Index: branches/RC/core/install/install_schema.sql
===================================================================
diff -u -N -r11870 -r11933
--- branches/RC/core/install/install_schema.sql	(.../install_schema.sql)	(revision 11870)
+++ branches/RC/core/install/install_schema.sql	(.../install_schema.sql)	(revision 11933)
@@ -1088,4 +1088,15 @@
   Title VARCHAR(255) NOT NULL DEFAULT '',
   Description text,
   PRIMARY KEY  (FormId)
+);
+
+CREATE TABLE Semaphores (
+  SemaphoreId int(11) NOT NULL auto_increment,
+  SessionKey int(10) unsigned NOT NULL,
+  Timestamp int(10) unsigned NOT NULL,
+  MainPrefix varchar(255) NOT NULL,
+  PRIMARY KEY  (SemaphoreId),
+  KEY SessionKey (SessionKey),
+  KEY Timestamp (Timestamp),
+  KEY MainPrefix (MainPrefix)
 );
\ No newline at end of file
Index: branches/RC/core/install/remove_schema.sql
===================================================================
diff -u -N -r11623 -r11933
--- branches/RC/core/install/remove_schema.sql	(.../remove_schema.sql)	(revision 11623)
+++ branches/RC/core/install/remove_schema.sql	(.../remove_schema.sql)	(revision 11933)
@@ -67,4 +67,5 @@
 DROP TABLE PageContent;
 DROP TABLE FormFields;
 DROP TABLE FormSubmissions;
-DROP TABLE Forms;
\ No newline at end of file
+DROP TABLE Forms;
+DROP TABLE Semaphores;
Index: branches/RC/core/install/upgrades.sql
===================================================================
diff -u -N -r11931 -r11933
--- branches/RC/core/install/upgrades.sql	(.../upgrades.sql)	(revision 11931)
+++ branches/RC/core/install/upgrades.sql	(.../upgrades.sql)	(revision 11933)
@@ -1319,6 +1319,17 @@
 INSERT INTO ConfigurationAdmin VALUES ('DebugOnlyFormConfigurator', 'la_section_SettingsAdmin', 'la_config_DebugOnlyFormConfigurator', 'checkbox', '', '', 40.09, 0, 0);
 INSERT INTO ConfigurationValues VALUES (DEFAULT, 'DebugOnlyFormConfigurator', '0', 'In-Portal', 'in-portal:configure_advanced');
 
+CREATE TABLE Semaphores (
+  SemaphoreId int(11) NOT NULL auto_increment,
+  SessionKey int(10) unsigned NOT NULL,
+  Timestamp int(10) unsigned NOT NULL,
+  MainPrefix varchar(255) NOT NULL,
+  PRIMARY KEY  (SemaphoreId),
+  KEY SessionKey (SessionKey),
+  KEY Timestamp (Timestamp),
+  KEY MainPrefix (MainPrefix)
+);
+
 ALTER TABLE Language ADD IconDisabledURL VARCHAR(255) NULL DEFAULT NULL AFTER IconURL;
 
 UPDATE Phrase
Index: branches/RC/core/kernel/db/db_event_handler.php
===================================================================
diff -u -N -r11930 -r11933
--- branches/RC/core/kernel/db/db_event_handler.php	(.../db_event_handler.php)	(revision 11930)
+++ branches/RC/core/kernel/db/db_event_handler.php	(.../db_event_handler.php)	(revision 11933)
@@ -1,6 +1,6 @@
 <?php
 /**
-* @version	$Id: db_event_handler.php 11930 2009-07-19 13:09:25Z alex $
+* @version	$Id: db_event_handler.php 11933 2009-07-19 13:18:46Z alex $
 * @package	In-Portal
 * @copyright	Copyright (C) 1997 - 2009 Intechnic. All rights reserved.
 * @license      GNU/GPL
@@ -1350,6 +1350,11 @@
 
 				if (!$this->Application->CheckPermission('SYSTEM_ACCESS.READONLY', 1)) {
 					$live_ids = $temp->SaveEdit($event->getEventParam('master_ids') ? $event->getEventParam('master_ids') : Array());
+					if ($live_ids === false) {
+						// coping from table failed, because we have another coping process to same table, that wasn't finished
+						$event->status = erFAIL;
+						return ;
+					}
 
