ID: 20298 Comment by: phpbugs at kevin dot offwhite dot net Reported By: phpbug at tab1 dot clara dot co dot uk Status: Verified Bug Type: ODBC related Operating System: * PHP Version: 4CVS, 5CVS (2004-04-13) New Comment:
Well, after some additional research I have turned up what I think is the exact cause of the bug, but I don't feel qualified to implement the solution. In the php code, at line 2271 in php_odbc.c ( http://lxr.php.net/source/php-src/ext/odbc/php_odbc.c#2271 ), php calls SQLGetInfo() passing a parameter of SQL_DATA_SOURCE_READ_ONLY to try and determine if the connection is alive or not. While this may work in some odbc drivers, it is not the "official" way of asking if the connection is dead. According to my driver supplier ( http://www-912.ibm.com/o_dir/odbcforum.nsf/8178b1c14b1e9b6b8525624f0062fe9f/B0CFDBA3D8DBAC0F86256EA80077D2B9?OpenDocument ) and the Microsoft's ODBC Programmer's reference ( http://msdn.microsoft.com/library/default.asp?url=/library/en-us/odbc/htm/odbcodbc_connection_pooling.asp ), the correct method is to use SQLGetConnectAttr() to check the Attribute SQL_ATTR_CONNECTION_DEAD. Steps to reproduce: 1) Use PHP's odbc_pconnect() function with the iSeries ODBC Driver for Linux. 2) Allow the connection to idle long enough for the Server to disconnect. 3) Try and use the connection which was disconnected by the server. Expected result: 1) PHP calls SQLGetConnectAttr() to check SQL_ATTR_CONNECTION_DEAD, which returns SQL_ERROR. 2) PHP removes the connection from its internal list, creates a new persistent connection, and returns that new connection to the php script 3) call to odbc_exec() succeeds. Actual result: 1) PHP calls SQLGetInfo() to check SQL_DATA_SOURCE_READ_ONLY, which returns SQL_SUCCESS 2) PHP believes this to be a valid connection, and returns this connection to the php script 3) call to odbc_exec() fails. Previous Comments: ------------------------------------------------------------------------ [2004-04-02 10:48:58] phpbugs at kevin dot offwhite dot net I'm seeing this problem on a Red Hat 9 system running PHP 4.3.5 on Apache 2.0. I have check_persistent and allow_persistent On, and phpinfo() reports 1 active persistent link. I'm not clear if the problem is in the ODBC Driver not reporting back to php that the server has terminated the link, or if PHP is not properly checking if the persistent link needs to be re-established, but I thought it wouldn't hurt to report the bug here and see what we can come up with. An interesting thing is that while phpinfo() reports only one persistent link, a netstat on the webserver shows 6 connections to the database server. When I load the page with the odbc_pconnect call, it will alternate between working and not working from pageload to pageload, so it seems that some of those connections are good and others are not, and php is not removing the bad connection from the hash list. The error message I get is: Warning: odbc_exec(): SQL error: [unixODBC][IBM][iSeries Access ODBC Driver]Communication link failure. comm rc=10054 - CWBCO1047 - The iSeries server application disconnected the connection, SQL state 08S01 in SQLExecDirect in /usr/local/apache/htdocs/test.php on line 15 ------------------------------------------------------------------------ [2003-12-02 04:47:47] phpbug at tab1 dot clara dot co dot uk okay this was tested with: php4-win32-STABLE-200312020930 1st run: resource(2) of type (odbc link persistent) followed by the correct query results 2nd run (after killing db connection): resource(1) of type (odbc link persistent) Warning: odbc_exec(): SQL error: [Informix][Informix ODBC Driver]Communication link failure., SQL state 08S01 in SQLExecDirect in C:\InetPub\wwwroot\test.php on line 8 ------------------------------------------------------------------------ [2003-12-01 03:00:17] [EMAIL PROTECTED] Can you add 'var_dump($dbconn);' after that odbc_pconnect() call..? What does it output? (in the re-run) ------------------------------------------------------------------------ [2003-02-20 04:58:12] t_o_m_ at yahoo dot com Having reread all of this I see that nowhere have I mentioned I'm using IIS (ISAPI) not Apache, if that makes a difference? I thought when I put Windows in the OS box whoever read it would assume IIS. In answer to your question "no", the behaviour is the same if odbc.check_persistent is on or off. The point is when it is off I would expect it to be my responsibility to check the connection and would expect the error if I did not. I would expect that when odbc.check_persistent was on odbc_pconnect was supposed to check the connection for me if the connection it is about to return from its pool is dead then it should discard it and create a new one as when the pool is empty. Which is clearly not happening. ------------------------------------------------------------------------ [2003-02-18 12:01:03] [EMAIL PROTECTED] Well the nature of CGI doesn't really lend itself to supporting persistant connections. It's run when requested and then exited after that. So no data can really presist between pages that exists solely in the CGI. So this behavior only exists when odbc.check_persistent is turned on? ------------------------------------------------------------------------ The remainder of the comments for this report are too long. To view the rest of the comments, please view the bug report online at http://bugs.php.net/20298 -- Edit this bug report at http://bugs.php.net/?id=20298&edit=1
