Better names for thread pool threads (#2657)

lib/puma/server.rb

@@ -227,6 +227,7 @@ def run(background=true, thread_name: 'server')
       @status = :run
 
       @thread_pool = ThreadPool.new(
+        thread_name,
         @min_threads,
         @max_threads,
         ::Puma::IOBuffer,

lib/puma/thread_pool.rb

@@ -29,7 +29,7 @@ class ForceShutdown < RuntimeError
     # The block passed is the work that will be performed in each
     # thread.
     #
-    def initialize(min, max, *extra, &block)
+    def initialize(name, min, max, *extra, &block)
       @not_empty = ConditionVariable.new
       @not_full = ConditionVariable.new
       @mutex = Mutex.new
@@ -39,6 +39,7 @@ def initialize(min, max, *extra, &block)
       @spawned = 0
       @waiting = 0
 
+      @name = name
       @min = Integer(min)
       @max = Integer(max)
       @block = block
@@ -101,7 +102,7 @@ def spawn_thread
       @spawned += 1
 
       th = Thread.new(@spawned) do |spawned|
-        Puma.set_thread_name 'threadpool %03i' % spawned
+        Puma.set_thread_name '%s threadpool %03i' % [@name, spawned]
         todo  = @todo
         block = @block
         mutex = @mutex
@@ -319,12 +320,12 @@ def stop
     end
 
     def auto_trim!(timeout=30)
-      @auto_trim = Automaton.new(self, timeout, "threadpool trimmer", :trim)
+      @auto_trim = Automaton.new(self, timeout, "#{@name} threadpool trimmer", :trim)
       @auto_trim.start!
     end
 
     def auto_reap!(timeout=5)
-      @reaper = Automaton.new(self, timeout, "threadpool reaper", :reap)
+      @reaper = Automaton.new(self, timeout, "#{@name} threadpool reaper", :reap)
       @reaper.start!
     end
 

test/test_thread_pool.rb

@@ -10,12 +10,12 @@ def teardown
 
   def new_pool(min, max, &block)
     block = proc { } unless block
-    @pool = Puma::ThreadPool.new(min, max, &block)
+    @pool = Puma::ThreadPool.new('test', min, max, &block)
   end
 
   def mutex_pool(min, max, &block)
     block = proc { } unless block
-    @pool = MutexPool.new(min, max, &block)
+    @pool = MutexPool.new('test', min, max, &block)
   end
 
   # Wraps ThreadPool work in mutex for better concurrency control.
@@ -59,7 +59,7 @@ def test_thread_name
     thread_name = nil
     pool = mutex_pool(0, 1) {thread_name = Thread.current.name}
     pool << 1
-    assert_equal('puma threadpool 001', thread_name)
+    assert_equal('puma test threadpool 001', thread_name)
   end
 
   def test_converts_pool_sizes