diff --git a/README.txt b/README.txt
index 061eee0..e71c56f 100644
--- a/README.txt
+++ b/README.txt
@@ -284,3 +284,31 @@ in the callback options.
     httprl_send_request();
     ?>
 
+
+Pass by reference example. Example is D7 only; pass by reference works in
+D6 & D7.
+
+    <?php
+    // Code from system_rebuild_module_data().
+    $modules = _system_rebuild_module_data();
+    ksort($modules);
+
+    // Show first module before running system_get_files_database().
+    echo httprl_pr(current($modules));
+
+    $callback_options = array(
+      array(
+        'function' => 'system_get_files_database',
+        'return' => '',
+      ),
+      &$modules, 'module'
+    );
+    httprl_queue_background_callback($callback_options);
+
+    // Execute requests.
+    httprl_send_request();
+
+    // Show first module after running system_get_files_database().
+    echo httprl_pr(current($modules));
+    ?>
+
diff --git a/httprl.async.inc b/httprl.async.inc
index bcf3493..423a6a7 100644
--- a/httprl.async.inc
+++ b/httprl.async.inc
@@ -23,14 +23,14 @@ function httprl_async_page() {
   }
 
   // Exit if the temp_key does not match a lock that has been taken.
-  // Wait up to 5 seconds for the lock to propagate out.
+  // Wait up to 2.5 seconds for the lock to propagate out.
   $tries = 0;
   while (lock_may_be_available($_POST['temp_key'])) {
     $tries++;
     if ($tries > 5) {
       httprl_fast403();
     }
-    sleep(1);
+    usleep(500000); // Sleep for 500 miliseconds;
   }
 
   // If request was a non blocking one, cut the connection right here.
@@ -47,7 +47,13 @@ function httprl_async_page() {
   }
 
   // Unpack arguments.
-  $args = unserialize($_POST['args']);
+  $input_args = unserialize($_POST['args']);
+
+  // Pass by reference trick for call_user_func_array().
+  $args = array();
+  foreach ($input_args as &$arg) {
+    $args[] = &$arg;
+  }
 
   // Caputure anything printed out.
   ob_start();
diff --git a/httprl.module b/httprl.module
index b962eff..6b7fd2d 100644
--- a/httprl.module
+++ b/httprl.module
@@ -1261,6 +1261,7 @@ function httprl_decode_data(&$result) {
     }
     $result->data = $output;
   }
+  // Decompress if compressed.
   elseif (isset($result->headers['content-encoding'])) {
     if ($result->headers['content-encoding'] == 'gzip') {
       $result->data = gzinflate(substr($result->data, 10));
@@ -1477,17 +1478,24 @@ function httprl_lock_release($name) {
  *   Human readable HTML version of the data.
  */
 function httprl_pr($data) {
+  // Get extra arguments passed in.
   $data = func_get_args();
   if (count($data) == 1) {
     $data = array_pop($data);
   }
+
+  // Remove non UTF-8 Characters, escape HTML markup, remove extra new lines.
   $output = array_filter(explode("\n", htmlentities(iconv('utf-8', 'utf-8//IGNORE', print_r($data, TRUE)), ENT_QUOTES, 'UTF-8')));
+
+  // Whitespace compression.
   foreach ($output as $key => $value) {
     if (str_replace('    ', '', $value) == "(") {
       $output[$key-1] .= ' (';
       unset($output[$key]);
     }
   }
-  $output = str_replace('    ', '&nbsp;&nbsp;&nbsp;&nbsp;', nl2br(implode("\n", $output)));
+
+  // Replace whitespace with html markup.
+  $output = str_replace('    ', '&nbsp;&nbsp;&nbsp;&nbsp;', nl2br(implode("\n", $output))) . '<br />';
   return $output;
 }