alternative to UNIX signals" unless Fluent.windows?
 
@@ -239,7 +286,7 @@ def test_main_process_command_handlers
     $log.out.reset if $log && $log.out && $log.out.respond_to?(:reset)
   end
 
-  def test_supervisor_signal_handler
+  def test_usr1_in_supervisor_signal_handler
     omit "Windows cannot handle signals" if Fluent.windows?
 
     create_debug_dummy_logger
@@ -260,6 +307,43 @@ def test_supervisor_signal_handler
     $log.out.reset if $log && $log.out && $log.out.respond_to?(:reset)
   end
 
+  def test_cont_in_supervisor_signal_handler
+    omit "Windows cannot handle signals" if Fluent.windows?
+
+    server = DummyServer.new
+    server.install_supervisor_signal_handlers
+    begin
+      Process.kill :CONT, $$
+    rescue
+    end
+
+    sleep 1
+
+    assert_true File.exist?(@sigdump_path)
+  ensure
+    File.delete(@sigdump_path) if File.exist?(@sigdump_path)
+  end
+
+  # TODO Sending SIGTERM terminates the test itself.
+  # I think we have to figure out a good way.
+  # def test_term_cont_in_supervisor_signal_handler
+  #   omit "Windows cannot handle signals" if Fluent.windows?
+  #
+  #   server = DummyServer.new
+  #   server.install_supervisor_signal_handlers
+  #   begin
+  #     Process.kill :TERM, $$
+  #     Process.kill :CONT, $$
+  #   rescue
+  #   end
+  #
+  #   sleep 1
+  #
+  #   assert_not File.exist?(@sigdump_path)
+  # ensure
+  #   File.delete(@sigdump_path) if File.exist?(@sigdump_path)
+  # end
+
   def test_windows_shutdown_event
     omit "Only for Windows platform" unless Fluent.windows?