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mysql, number of TCP connections does not match on server / client machines
Posted by: gigi kent ()
Date: March 12, 2013 10:39AM

Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 419
Server version: 5.1.67-0ubuntu0.11.10.1 (Ubuntu)

jdbc-mysql.jar version: unknown - how do I check this ?

root@XMPP:/opt/tigase# java -version
java version "1.6.0_24"
OpenJDK Runtime Environment (IcedTea6 1.11.5) (6b24-1.11.5-0ubuntu1~11.10.1)
OpenJDK 64-Bit Server VM (build 20.0-b12, mixed mode)

As reported by netstat (client side) "show processlist" mysql command and netstat (server side). TCP state is "ESTABLISHED" on boths sides.

Server side (xx.xx.xx.241)

mysql> show processlist;
+-----+-------------+--------------------+----------+---------+------+-------+------------------+
| Id  | User        | Host               | db       | Command | Time | State | Info             |
+-----+-------------+--------------------+----------+---------+------+-------+------------------+
| 100 | tigase_user | xx.xx.xx.25:23820 | tigasedb | Sleep   |  921 |       | NULL             | 
| 101 | tigase_user | xx.xx.xx.25:23821 | tigasedb | Sleep   | 6664 |       | NULL             | 
| 102 | tigase_user | xx.xx.xx.25:23822 | tigasedb | Sleep   | 6664 |       | NULL             | 
| 103 | tigase_user | xx.xx.xx.25:23823 | tigasedb | Sleep   | 6664 |       | NULL             | 
| 104 | tigase_user | xx.xx.xx.25:23824 | tigasedb | Sleep   | 6664 |       | NULL             | 
| 105 | tigase_user | xx.xx.xx.25:23825 | tigasedb | Sleep   | 6664 |       | NULL             | 
| 106 | tigase_user | xx.xx.xx.25:23826 | tigasedb | Sleep   | 6664 |       | NULL             | 
| 107 | tigase_user | xx.xx.xx.25:23827 | tigasedb | Sleep   | 6654 |       | NULL             | 
| 108 | tigase_user | xx.xx.xx.25:23828 | tigasedb | Sleep   |  921 |       | NULL             | 
| 115 | tigase_user | xx.xx.xx.25:23835 | tigasedb | Sleep   | 6667 |       | NULL             | 
| 116 | tigase_user | xx.xx.xx.25:23836 | tigasedb | Sleep   | 6667 |       | NULL             | 
| 117 | tigase_user | xx.xx.xx.25:23837 | tigasedb | Sleep   | 6667 |       | NULL             | 
| 118 | tigase_user | xx.xx.xx.25:23838 | tigasedb | Sleep   | 6667 |       | NULL             | 
| 119 | tigase_user | xx.xx.xx.25:23839 | tigasedb | Sleep   | 6667 |       | NULL             | 
| 143 | tigase_user | xx.xx.xx.25:23864 | tigasedb | Sleep   |  921 |       | NULL             | 
| 144 | tigase_user | xx.xx.xx.25:23866 | tigasedb | Sleep   |  921 |       | NULL             | 
| 145 | tigase_user | xx.xx.xx.25:23867 | tigasedb | Sleep   |  654 |       | NULL             | 
| 153 | tigase_user | xx.xx.xx.25:23875 | tigasedb | Sleep   |  921 |       | NULL             | 
| 166 | tigase_user | xx.xx.xx.39:45214 | NULL     | Query   |    0 | NULL  | show processlist | 
+-----+-------------+--------------------+----------+---------+------+-------+------------------+
19 rows in set (0.00 sec)

Client side (xx.xx.xx.25):

