Remove old visitors in single process

src/mibew/libs/track.php

@@ -21,6 +21,7 @@
 use Mibew\EventDispatcher\EventDispatcher;
 use Mibew\EventDispatcher\Events;
 use Mibew\Database;
+use Mibew\ProcessLock;
 use Mibew\Settings;
 use Mibew\Thread;
 
@@ -196,6 +197,8 @@ function track_retrieve_details($visitor)
  */
 function track_remove_old_visitors()
 {
+    $lock = new ProcessLock('visitors_remove_old');
+    if ($lock->get()) {
         $db = Database::getInstance();
 
         // Remove associations of visitors with closed threads
@@ -218,6 +221,10 @@ function track_remove_old_visitors()
                 ':now' => time(),
             )
         );
+
+        // Release the lock
+        $lock->release();
+    }
 }
 
 /**