[sr-dev] MySQL - driver error on query: Commands out of sync; you can't run this command now

[marius zbihlei]

On 11/19/2010 12:24 AM, Johny Kadarisman Kwan wrote:
> Hi there,
>
> I'm running Kamilio 3.0.3, at least that is showen on sercmd>core.version.
>
> following are other details:
>
> Server: kamailio (3.0.3 (i386/linux)) a22dc9
> Mysql: 5.0.77
> CentOS 5.5
>
>
> On Thu, Nov 18, 2010 at 5:19 PM, Iñaki Baz Castillo<ibc at aliax.net>  wrote:
>    
>> 2010/11/18 Johny Kadarisman Kwan<jkr888 at gmail.com>:
>>      
>>> /usr/local/sbin/kamailio[11693]: ERROR: db_mysql [km_dbase.c:117]:
>>> driver error on query: Commands out of sync; you can't run this
>>> command now
>>>        
>> This error occurs when two MySQL requests sharing the same TCP
>> connection are sent one after the other, without waiting for the
>> response of the first one. This problem can arise when two threads or
>> two processes share the same MySQL connection and there is no a pool
>> mechanism or a lock mechanism.
>> This shouldn't occur in Kamailio as each process is supposed to
>> mantain its own MySQL connections, so it seems a bug. Which version
>> are you using?
>>
>>      

Hello
Google suggests that this seems to happen when you don't free the 
result, and then issue another query (highly dependent on MySQL client 
version etc).

"I think the real problem here is the order things happen in. A ROLLBACK 
or an AUTOCOMMIT query do not return a result set and thus do not need 
to be dealt with as you describe here. It is more likely that there is 
an existing result set that has not be explicitly freed in the PHP 
script and the PHP destructor for that result set is being called after 
the call to restore_connection_default. That's when you would get an 
out-of-sync error because the ROLLBACK is called with an outstanding 
result set. So, for those of you experiencing this problem, try 
explicitly calling mysql_free_result() on your result sets."

This is from a thread on a php bug (from 2002) 
http://bugs.php.net/bug.php?id=19529
Also this issue seem to plage some other known applications : 
http://forums.mysql.com/read.php?168,238786,238786 ;)

After looking thru the code of auth_db that generated the error it seems 
that the digest_authenticate() method doesn't explicitly  free the 
result when the call to get_ha1() succeeds. AFAIK this should not be a 
problem (as the result is freed a liter later on by db_mysql module) Any 
other ideas... ?

Marius
>> --
>>      
>> Iñaki Baz Castillo
>> <ibc at aliax.net>
>>
>>      
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