MySQL sudden restart I have a strange issue with my MySQL server. It suddenly restarts. It's a rare but very big problem for me.

This server is running as Master in Master-Slave replication.
I'm using MySQL 5.6.16-1+sury.org~precise+1-log

In syslog I see next info:

Jun  4 10:53:32 localhost kernel: [18821099.786264] init: mysql main process (25937) terminated with status 1
Jun  4 10:53:32 localhost kernel: [18821099.786329] init: mysql main process ended, respawning
Jun  4 10:53:32 localhost kernel: [18821100.064250] type=1400 audit(1433404412.925:26): apparmor="STATUS" operation="profile_replace" name="/usr/sbin/mysqld" pid=9957 comm="apparmor_parser"


I see no errors in mysql common error files. I use Ubuntu 12.04 LTS, there is 32G of RAM on the server. Here is the config

[client]
port            = 3306
socket          = /var/run/mysqld/mysqld.sock

[mysqld_safe]
socket          = /var/run/mysqld/mysqld.sock
nice            = 0

[mysqld]
user            = mysql
pid-file        = /var/run/mysqld/mysqld.pid
socket          = /var/run/mysqld/mysqld.sock
port            = 3306
basedir         = /usr
datadir         = /var/lib/mysql
tmpdir          = /tmp
lc-messages-dir = /usr/share/mysql

query_cache_type = 1
innodb_buffer_pool_size = 9500M
max_heap_table_size = 268435456
tmp_table_size = 268435456
query_cache_size = 512M
sort_buffer_size = 8388608

innodb_additional_mem_pool_size = 16M
innodb_log_file_size = 32M
innodb_flush_log_at_trx_commit = 2
innodb_flush_method = 'O_DIRECT'
skip-external-locking
low-priority-updates
skip-name-resolve

key_buffer              = 16M
max_allowed_packet      = 16M
thread_stack            = 192K
thread_cache_size       = 8
myisam-recover         = BACKUP
max_connections        = 600
query_cache_limit       = 4M
log_bin                 = /var/lib/mysql/mysql-bin
binlog_format           = MIXED
expire_logs_days        = 7
max_binlog_size         = 100M
binlog-do-db            = db1
binlog-do-db            = db2
binlog-do-db            = db3

server-id               = 1355115082

max_binlog_size         = 100M

[mysqldump]
quick
quote-names
max_allowed_packet      = 16M

[isamchk]
key_buffer              = 16M


Could you please help me with this problem or give some advice to think about?

Thank you in advance!
Today I found new logs at /var/log/upstart

So, terminating with signal 1 was the after effect but not the cause.

I saw next information 

It is possible that mysqld could use up to
key_buffer_size + (read_buffer_size + sort_buffer_size)*max_threads = 5016582 K  bytes of memory
Hope that's ok; if not, decrease some variables in the equation.


So, I do assume, that the reason was in memory excess. Thus, I decreased max_threads (actually, it's the max_connections parameter) to have a security delta of memory.