root@XMPP:/opt/tigase# netstat -antop | grep "xx.xx.xx.241:3306" | wc -l
20
root@XMPP:/opt/tigase# netstat -antop | grep "xx.xx.xx.241:3306" 
tcp        0     74 xx.xx.xx.25:23846      xx.xx.xx.241:3306      ESTABLISHED 10222/java       on (75.60/12/0)
tcp        0    348 xx.xx.xx.25:23863      xx.xx.xx.241:3306      ESTABLISHED 10222/java       on (75.06/12/0)
tcp        0    348 xx.xx.xx.25:23829      xx.xx.xx.241:3306      ESTABLISHED 10222/java       on (75.06/12/0)
tcp        0      0 xx.xx.xx.25:23866      xx.xx.xx.241:3306      ESTABLISHED 10222/java       keepalive (5648.85/0/0)
tcp        0     74 xx.xx.xx.25:23845      xx.xx.xx.241:3306      ESTABLISHED 10222/java       on (79.66/12/0)
tcp        0     55 xx.xx.xx.25:23849      xx.xx.xx.241:3306      ESTABLISHED 10222/java       on (75.56/12/0)
tcp        0      0 xx.xx.xx.25:23870      xx.xx.xx.241:3306      ESTABLISHED 10222/java       keepalive (5648.83/0/0)
tcp        0     45 xx.xx.xx.25:23871      xx.xx.xx.241:3306      ESTABLISHED 10222/java       on (75.03/12/0)
tcp        0      0 xx.xx.xx.25:23868      xx.xx.xx.241:3306      ESTABLISHED 10222/java       keepalive (5648.82/0/0)
tcp        0      0 xx.xx.xx.25:23869      xx.xx.xx.241:3306      ESTABLISHED 10222/java       keepalive (5648.82/0/0)
tcp        0      0 xx.xx.xx.25:23875      xx.xx.xx.241:3306      ESTABLISHED 10222/java       keepalive (5665.19/0/0)
tcp        0      0 xx.xx.xx.25:23864      xx.xx.xx.241:3306      ESTABLISHED 10222/java       keepalive (5648.80/0/0)
tcp        0      0 xx.xx.xx.25:23872      xx.xx.xx.241:3306      ESTABLISHED 10222/java       keepalive (5648.79/0/0)
tcp        0      0 xx.xx.xx.25:23820      xx.xx.xx.241:3306      ESTABLISHED 10222/java       keepalive (962.67/0/0)
tcp        0     74 xx.xx.xx.25:23848      xx.xx.xx.241:3306      ESTABLISHED 10222/java       on (75.51/12/0)
tcp        0    348 xx.xx.xx.25:23874      xx.xx.xx.241:3306      ESTABLISHED 10222/java       on (74.99/12/0)
tcp        0     55 xx.xx.xx.25:23850      xx.xx.xx.241:3306      ESTABLISHED 10222/java       on (79.59/12/0)
tcp        0      0 xx.xx.xx.25:23828      xx.xx.xx.241:3306      ESTABLISHED 10222/java       keepalive (962.65/0/0)
tcp        0    228 xx.xx.xx.25:23873      xx.xx.xx..241:3306      ESTABLISHED 10222/java       on (83.17/12/0)
tcp        0      0 xx.xx.xx.25:23867      xx.xx.xx.241:3306      ESTABLISHED 10222/java       keepalive (5648.76/0/0)
As it can be seen, client shows 20 connections to the mysql server - which only shows 18 connections. Other time I have spotted a gap of 10 missing connections (10 reported at server vs 20 opened by client, or even a gap of 17: 22 client vs 5 server). The situation persists for some good minutes - not more than 15 I think - and then the number of connections starts to change (sometimes to the desired 20 / 20, but not sure how stable it stays there).

Connections are opened the regular way through Java code:

        conn = DriverManager.getConnection(db_conn);

They are not (explicitly) closed from client as they should always remain open. Db connection string:

--user-db-uri = jdbc:mysql://xx.xx.xx.241/tigasedb?user=tigase_user&password=*****&useUnicode=true&characterEncoding=UTF8

my.cnf:

root@TDB:~# egrep "^[^#]." /etc/mysql/my.cnf 
[client]
port        = 3306
socket      = /var/run/mysqld/mysqld.sock
default-character-SET=utf8
[mysqld_safe]
socket      = /var/run/mysqld/mysqld.sock
nice        = 0
[mysqld]
user        = mysql
socket      = /var/run/mysqld/mysqld.sock
port        = 3306
basedir     = /usr
datadir     = /var/lib/mysql
tmpdir      = /tmp
skip-external-locking
bind-address        = 0.0.0.0
key_buffer      = 16M
max_allowed_packet  = 16M
thread_stack        = 192K
thread_cache_size       = 8
myisam-recover         = BACKUP
query_cache_limit   = 1M
query_cache_size        = 16M
log_error                = /var/log/mysql/error.log
expire_logs_days    = 10
max_binlog_size         = 100M
init_connect='SET collation_connection = utf8_general_ci; SET NAMES utf8;'
character-set-server=utf8
collation-server=utf8_general_ci
skip-character-set-client-handshake
[mysqldump]
quick
quote-names
max_allowed_packet  = 16M
[mysql]
[isamchk]
key_buffer      = 16M
!includedir /etc/mysql/conf.d/

And there are also lots of reports of

Caused by: com.mysql.jdbc.exceptions.MySQLTimeoutException: Statement cancelled due to timeout or client request

and

Caused by: java.sql.SQLException: Query execution was interrupted

What is going on here ? Thank you!

Options: ReplyQuote


Subject Written By Posted
mysql, number of TCP connections does not match on server / client machines gigi kent 03/12/2013 10:39AM
Re: mysql, number of TCP connections does not match on server / client machines Todd Farmer 03/13/2013 02:41PM
Re: mysql, number of TCP connections does not match on server / client machines gigi kent 03/15/2013 02:55AM
Re: mysql, number of TCP connections does not match on server / client machines gigi kent 03/20/2013 02:08AM


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