Revert "Fix child processes not being reaped when Process.detach us…

…ed (puma#3314)"

This reverts commit 9bd838b.

Did this start to happen after this commit? Sure looks like that so far
https://github.com/dentarg/puma/actions/runs/7709969145/job/21012318760#step:10:43

lib/puma/cluster.rb

@@ -563,12 +563,9 @@ def wait_workers
       @workers.reject! do |w|
         next false if w.pid.nil?
         begin
-          # We may need to check the PID individually because:
-          # 1. From Ruby versions 2.6 to 3.2, `Process.detach` can prevent or delay
-          #    `Process.wait2(-1)` from detecting a terminated process: https://bugs.ruby-lang.org/issues/19837.
-          # 2. When `fork_worker` is enabled, some worker may not be direct children,
-          #    but grand children.  Because of this they won't be reaped by `Process.wait2(-1)`.
-          if reaped_children.delete(w.pid) || Process.wait(w.pid, Process::WNOHANG)
+          # When `fork_worker` is enabled, some worker may not be direct children, but grand children.
+          # Because of this they won't be reaped by `Process.wait2(-1)`, so we need to check them individually)
+          if reaped_children.delete(w.pid) || (@options[:fork_worker] && Process.wait(w.pid, Process::WNOHANG))
             true
           else
             w.term if w.term?

test/test_integration_cluster.rb

@@ -175,34 +175,6 @@ def test_stuck_external_term_spawn
     end
   end
 
-  # From Ruby 2.6 to 3.2, `Process.detach` can delay or prevent
-  # `Process.wait2(-1)` from detecting a terminated child:
-  # https://bugs.ruby-lang.org/issues/19837. However,
-  # `Process.wait2(<child pid>)` still works properly. This bug has
-  # been fixed in Ruby 3.3.
-  def test_workers_respawn_with_process_detach
-    skip_unless_signal_exist? :KILL
-
-    config = 'test/config/process_detach_before_fork.rb'
-
-    worker_respawn(0, workers, config) do |phase0_worker_pids|
-      phase0_worker_pids.each do |pid|
-        Process.kill :KILL, pid
-      end
-    end
-
-    # `test/config/process_detach_before_fork.rb` forks and detaches a
-    # process.  Since MiniTest attempts to join all threads before
-    # finishing, terminate the process so that the test can end quickly
-    # if it passes.
-    pid_filename = File.join(Dir.tmpdir, 'process_detach_test.pid')
-    if File.exist?(pid_filename)
-      pid = File.read(pid_filename).chomp.to_i
-      File.unlink(pid_filename)
-      Process.kill :TERM, pid if pid > 0
-    end
-  end
-
   # mimicking stuck workers, test restart
   def test_stuck_phased_restart
     skip_unless_signal_exist? :USR1
@@ -709,10 +681,10 @@ def usr1_all_respond(unix: false, config: '')
     end
   end
 
-  def worker_respawn(phase = 1, size = workers, config = 'test/config/worker_shutdown_timeout_2.rb')
+  def worker_respawn(phase = 1, size = workers)
     threads = []
 
-    cli_server "-w #{workers} -t 1:1 -C #{config} test/rackup/sleep_pid.ru"
+    cli_server "-w #{workers} -t 1:1 -C test/config/worker_shutdown_timeout_2.rb test/rackup/sleep_pid.ru"
 
     # make sure two workers have booted
     phase0_worker_pids = get_worker_pids