Re: vmysql: sql error[3]: MySQL server has gone away

On 13/05/2010 15:37, Joe Littleton wrote:
>
> I have searched for two days trying to figure out why I keep getting 
> this error. I am using vpopmail 5.4.30 and mysql 5.0.77-4 on CentOS 5.4
>
> I can reproduce the error by restarting the mysql server. The only way 
> to make it work after restarting mysql is to also restart authdaemond.
>
> I did find some info on the mailing list that says:
>
> To describe the problem: when you run vpopmail in MySQL mode, with
> courier-authdaemond and MySQL v5.0 or later, you will find that for the first 8
> hours, everything works just fine, but after 8 hours, nobody will be able to
> authenticate to the email server and you will see "MySQL server has gone away"
> errors in the maillog.
>   
> The cause of the problem is that in MySQL 5.0 (and probably some 4.1 releases),
> MySQL implements a new timeout definition for connections, a timeout that
> ignores traffic.  This timeout will shut down the socket thread from the MySQL
> side.  The problem is that the client (vchkpw and friends) do not
> know/understand about this timeout and socket termination so they continue on
> in ignorate bliss until they try to send to the socket and find that it's no
> longer valid - literally "the server has gone away".
>
> And a patch is offered but the version of vpop that I am running 
> already has that patch installed.
>
> Anyone else have any ideas?
>
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>    
>  
Hi!

I had a similar problem and it was being caused by excess tuning to 
mysql. Now I run my mysql with this my.cnf

The issue was not with vpopmail but with web applications. A few years 
ago I had a mysqld has gone away but it was because a small 
max_connection value.

max_connections = 75 <-------------------- what is your number of max conn?
key_buffer = 120M
max_allowed_packet = 24M
table_cache = 3072
sort_buffer_size = 2M
read_buffer_size = 2M
read_rnd_buffer_size = 4M
myisam_sort_buffer_size = 64M
thread_cache_size = 8
query_cache_size = 128M
query_cache_limit = 2M
join_buffer_size = 1M
thread_concurrency = 2
long_query_time = 5
log-slow-queries = /tmp/slow-queries.log
open_files_limit = 6500
max_heap_table_size = 64M
query_cache_min_res_unit = 2K
wait_timeout = 60 <------------------- Watch this value it was giving my 
headache
connect_timeout = 10 <------------------- Watch this value it was giving 
my headache
interactive_timeout = 120 <------------------- Watch this value it was 
giving my headache
max_connect_errors = 1000 <------------------- Watch this value it was 
giving my headache
expire_logs_days = 7
low_priority_updates = 1
max_join_size = 4294967295

This is a dedicated server with 2G, so the others values my not apply to 
your setup.

Hope that helps.
sergio rosa

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