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•Table and record locks held by active transactions 

•Pending I/O operations and related statistics 

•Insert buffer and adaptive hash index statistics 

•Redo log data 

•Buffer pool statistics 

•Row operation data 

•The InnoDB  Lock Monitor prints additional lock information as part of the standard InnoDB  Monitor output. 

## 15.17.2 Enabling InnoDB Monitors 

When InnoDB  monitors are enabled for periodic output, InnoDB  writes the output to mysqld  server standard error output ( stderr ) every 15 seconds, approximately. 

InnoDB  sends the monitor output to stderr  rather than to stdout  or fixed-size memory buffers to avoid potential buffer overflows. 

On Windows, stderr  is directed to the default log file unless configured otherwise. If you want to direct the output to the console window rather than to the error log, start the server from a command prompt in a console window with the --console  option. For more information, see Default Error Log Destination on Windows. 

On Unix and Unix-like systems, stderr  is typically directed to the terminal unless configured otherwise. For more information, see Default Error Log Destination on Unix and Unix-Like Systems. 

InnoDB  monitors should only be enabled when you actually want to see monitor information because output generation causes some performance decrement. Also, if monitor output is directed to the error log, the log may become quite large if you forget to disable the monitor later. 

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## Note 

To assist with troubleshooting, InnoDB  temporarily enables standard InnoDB Monitor output under certain conditions. For more information, see Section 15.21, “InnoDB Troubleshooting” . 

InnoDB  monitor output begins with a header containing a timestamp and the monitor name. For example: 

===================================== 2014-10-16 18:37:29 0x7fc2a95c1700 INNODB MONITOR OUTPUT ===================================== 

The header for the standard InnoDB  Monitor ( INNODB MONITOR OUTPUT ) is also used for the Lock Monitor because the latter produces the same output with the addition of extra lock information. 

The innodb_status_output  and innodb_status_output_locks  system variables are used to enable the standard InnoDB  Monitor and InnoDB  Lock Monitor. 

## Enabling the Standard InnoDB Monitor 

The PROCESS  privilege is required to enable or disable InnoDB  Monitors. 

Enable the standard InnoDB  Monitor by setting the innodb_status_output  system variable to ON . 

