Wednesday, April 15, 2009

Warning Aborted connection, log_warnings and wait_timeout


In my server error log i see

090415 10:55:57 [Warning] Aborted connection 481 to db: 'db' user: 'user' host: 'localhost' (Got timeout reading communication packets)
090415 10:56:16 [Warning] Aborted connection 582 to db: 'db' user: 'user' host: 'localhost' (Got timeout reading communication packets)
090415 11:05:13 [Warning] Aborted connection 2693 to db: 'db' user: 'root' host: 'localhost' (Got timeout reading communication packets)


every thread connected to mysql and sleep more than wait_timeout mysql will close it.

the previous warning depend on log_warnings level, by default log_warnings = 1, if its =2 all the closed connection will written in mysql error log.

I think we don't need this warning.;)

--log-warnings[=level], -W [level]

Option Sets Variable Yes, log-warnings
Variable Name log_warnings
Variable Scope Both
Dynamic Variable Yes
Disabled by skip-log-warnings
Value Set Type numeric
Default 1

Print out warnings such as Aborted connection... to the error log. Enabling this option is recommended, for example, if you use replication (you get more information about what is happening, such as messages about network failures and reconnections). This option is enabled (1) by default, and the default level value if omitted is 1. To disable this option, use --log-warnings=0. If the value is greater than 1, aborted connections are written to the error log. See Section B.1.2.11, “Communication Errors and Aborted Connections”.

If a slave server was started with --log-warnings enabled, the slave prints messages to the error log to provide information about its status, such as the binary log and relay log coordinates where it starts its job, when it is switching to another relay log, when it reconnects after a disconnect, and so forth.



wait_timeout

The number of seconds the server waits for activity on a non-interactive connection before closing it. This timeout applies only to TCP/IP and Unix socket file connections, not to connections made via named pipes, or shared memory.

On thread startup, the session wait_timeout value is initialized from the global wait_timeout value or from the global interactive_timeout value, depending on the type of client (as defined by the CLIENT_INTERACTIVE connect option to mysql_real_connect()). See also interactive_timeout.

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