[DB-SIG] MySQL lost connections
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
>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
>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
>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.
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