All Puma threads are named

lib/puma.rb

@@ -22,4 +22,10 @@ def self.stats_object=(val)
   def self.stats
     @get_stats.stats
   end
+
+  # Thread name is new in Ruby 2.3
+  def self.set_thread_name(name)
+    return unless Thread.current.respond_to?(:name=)
+    Thread.current.name = "puma #{name}"
+  end
 end

lib/puma/cluster.rb

@@ -248,6 +248,7 @@ def worker(index, master)
       @suicide_pipe.close
 
       Thread.new do
+        Puma.set_thread_name "worker check pipe"
         IO.select [@check_pipe]
         log "! Detected parent died, dying"
         exit! 1
@@ -282,6 +283,7 @@ def worker(index, master)
       end
 
       Thread.new(@worker_write) do |io|
+        Puma.set_thread_name "stat payload"
         base_payload = "p#{Process.pid}"
 
         while true

lib/puma/launcher.rb

@@ -328,6 +328,10 @@ def graceful_stop
     def log_thread_status
       Thread.list.each do |thread|
         @events.log "Thread TID-#{thread.object_id.to_s(36)} #{thread['label']}"
+        logstr = "Thread: TID-#{thread.object_id.to_s(36)}"
+        logstr += " #{thread.name}" if thread.respond_to?(:name)
+        @events.log logstr
+
         if thread.backtrace
           @events.log thread.backtrace.join("\n")
         else

lib/puma/plugin.rb

@@ -63,7 +63,10 @@ def add_background(blk)
 
     def fire_background
       @background.each do |b|
-        Thread.new(&b)
+        Thread.new do
+          set_thread_name "plugin background"
+          b.call
+        end
       end
     end
   end

lib/puma/reactor.rb

@@ -307,6 +307,7 @@ def run
 
     def run_in_thread
       @thread = Thread.new do
+        Puma.set_thread_name "reactor"
         begin
           run_internal
         rescue StandardError => e

lib/puma/server.rb

@@ -207,7 +207,10 @@ def run_lopez_mode(background=true)
       @events.fire :state, :running
 
       if background
-        @thread = Thread.new { handle_servers_lopez_mode }
+        @thread = Thread.new do
+          Puma.set_thread_name "server"
+          handle_servers_lopez_mode
+        end
         return @thread
       else
         handle_servers_lopez_mode
@@ -351,7 +354,10 @@ def run(background=true)
       @events.fire :state, :running
 
       if background
-        @thread = Thread.new { handle_servers }
+        @thread = Thread.new do
+          Puma.set_thread_name "server"
+          handle_servers
+        end
         return @thread
       else
         handle_servers

lib/puma/thread_pool.rb

@@ -87,8 +87,7 @@ def spawn_thread
       @spawned += 1
 
       th = Thread.new(@spawned) do |spawned|
-        # Thread name is new in Ruby 2.3
-        Thread.current.name = 'puma %03i' % spawned if Thread.current.respond_to?(:name=)
+        Puma.set_thread_name 'threadpool %03i' % spawned
         todo  = @todo
         block = @block
         mutex = @mutex
@@ -255,6 +254,7 @@ def start!
         @running = true
 
         @thread = Thread.new do
+          Puma.set_thread_name "threadpool autotrim"
           while @running
             @pool.trim
             sleep @timeout
@@ -284,6 +284,7 @@ def start!
         @running = true
 
         @thread = Thread.new do
+          Puma.set_thread_name "threadpool reaper"
           while @running
             @pool.reap
             sleep @timeout

test/test_integration_cluster.rb

@@ -4,7 +4,7 @@
 class TestIntegrationCluster < TestIntegration
   def setup
     super
-    
+
     skip NO_FORK_MSG unless HAS_FORK
   end
 

test/test_thread_pool.rb

@@ -37,7 +37,7 @@ def test_append_spawns
       @work_done.wait(@work_mutex, 5)
       assert_equal 1, pool.spawned
       assert_equal [1], saw
-      assert_equal('puma 001', thread_name) if Thread.current.respond_to?(:name)
+      assert_equal('puma threadpool 001', thread_name) if Thread.current.respond_to?(:name)
     end
   end