[DB-SIG] MySQL lost connections

Paul DuBois paul at snake.net
Fri Mar 5 11:17:06 EST 2004

At 10:10 -0500 3/5/04, Lloyd Kvam wrote:
>I have been getting python program failures involving lost connections to a
>MySQL database.  The server is a Redhat (9) Linux box.  The clients 
>are running
>Win2K.  To research the issue, I've been running tcpdump on the 
>server to trace
>the packet flow.  The following text describes what I found from tcpdump.  My
>guess is that this is really some kind of Windows problem, but I have not had
>any success getting information on that front.  I'd appreciate any thoughts or
>suggestions.  Thanks.
>At 11:54:01 we have the PC acknowledging successful receipt of the 
>previous packet from
>the database.  I assume the PC operator heads off to lunch at this 
>point, leaving
>the program running.
>Then at 12:59:02 the PC tries to open a new connection from port 
>3648 rather than 1497,
>the port it had been using.  The database accepts the new connection.
>At 12:59:03 the PC resets (closes) the new connection.  I believe 
>that this is when the
>program realized it had lost its working connection and aborted.
>At 12:59:09 a new connection from port 3650 is establised.  I 
>believe this is from the
>program being restarted.  3650 was still working when I wrote this email.
>So, what's going on???
>My guess is that Windows is terminating the idle connection even 
>though the program is
>still running!!!  When the program tries to use the connection that 
>it had never closed,
>Windows attempts to open a new connection.  However, that never 
>connection never established
>the login with the database, so it doesn't work.  The program now 
>aborts because it has
>lost its working database connection.  Once the program is 
>restarted, we are back to normal.
>I will try to research whether this idea can possibly be correct.

Check the version of MySQL on the Windows side.  There was a problem
in 4.0.15 that caused Windows clients to time out very quickly.


Note 6th item in "bugs fixed" section.

More information about the DB-SIG mailing list