SIGINFO prints thread backtraces

Super basic server test

Add tests for single/cluster

Cleanup

lib/puma/cluster.rb

@@ -273,6 +273,10 @@ def worker(index, master)
         server.stop
       end
 
+      Signal.trap "SIGINFO" do
+        server.log_thread_status
+      end
+
       begin
         @worker_write << "b#{Process.pid}\n"
       rescue SystemCallError, IOError
@@ -346,8 +350,8 @@ def reload_worker_directory
       log "+ Changing to #{dir}"
       Dir.chdir dir
     end
-  
-    # Inside of a child process, this will return all zeroes, as @workers is only populated in 
+
+    # Inside of a child process, this will return all zeroes, as @workers is only populated in
     # the master process.
     def stats
       old_worker_count = @workers.count { |w| w.phase != @phase }

lib/puma/server.rb

@@ -1023,5 +1023,16 @@ def self.current
     def shutting_down?
       @status == :stop || @status == :restart
     end
+
+    def log_thread_status
+      Thread.list.each do |thread|
+        @events.log "Thread TID-#{thread.object_id.to_s(36)} #{thread['label']}"
+        if thread.backtrace
+          @events.log thread.backtrace.join("\n")
+        else
+          @events.log "<no backtrace available>"
+        end
+      end
+    end
   end
 end

lib/puma/single.rb

@@ -113,6 +113,10 @@ def run
 
       @launcher.events.fire_on_booted!
 
+      Signal.trap "SIGINFO" do
+        server.log_thread_status
+      end
+
       begin
         server.run.join
       rescue Interrupt

test/helpers/integration.rb

@@ -97,7 +97,7 @@ def read_body(connection)
   end
 
   # gets worker pids from @server output
-  def get_worker_pids(phase, size = WORKERS)
+  def get_worker_pids(phase = 0, size = WORKERS)
     pids = []
     re = /pid: (\d+)\) booted, phase: #{phase}/
     while pids.size < size

test/test_integration_cluster.rb

@@ -8,6 +8,20 @@ def setup
     super
   end
 
+  def test_siginfo_thread_print
+    skip_unless_signal_exist? :INFO
+
+    cli_server("-w #{WORKERS} -q test/rackup/hello.ru")
+    worker_pids = get_worker_pids
+    output = []
+    t = Thread.new { output << @server.readlines }
+    Process.kill(:INFO, worker_pids.first)
+    Process.kill(:INT, @server.pid)
+    t.join
+
+    assert_match "Thread TID", output.join
+  end
+
   def test_usr2_restart
     _, new_reply = restart_server_and_listen("-q -w #{WORKERS} test/rackup/hello.ru")
     assert_equal "Hello World", new_reply
@@ -92,7 +106,7 @@ def test_term_worker_clean_exit
     pid = cli_server("-w #{WORKERS} test/rackup/hello.ru").pid
 
     # Get the PIDs of the child workers.
-    worker_pids = get_worker_pids 0
+    worker_pids = get_worker_pids
 
     # Signal the workers to terminate, and wait for them to die.
     Process.kill :TERM, pid

test/test_integration_single.rb

@@ -84,4 +84,17 @@ def test_int_signal_with_background_thread_in_jruby
 
     assert_raises(Errno::ECONNREFUSED) { TCPSocket.new(HOST, @tcp_port) }
   end
+
+  def test_siginfo_thread_print
+    skip_unless_signal_exist? :INFO
+
+    cli_server("test/rackup/hello.ru")
+    output = []
+    t = Thread.new { output << @server.readlines }
+    Process.kill(:INFO, @server.pid)
+    Process.kill(:INT, @server.pid)
+    t.join
+
+    assert_match "Thread TID", output.join
+  end
 end

test/test_puma_server.rb

@@ -9,7 +9,7 @@ def setup
 
     @app = lambda { |env| [200, {}, [env['rack.url_scheme']]] }
 
-    @events = Puma::Events.new STDOUT, STDERR
+    @events = Puma::Events.strings
     @server = Puma::Server.new @app, @events
   end
 
@@ -280,9 +280,6 @@ def test_GET_with_no_body_has_sane_chunking
   end
 
   def test_doesnt_print_backtrace_in_production
-    @events = Puma::Events.strings
-    @server = Puma::Server.new @app, @events
-
     @server.app = proc { |e| raise "don't leak me bro" }
     @server.leak_stack_on_error = false
     @server.add_tcp_listener @host, @port
@@ -298,7 +295,6 @@ def test_doesnt_print_backtrace_in_production
   end
 
   def test_prints_custom_error
-    @events = Puma::Events.strings
     re = lambda { |err| [302, {'Content-Type' => 'text', 'Location' => 'foo.html'}, ['302 found']] }
     @server = Puma::Server.new @app, @events, {:lowlevel_error_handler => re}
 
@@ -314,7 +310,6 @@ def test_prints_custom_error
   end
 
   def test_leh_gets_env_as_well
-    @events = Puma::Events.strings
     re = lambda { |err,env|
       env['REQUEST_PATH'] || raise("where is env?")
       [302, {'Content-Type' => 'text', 'Location' => 'foo.html'}, ['302 found']]
@@ -953,4 +948,11 @@ def test_request_body_wait_chunked
 
     assert request_body_wait >= 1000
   end
+
+  def test_siginfo_prints_thread_traces
+    @server.log_thread_status
+    @events.stdout.rewind
+
+    assert_match "Thread TID", @events.stdout.read
+  end
 end