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JYelton
Asked: 2011-02-16 12:34:43 +0800 CST

Is it normal for mysqld to have 32k handles?

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I am running Wampserver 2.0i on Windows 7 64-bit.

I'm not experiencing any problems with any of the processes, but I noticed that mysqld is maintaining over 32,000 open handles. Is this normal behavior for this process?

I am also running MS SQL Server, and its process (sqlservr) only has 400+ handles.

mysql windows-7

1 Answers

  1. Best Answer

    For MyISAM, each tabble is comprised of .frm, .MYD, and .MYI. That's three files handles per MyISAM table.

    Temporary Files in MyISAM can be opend and closed frequently.

    For InnoDB (ACID Complaint Storage Engine) there can be that many threads.

    The InnoDB buffer pool to manage.

    If innodb_file_per_table is off you have threads for the following:
    Reading/updating the metadata in ibdata1
    Reading/updating data pages in ibdata1
    Reading/updating index pages in ibdata1
    Reading/updating MVCC (Multiversioning Concurrency Control) data in ibdata1
    Reading/updating MVCC data in ibdata1 in ib_logile0 and ib_logile1 (Redo Log Info)

    If innodb_file_per_table is on you have threads for the following:
    Reading/updating the metadata in ibdata1
    Reading/updating data pages in .ibd files
    Reading/updating index pages in .ibd files
    Reading/updating MVCC (Multiversioning Concurrency Control) data in ibdata1
    Reading/updating MVCC data in ibdata1 in ib_logile0 and ib_logile1 (Redo Log Info)

    As long as nothing broken, you are fine.

    I would recommend the following reading for you on this one:

    MySQL 5.0 Certification Study Guide
    ISBN 0-672-32812-7
    Chapter 23 Pages 355-357 Section 23.5 : How MySQL Uses Memory
    Chapter 29 Pages 408-412 Section 29.2 : The MyISAM Engine
    Chapter 29 Pages 414-432 Section 29.4 : The InnoDB Engine

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