 					// Deleteing files scheduled for delete
 					$var_name = $event->getPrefixSpecial().'_file_pending_actions'.$this->Application->GetVar('m_wid');
Index: branches/RC/core/kernel/utility/temp_handler.php
===================================================================
diff -u -N -r11923 -r11933
--- branches/RC/core/kernel/utility/temp_handler.php	(.../temp_handler.php)	(revision 11923)
+++ branches/RC/core/kernel/utility/temp_handler.php	(.../temp_handler.php)	(revision 11933)
@@ -1,6 +1,6 @@
 <?php
 /**
-* @version	$Id: temp_handler.php 11923 2009-07-19 11:57:31Z alex $
+* @version	$Id: temp_handler.php 11933 2009-07-19 13:18:46Z alex $
 * @package	In-Portal
 * @copyright	Copyright (C) 1997 - 2009 Intechnic. All rights reserved.
 * @license      GNU/GPL
@@ -650,6 +650,24 @@
 		return $this->savedIDs[ $master['Prefix'] ];
 	}
 	
+	/**
+	 * Create separate connection for locking purposes
+	 *
+	 * @return kDBConnection
+	 */
+	function &_getSeparateConnection()
+	{
+		static $connection = null;
+
+		if (!isset($connection)) {
+			$connection = new kDBConnection(SQL_TYPE, Array(&$this->Application, 'handleSQLError') );
+			$connection->debugMode = $this->Application->isDebugMode();
+			$connection->Connect(SQL_SERVER, SQL_USER, SQL_PASS, SQL_DB, true);
+		}
+
+		return $connection;
+	}
+
 	function UpdateChangeLogForeignKeys($master, $live_id, $temp_id)
 	{
 		$main_prefix = $this->Application->GetTopmostPrefix($master['Prefix']);
@@ -766,7 +784,60 @@
 
 	function SaveEdit($master_ids = Array())
 	{
-		return $this->DoCopyTempToOriginal($this->Tables, null, $master_ids);
+		// SessionKey field is required for deleting records from expired sessions
+		$conn =& $this->_getSeparateConnection();
+
+		$sleep_count = 0;
+		do {
+			// aquire lock
+			$conn->ChangeQuery('LOCK TABLES '.TABLE_PREFIX.'Semaphores WRITE');
+
+			$sql = 'SELECT SessionKey
+					FROM ' . TABLE_PREFIX . 'Semaphores
+					WHERE (MainPrefix = ' . $conn->qstr($this->Tables['Prefix']) . ')';
+			$another_coping_active = $conn->GetOne($sql);
+
+			if ($another_coping_active) {
+				// another user is coping data from temp table to live -> release lock and try again after 1 second
+				$conn->ChangeQuery('UNLOCK TABLES');
+				$sleep_count++;
+				sleep(1);
+			}
+		} while ($another_coping_active && ($sleep_count <= 30));
+
+		if ($sleep_count > 30) {
+			// another coping process failed to finished in 30 seconds
+			$error_message = $this->Application->Phrase('la_error_TemporaryTableCopingFailed');
+			$this->Application->SetVar('_temp_table_message', $error_message);
+
+			return false;
+		}
+
+		// mark, that we are coping from temp to live right now, so other similar attempt (from another script) will fail
+		$fields_hash = Array (
+			'SessionKey' => $this->Application->GetSID(),
+			'Timestamp' => adodb_mktime(),
+			'MainPrefix' => $this->Tables['Prefix'],
+		);
+
+		$conn->doInsert($fields_hash, TABLE_PREFIX.'Semaphores');
+		$semaphore_id = $conn->getInsertID();
+
+		// unlock table now to prevent permanent lock in case, when coping will end with SQL error in the middle
+		$conn->ChangeQuery('UNLOCK TABLES');
+
+		$ids = $this->DoCopyTempToOriginal($this->Tables, null, $master_ids);
+
+		// remove mark, that we are coping from temp to live
+		$conn->Query('LOCK TABLES '.TABLE_PREFIX.'Semaphores WRITE');
+
+		$sql = 'DELETE FROM ' . TABLE_PREFIX . 'Semaphores
+				WHERE SemaphoreId = ' . $semaphore_id;
+		$conn->ChangeQuery($sql);
+
+		$conn->ChangeQuery('UNLOCK TABLES');
+
+		return $ids;
 	}
 
 	function CancelEdit($master=null)
Index: branches/RC/core/admin_templates/incs/footer.tpl
===================================================================
diff -u -N -r11661 -r11933
--- branches/RC/core/admin_templates/incs/footer.tpl	(.../footer.tpl)	(revision 11661)
+++ branches/RC/core/admin_templates/incs/footer.tpl	(.../footer.tpl)	(revision 11933)
@@ -38,6 +38,14 @@
 
 		InitEditors();
 	</inp2:m_if>
+
+	<inp2:m_if check="m_Get" name="_temp_table_message">
+		addLoadEvent(
+			function() {
+				alert('<inp2:m_Get name="_temp_table_message" js_escape="1"/>');
+			}
+		);
+	</inp2:m_if>
 </script>
 
 <inp2:m_ifnot check="adm_UsePopups">