Improve benchmarking instructions and dangling memory references

examples/99-server-benchmark-download.php

@@ -1,11 +1,18 @@
 <?php
 
+// A simple HTTP web server that can be used to benchmark requests per second and download speed
+//
 // $ php examples/99-server-benchmark-download.php 8080
+//
+// This example runs the web server on a single CPU core in order to measure the
+// per core performance.
+//
 // $ curl http://localhost:8080/10g.bin > /dev/null
 // $ wget http://localhost:8080/10g.bin -O /dev/null
-// $ ab -n10 -c10 http://localhost:8080/1g.bin
-// $ docker run -it --rm --net=host jordi/ab -n100000 -c10 http://localhost:8080/
-// $ docker run -it --rm --net=host jordi/ab -n10 -c10 http://localhost:8080/1g.bin
+// $ ab -n10 -c10 -k http://localhost:8080/1g.bin
+// $ docker run -it --rm --net=host jordi/ab -n100000 -c10 -k http://localhost:8080/
+// $ docker run -it --rm --net=host jordi/ab -n10 -c10 -k http://localhost:8080/1g.bin
+// $ docker run -it --rm --net=host skandyla/wrk -t8 -c10 -d20 http://localhost:8080/
 
 use Evenement\EventEmitter;
 use Psr\Http\Message\ServerRequestInterface;

src/Io/RequestHeaderParser.php

@@ -106,10 +106,6 @@ public function handle(ConnectionInterface $conn)
                 $stream->close();
             }
         });
-
-        $conn->on('close', function () use (&$buffer, &$fn) {
-            $fn = $buffer = null;
-        });
     }
 
     /**

src/Io/StreamingServer.php

@@ -367,7 +367,8 @@ public function handleResponse(ConnectionInterface $connection, ServerRequestInt
         if ($persist) {
             $body->pipe($connection, array('end' => false));
             $parser = $this->parser;
-            $body->on('end', function () use ($connection, $parser) {
+            $body->on('end', function () use ($connection, $parser, $body) {
+                $connection->removeListener('close', array($body, 'close'));
                 $parser->handle($connection);
             });
         } else {

tests/Io/StreamingServerTest.php

@@ -3001,7 +3001,9 @@ public function testNewConnectionWillInvokeParserTwiceAfterInvokingRequestHandle
         // pretend parser just finished parsing
         $server->handleRequest($this->connection, $request);
 
+        $this->assertCount(2, $this->connection->listeners('close'));
         $body->end();
+        $this->assertCount(1, $this->connection->listeners('close'));
     }
 
     private function createGetRequest()