MySQL optimization or why the server is worsened

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  • MySQL optimization or why the server is worsened


    Please advise me how can I optimize my MySQL server. Or advise which way to look. Maybe someone had similar problems?

    Over the past two weeks the MySQL server dropped 2 times. I began searching for ways to optimize the server.

    Overall the picture like that:

    There is a separate MySQL server (Debian), it stores the information for the call center built on top of the Asterisk open source IP PBX (separate server). Almost all information of the call center stored in the MySQL: call queues, agents, IVR values, CDR etc. The Asterisk constantly interacts with the MySQL server to get or to put info. Average number of phone calls for the system is about 70 calls simultaneously.

    Recently I observed a delay of the redistribution of clients for a free call center agents. A delay was increased from 5 second up to 60 seconds and sometimes even more. I suspected InnoDB locks and transactions deadlocks. And then the MySQL server started falling.

    In SHOW ENGINE INNODB STATUS\G I see a lot of locks and transactions that hang over 40 sec but I can not figure out hot to deal with them. And is it necessary?

    2721452-*** (2) TRANSACTION:

    2721453:TRANSACTION 0 1345044118, ACTIVE 45 sec, process no 23678, OS thread id 140176187664128 starting index read, thread declared inside InnoDB 0

    2721454-mysql tables in use 1, locked 1

    2721455-10 lock struct(s), heap size 3024, 7 row lock(s), undo log entries 2

    Also in the output is a bunch of information but I do not know what conclusions could be made for those values. Please look and tell me what values are most suspicious on your point of view.

    Complete log of half a month can be found in the file *show_engine_innodbAndProc_stat_10Apr2013

    Peak CPU load by mysqld is quit high as can be seen from the graphs. Memory and disk are not heavily loaded. See all the graphics in *graphs

    The list of MySQL tables and their engines can be seen in *mysql_engines

    MySQL global variables in *mysqlGvars.txt

    The MySQL server hardware settings in *phys_mysql_server

    *All files can be downloaded by the link [URL="http://rapidshare.com/files/3386491301/alldata.zip"]http://rapidshare.com/files/3386491301/alldata.zip[/URL="http://rapidshare.com/files/3386491301/alldata.zip"]

  • #2
    I think you should start by focusing on those things:

    - You have default value of innodb_log_file_size - 5MB per each. This is really bad setting for write performance in InnoDB. You should change to like 256MB, or more if you upgrade from MySQL 5.1 to 5.5 (due to InnoDB recovery speed).

    - I can see pretty suspicious queries in processlist snapshots:

    SELECT login, name, extension FROM pbx.operators WHERE uid IN (SELECT uid FROM pbx.group_abon WHERE gid IN (SELECT gid FROM pbx.groups WHERE userfield IN (5) GROUP BY gid) GROUP BY uid)


    SELECT `id`, `login`, `state`, `login_date`, `timestamp` FROM pbx.callcenter WHERE stat='1' AND `login` IN (SELECT `login` FROM pbx.operators WHERE `uid` IN (SELECT `uid` FROM pbx.group_abon WHERE `gid` IN (6205, 6206, 6207) AND gid LIKE '%')) ORDER BY login_date

    You should check their query plan with EXPLAIN, those queries might need to be rewritten.

    - Another thing is that you use MyISAM engine for most of your tables. Note that MyISAM doesn't really scale much and your decent hardware with 16-cores Xeon won't help much under high concurrent load. Not mentioning of all other differences between MyISAM and InnoDB. So I think you should consider moving to InnoDB.
    Here is some lecture you might be insterested in: