SIGPIPE crash when request is more than 4MB - mysql

Question

I use Xcode 3.2.1 (I am on snow leopard for some reasons) with mysql :
Server version: 5.6.15 MySQL Community Server (GPL) +
mysql-connector-c-6.1.3-osx10.6-x86_64
I am passing a request to mysql_query() as follows.
// mysql request
request = [NSString stringWithFormat:#"UPDATE consult SET summary='%#', pheno='%#' WHERE idConsult=%#", sum, phe, idc];
if (mysql_query(mysqlCnx,[request UTF8String])) {
db_finish_with_error(mysqlCnx);
}
When the request size is more than 4MB, I get a SIGPIPE with the following stack trace :
#0 0x7fff896d791e in sendto
#1 0x100065a92 in vio_write
#2 0x10004d2a2 in net_write_packet
#3 0x10004d3ac in net_write_buff
#4 0x10004d6e2 in net_write_command
#5 0x100048e3c in cli_advanced_command
#6 0x100046bdd in mysql_real_query
#7 0x1000093f9 in -[ConsultList mysqlUpdateResumePhenoFields:] at ConsultList.m:163
4#8 0x10000a565 in -[ConsultList okConsult:] at ConsultList.m:367
Any known issue ?

Answer 1

Here was the solution :
/etc/my.cnf
[mysqld]
max_allowed_packet=120M
as root :
chown 644 /etc/my.cnf
mysql> set global max_allowed_packet = 125829120;
Query OK, 0 rows affected (0,00 sec)
mysql> show variables like 'max_allowed_packet';
+--------------------+-----------+
| Variable_name | Value |
+--------------------+-----------+
| max_allowed_packet | 125829120 | << 120MB !
+--------------------+-----------+