Revert "Merge pull request ManageIQ#16130 from jrafanie/fork_workers_…

…no_more"

Reverting for now since worker_options for spawn were not properly being
passed to the run_single_worker script, specifically the ems_id.

This reverts commit f885db2, reversing
changes made to b7a986d.

Gemfile

@@ -41,6 +41,7 @@ gem "manageiq-api-client",            "~>0.1.0",       :require => false
 gem "manageiq-network_discovery",     "~>0.1.2",       :require => false
 gem "mime-types",                     "~>2.6.1",       :path => "mime-types-redirector"
 gem "more_core_extensions",           "~>3.3"
+gem "nakayoshi_fork",                 "~>0.0.3"  # provides a more CoW friendly fork (GC a few times before fork)
 gem "net-ldap",                       "~>0.14.0",      :require => false
 gem "net-ping",                       "~>1.7.4",       :require => false
 gem "net-ssh",                        "=3.2.0",        :require => false

app/models/miq_worker.rb

@@ -304,6 +304,29 @@ def send_message_to_worker_monitor(message, *args)
     )
   end
 
+  def self.before_fork
+    preload_for_worker_role if respond_to?(:preload_for_worker_role)
+  end
+
+  def self.after_fork
+    close_pg_sockets_inherited_from_parent
+    DRb.stop_service
+    renice(Process.pid)
+  end
+
+  # When we fork, the children inherits the parent's file descriptors
+  # so we need to close any inherited raw pg sockets in the child.
+  def self.close_pg_sockets_inherited_from_parent
+    owner_to_pool = ActiveRecord::Base.connection_handler.instance_variable_get(:@owner_to_pool)
+    owner_to_pool[Process.ppid].values.compact.each do |pool|
+      pool.connections.each do |conn|
+        socket = conn.raw_connection.socket
+        _log.info("Closing socket: #{socket}")
+        IO.for_fd(socket).close
+      end
+    end
+  end
+
   # Overriding queue_name as now some queue names can be
   # arrays of names for some workers not just a singular name.
   # We use JSON.parse as the array of names is stored as a string.
@@ -316,6 +339,26 @@ def queue_name
     end
   end
 
+  def start_runner
+    if ENV['MIQ_SPAWN_WORKERS'] || !Process.respond_to?(:fork)
+      start_runner_via_spawn
+    else
+      start_runner_via_fork
+    end
+  end
+
+  def start_runner_via_fork
+    self.class.before_fork
+    pid = fork(:cow_friendly => true) do
+      self.class.after_fork
+      self.class::Runner.start_worker(worker_options)
+      exit!
+    end
+
+    Process.detach(pid)
+    pid
+  end
+
   def self.build_command_line(guid)
     command_line = "#{Gem.ruby} #{runner_script} --heartbeat --guid=#{guid} #{name}"
     ENV['APPLIANCE'] ? "nice #{nice_increment} #{command_line}" : command_line
@@ -327,7 +370,7 @@ def self.runner_script
     script
   end
 
-  def start_runner
+  def start_runner_via_spawn
     pid = Kernel.spawn(self.class.build_command_line(guid), [:out, :err] => [Rails.root.join("log", "evm.log"), "a"])
     Process.detach(pid)
     pid

lib/workers/bin/run_single_worker.rb

@@ -55,7 +55,7 @@
 require File.expand_path("../../../config/environment", __dir__)
 
 worker_class = worker_class.constantize
-worker_class.preload_for_worker_role if worker_class.respond_to?(:preload_for_worker_role)
+worker_class.before_fork
 unless options[:dry_run]
   create_options = {:pid => Process.pid}
   runner_options = {}