CP/MySQLdb reports "MySQL server has gone away" but it hasn't !

Hi - Recently i started running my development CP server as
follows ...

nohup nice python cposerver.py  >
/home/rshea/cposerver_print_out.txt &

... in order that it should remain active once i had logged
off.

I now find that when there has been no activity for a while
i get an
error from within CP which originates from MySQLdb - 
'MySQL server has
gone away'.

Now if I log on and run mysql from the prompt i can access
the database
as normal so can anyone explain why i get this message ?

By the way the message will go away if i stop and restart
the server

I know the message is associated with MySQL being out of use
for some
time but what i don't understand is (A) how i can stop it
happening
(basically to tell MySQL "I don't care how long you
have to wait until
you hear from me, keep listening !") and (B) why CP
requires a restart
to acknowledge that MySQL is available.

Any information gratefully received.

thanks

richard.

ps - environment is MySQL 5.x, Gentoo is the OS, CP 2.1.1


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On 3/28/06, northof40 <shearichardgmail.com> wrote:
> I now find that when there has been no activity for a
while i get an
> error from within CP which originates from MySQLdb - 
'MySQL server has
> gone away'.

Well it does look like the MySQL connection needs refreshing
from time
to time because I get something similar.  If I try to use my
web-app
if it has not been accessed for a day or two, I get (last
two lines of
traceback):

  File
"D:\Python24\Lib\site-packages\MySQLdb\connection
s.py", line
33, in defaulterrorhandler
    raise errorclass, errorvalue
OperationalError: (2013, 'Lost connection to MySQL server
during query').

If I then retry it works (without me having to restart
anything).   
I'd say this isn'nt MySQLdb's or CherryPy's fault,
because something
similar happens if I leave the MySQL command prompt client
running and
try to reuse it after a day or two.

So I intend to follow this thread the recent thread
"Running Scheduled
functions in Cherrypy ", and write some kind of
database connection
keepalive function

The  Scheduled functions - thread is
at:http://groups.google.co
m/group/cherrypy-users/browse_thread/thread/8b89e9af50254247
?hl=en

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You really should avoid keeping a connection open for that
long, and if
you don't have a lot of db-interactions it's better to
close it and get
a new one for every operation.  But an even better solution
is keeping
a connection pool, and for every db-operation (every
transaction, at
least) get a connection from the pool and return it, then
make sure the
connection pool gets rid of connections which have expired.
The expiry
time can be found in the mysql-config.

An example pool can be found here:

http:/subpar.se/pool.py


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> An example pool can be found here:
> http:/subpar.se/pool.py

This is not how a 'pool' works.

This code merely instantiates a bunch of objects then it
uses them up
one by one (the get method removes  from the queue), after
that it
alwas creates a new instance.


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