Tolerate connection close failures in #restart

lib/action_cable/server/base.rb

@@ -73,6 +73,8 @@ def disconnect(identifiers)
       def restart
         connections.each do |connection|
           connection.close(reason: ActionCable::INTERNAL[:disconnect_reasons][:server_restart])
+        rescue => e
+          logger&.error "Failed to close connection during restart: [#{e.class} - #{e.message}]: #{e.backtrace.first(5).join(" | ")}"
         end
 
         @mutex.synchronize do

test/server/base_test.rb

@@ -15,6 +15,12 @@ def close
     end
   end
 
+  class RaisingConnection
+    def close(*)
+      raise ClosedQueueError, "queue closed"
+    end
+  end
+
   test "#restart closes all open connections" do
     conn = FakeConnection.new
     @server.add_connection(conn)
@@ -35,4 +41,64 @@ def close
       @server.restart
     end
   end
+
+  test "#restart does not propagate exceptions raised by connection#close" do
+    @server.add_connection(RaisingConnection.new)
+
+    assert_nothing_raised do
+      @server.restart
+    end
+  end
+
+  test "#restart still closes remaining connections when one #close raises" do
+    @server.add_connection(RaisingConnection.new)
+    survivor = FakeConnection.new
+    @server.add_connection(survivor)
+
+    assert_called(survivor, :close) do
+      @server.restart
+    end
+  end
+
+  test "#restart still shuts down worker pool when connection#close raises" do
+    @server.add_connection(RaisingConnection.new)
+
+    assert_called(@server.worker_pool, :halt) do
+      @server.restart
+    end
+  end
+
+  test "#restart still shuts down pub/sub when connection#close raises" do
+    @server.add_connection(RaisingConnection.new)
+
+    assert_called(@server.pubsub, :shutdown) do
+      @server.restart
+    end
+  end
+
+  test "#restart is safe to call twice when a connection#close raises" do
+    @server.add_connection(RaisingConnection.new)
+
+    @server.restart
+    assert_nothing_raised do
+      @server.restart
+    end
+  end
+
+  test "#restart logs an error including the exception class when connection#close raises" do
+    @server.add_connection(RaisingConnection.new)
+
+    log = StringIO.new
+    old_logger = @server.config.logger
+    @server.config.logger = Logger.new(log)
+
+    begin
+      @server.restart
+
+      log.rewind
+      assert_match(/ClosedQueueError.*queue closed/, log.read)
+    ensure
+      @server.config.logger = old_logger
+    end
+  end
 end