As was found out in "Kamailio stops processing requests over UDP"
thread, db_mysql_submit_query() in some circumstances hangs when it
executes mysql_ping here:
if (my_ping_interval) {
t = time(0);
if ((t - CON_TIMESTAMP(_h)) > my_ping_interval) {
for (i=0; i < (db_mysql_auto_reconnect ? 3 : 1); i++) {
if (mysql_ping(CON_CONNECTION(_h))) {
LM_INFO("driver error on ping: %s\n",
mysql_error(CON_CONNECTION(_h)));
counter_inc(mysql_cnts_h.driver_err);
} else {
break;
}
}
}
...
}
Comment in front of db_mysql_submit_query() function tells:
* Send a SQL query to the database server. This methods tries to reconnect
* to the server if the connection is gone and the auto_reconnect parameter is
* enabled. It also issues a mysql_ping before the query to connect again after
* a long waiting period because for some older mysql versions the auto
reconnect
* don't work sufficient. If auto_reconnect is enabled and the server supports
it,
* then the mysql_ping is probably not necessary, but its safer to do it in this
* cases too.
*
The text was most likely written many years ago and auto reconnect now
works OK in mysql versions in use today.
I would like to test if the hangup could be prevented without the above
code. Would it be possible to make the code optional via a compilation
flag or by some other means?
-- Juha
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