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MySQL crashing --open-files-limit=50000 error / --skip-name-resolve

Discussion in 'Workarounds and Optimization' started by go4, Oct 21, 2015.

  1. go4

    go4 Member

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    Hi,

    Trying to track down MySQL issues on a VPS that has around 65 accounts, 78 databases. New to this so any help appreciated.

    So two things I can see (that may or may not be related).

    1. Open files limit

    Process Manager constantly shows

    Code:
    /usr/sbin/mysqld --basedir=/usr --datadir=/var/lib/mysql --plugin-dir=/usr/lib64/mysql/plugin --user=mysql --log-error=/var/lib/mysql/xxxx.err --open-files-limit=50000 --pid-file=/var/lib/mysql/xxx.pid --socket=/var/lib/mysql/mysql.sock --port=xxx
    Could increase open files limit but it seems unlikely we should have 50000 open files?

    2. --skip-name-resolve errors

    We're getting LOTS of --skip-name-resolve errors in logs. Logs show intense periods where around 1000 entries appear with exactly the same timestamp, the first 500 showing [Warning] 'user' entry '-' ignored in --skip-name-resolve mode then another 500 corresponding db/user entries showing [Warning] 'db' entry...

    Code:
    151021 19:16:40 [Warning] 'user' entry 'xxx_xxx@xxx.xxx.com' ignored in --skip-name-resolve mode.
    + another 500 lines

    Code:
    151021 19:16:40 [Warning] 'db' entry 'xxx\xxx xxx@xxx.xxx.com' ignored in --skip-name-resolve mode.
    + another 500 lines

    Thanks.

    Server info
    Code:
    /etc/redhat-release:CentOS release 6.7 (Final)
    /usr/local/cpanel/version:11.52.0.17
    /var/cpanel/envtype:xen pv
    CPANEL=release
    Server version: Apache/2.2.27 (Unix)
    Server built:   Jul 17 2014 06:46:24
    Cpanel::Easy::Apache v3.26.0 rev9999
    PHP 5.4.30 (cli) (built: Jul 17 2014 06:54:51)
    Copyright (c) 1997-2014 The PHP Group
    Zend Engine v2.4.0, Copyright (c) 1998-2014 Zend Technologies
        with the ionCube PHP Loader v4.6.1, Copyright (c) 2002-2014, by ionCube Ltd., and
        with Zend Guard Loader v3.3, Copyright (c) 1998-2013, by Zend Technologies
    mysql  Ver 14.14 Distrib 5.5.45, for Linux (x86_64) using readline 5.1
     
  2. cPanelMichael

    cPanelMichael Forums Analyst
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    Hello :)

    Do you notice any specific entries in the MySQL error log (/var/lib/mysql/$hostname.err) just before it crashes (other than the warning messages you posted)?

    Thank you.
     
  3. go4

    go4 Member

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    Thanks cPanelMichael,

    Appreciate your help.

    To clairify what I mean when I say crash: although from the frontend we're getting "Cannot connect to database" and everything going down the xxx.err log doesn't show a crash.

    What I can see in the log though is that instantly on restart those --skip-name-resolve ignored errors start up, hundreds of lines logging at the same second restart completes.

    Code:
    150927 19:25:09 mysqld_safe Number of processes running now: 0
    150927 19:25:12 mysqld_safe mysqld restarted
    150927 19:25:13 [Warning] 'THREAD_CONCURRENCY' is deprecated and will be removed in a future release.
    150927 19:25:13 [Note] Plugin 'FEDERATED' is disabled.
    150927 19:25:13 InnoDB: The InnoDB memory heap is disabled
    150927 19:25:13 InnoDB: Mutexes and rw_locks use GCC atomic builtins
    150927 19:25:13 InnoDB: Compressed tables use zlib 1.2.3
    150927 19:25:13 InnoDB: Using Linux native AIO
    150927 19:25:14 InnoDB: Initializing buffer pool, size = 128.0M
    150927 19:25:14 InnoDB: Completed initialization of buffer pool
    150927 19:25:14 InnoDB: highest supported file format is Barracuda.
    InnoDB: The log sequence number in ibdata files does not match
    InnoDB: the log sequence number in the ib_logfiles!
    150927 19:25:14  InnoDB: Database was not shut down normally!
    InnoDB: Starting crash recovery.
    InnoDB: Reading tablespace information from the .ibd files...
    InnoDB: Restoring possible half-written data pages from the doublewrite
    InnoDB: buffer...
    150927 19:25:23  InnoDB: Waiting for the background threads to start
    150927 19:25:24 InnoDB: 5.5.42 started; log sequence number 3135004108
    150927 19:25:24 [Note] Server hostname (bind-address): '0.0.0.0'; port: 3306
    150927 19:25:24 [Note]   - '0.0.0.0' resolves to '0.0.0.0';
    150927 19:25:24 [Note] Server socket created on IP: '0.0.0.0'.
    150927 19:25:24 [Warning] 'user' entry 'xx@xx' ignored in --skip-name-resolve mode.
    150927 19:25:24 [Warning] 'user' entry 'xx@xx' ignored in --skip-name-resolve mode.
    150927 19:25:24 [Warning] 'user' entry 'xx@x'x ignored in --skip-name-resolve mode.
    150927 19:25:24 [Warning] 'user' entry 'xx@xx' ignored in --skip-name-resolve mode.
    ...etc etc etc...
     
  4. anton_latvia

    anton_latvia Well-Known Member
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    is that end? Does MySQL server operate normally afterwards? open-files-limits can be lowered.
     
    #4 anton_latvia, Oct 27, 2015
    Last edited by a moderator: Oct 27, 2015
  5. go4

    go4 Member

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    Thanks anton,

    No afterwards we straight away get hundreds of those
    [Warning] 'user' entry 'xx@xx' ignored in --skip-name-resolve mode entries and then always in Process Manager

    Code:
    /usr/sbin/mysqld --basedir=/usr --datadir=/var/lib/mysql --plugin-dir=/usr/lib64/mysql/plugin --user=mysql --log-error=/var/lib/mysql/xxx.com.err --open-files-limit=50000 --pid-file=/var/lib/mysql/xxx.com.pid --socket=/var/lib/mysql/mysql.sock --port=3306
     
  6. anton_latvia

    anton_latvia Well-Known Member
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