MySQL lost connection errors - related to DB session store?

Rails
1

All,

Win XP
MySQL 5.1.x
Rails 1.1

I recently changed the session store in my app from file to DB (MySQL)
and now I seem to be getting “Lost connection to MySQL server during
query:” errors from MySQL.

I looked at several other posts about the “lost connections” issue, but
then I looked at: http://dev.mysql.com/doc/refman/5.0/en/gone-away.html
and found this:

"You can also get these errors if you send a query to the server that is
incorrect or too large. If mysqld receives a packet that is too large or
out of order, it assumes that something has gone wrong with the client
and closes the connection. If you need big queries (for example, if you
are working with big BLOB columns), you can increase the query limit by
setting the server’s max_allowed_packet variable, which has a default
value of 1MB. You may also need to increase the maximum packet size on
the client end. More information on setting the packet size is given in
Section B.2.9, “Packet too large”. "

Has anyone seen a correlation between using the DB to store session data
and losing connections on MySQL?

Thanks,
Wes

2

Given the above and
http://dev.mysql.com/doc/refman/5.0/en/packet-too-large.html, how would
I set the “max_allowed_packet” on the client side of the MySQL
connection - I assume in the MySQL connection adapter?

Wes

3

I agree with Benoit, you definitely need to install the native mysql
driver. Just do:
gem install mysql

and then pick the driver for win32, it will resolve your problems.

Joe

4

Simply use the native win32 mySQL driver (It is available as a gem).
The ruby one got issues with win32.
The pb is very random. You can have everything working fine for a
while, then suddenly got the connection lost errors.

5

[email protected] wrote:

I agree with Benoit, you definitely need to install the native mysql
driver. Just do:
gem install mysql

and then pick the driver for win32, it will resolve your problems.

Joe

I have been running this app. against MySQL on Win XP for 5 months and
have never seen this problem before.

I’ll install the gem but I’m skeptical.

I don’t have to do anything with the AR connectors?

Thanks,
Wes

6

Based slightly on http://dev.mysql.com/doc/refman/5.0/en/gone-away.html,

you need to:

  1. gem install mysql (I installed 2.7.3 for win32)
  2. Add the directory that contains libmySQL.dll to your PATH (probably
    C:\Program Files\MySQL\MySQL Server 5.0\bin)
  3. If you are running your Rails app inside of a container such as
    RadRails :), make sure you restart your app container.

NOTE: Alternatively you could move the libmySQL.dll file to a directory
in your PATH like C:\ruby but this is unwise as you could re-break
things when you upgrade your Ruby installation).

Things seem to be much better now.

Wes

7

I did gem install mysql and got version 2.7.3.

Then when I restart Mongrel, I got this error:

“The procedure entry point mysql_stmt_row_tell could not be located in
the dynamic link library LIBMYSQL.dll.”

Did I miss something?

Wes