3 files changed, 16 insertions, 10 deletions
diff --git a/admin/batch_manager_global.php b/admin/batch_manager_global.php
index ce1b2f745..befbf2d48 100644
--- a/admin/batch_manager_global.php
+++ b/admin/batch_manager_global.php
@@ -42,12 +42,6 @@ foreach ($upload_form_config as $param_shortname => $param)
   $form_values[$param_shortname] = $conf[$param_name];
 }
 
-// User cache must not be regenerated during simultaneous ajax requests
-if (!isset($user['need_update']) or !$user['need_update'])
-{
-  getuserdata($user['id'], true);
-}
-
 // +-----------------------------------------------------------------------+
 // | Check Access and exit when user status is not ok                      |
 // +-----------------------------------------------------------------------+
diff --git a/include/dblayer/functions_mysql.inc.php b/include/dblayer/functions_mysql.inc.php
index dbc66d503..785e588e0 100644
--- a/include/dblayer/functions_mysql.inc.php
+++ b/include/dblayer/functions_mysql.inc.php
@@ -416,8 +416,14 @@ UPDATE '.$tablename.'
  * @param array inserts
  * @return void
  */
-function mass_inserts($table_name, $dbfields, $datas)
+function mass_inserts($table_name, $dbfields, $datas, $options=array())
 {
+  $ignore = '';
+  if (isset($options['ignore']) and $options['ignore'])
+  {
+    $ignore = 'IGNORE';
+  }
+  
   if (count($datas) != 0)
   {
     $first = true;
@@ -438,7 +444,7 @@ function mass_inserts($table_name, $dbfields, $datas)
       if ($first)
       {
         $query = '
-INSERT INTO '.$table_name.'
+INSERT '.$ignore.' INTO '.$table_name.'
   ('.implode(',', $dbfields).')
   VALUES';
         $first = false;
diff --git a/include/functions_user.inc.php b/include/functions_user.inc.php
index 63925cfd8..eedd53af5 100644
--- a/include/functions_user.inc.php
+++ b/include/functions_user.inc.php
@@ -446,6 +446,9 @@ DELETE FROM '.USER_CACHE_CATEGORIES_TABLE.'
   WHERE user_id = '.$userdata['id'];
       pwg_query($query);
 
+      // Due to concurrency issues, we ask MySQL to ignore errors on
+      // insert. This may happen when cache needs refresh and that Piwigo is
+      // called "very simultaneously".
       mass_inserts
       (
         USER_CACHE_CATEGORIES_TABLE,
@@ -454,7 +457,8 @@ DELETE FROM '.USER_CACHE_CATEGORIES_TABLE.'
           'user_id', 'cat_id',
           'date_last', 'max_date_last', 'nb_images', 'count_images', 'count_categories'
         ),
-        $user_cache_cats
+        $user_cache_cats,
+        array('ignore' => true)
       );
 
 
@@ -464,8 +468,10 @@ DELETE FROM '.USER_CACHE_TABLE.'
   WHERE user_id = '.$userdata['id'];
       pwg_query($query);
 
+      // for the same reason as user_cache_categories, we ignore error on
+      // this insert
       $query = '
-INSERT INTO '.USER_CACHE_TABLE.'
+INSERT IGNORE INTO '.USER_CACHE_TABLE.'
   (user_id, need_update, cache_update_time, forbidden_categories, nb_total_images,
     image_access_type, image_access_list)
   VALUES