今天mysql備份的crontab自動運行的時候,出現了報警,報警內容如下
mysqldump: Error 2013: Lost connection to MySQL server during query when dumping table `file_storage` at row: 29 mysqldump: Couldn't execute 'show table status like 'property'': MySQL server has gone away (2006) mysqldump: Couldn't execute 'SET OPTION SQL_QUOTE_SHOW_CREATE=1': MySQL server has gone away (2006) mysqldump: Couldn't execute 'show fields from `property`': MySQL server has gone away (2006) mysqldump: Couldn't execute 'show table status like 'revision'': MySQL server has gone away (2006) mysqldump: Couldn't execute 'SET OPTION SQL_QUOTE_SHOW_CREATE=1': MySQL server has gone away (2006) mysqldump: Couldn't execute 'show fields from `revision`': MySQL server has gone away (2006) mysqldump: Couldn't execute 'show table status like 'revision\_change'': MySQL server has gone away (2006) mysqldump: Couldn't execute 'SET OPTION SQL_QUOTE_SHOW_CREATE=1': MySQL server has gone away (2006) mysqldump: Couldn't execute 'show fields from `revision_change`': MySQL server has gone away (2006) mysqldump: Couldn't execute 'show table status like 'setting'': MySQL server has gone away (2006) mysqldump: Couldn't execute 'SET OPTION SQL_QUOTE_SHOW_CREATE=1': MySQL server has gone away (2006) mysqldump: Couldn't execute 'show fields from `setting`': MySQL server has gone away (2006) mysqldump: Couldn't execute 'show table status like 'setting\_history'': MySQL server has gone away (2006) mysqldump: Couldn't execute 'SET OPTION SQL_QUOTE_SHOW_CREATE=1': MySQL server has gone away (2006) mysqldump: Couldn't execute 'show fields from `setting_history`': MySQL server has gone away (2006) mysqldump: Couldn't execute 'show table status like 'user'': MySQL server has gone away (2006) mysqldump: Couldn't execute 'SET OPTION SQL_QUOTE_SHOW_CREATE=1': MySQL server has gone away (2006) mysqldump: Couldn't execute 'show fields from `user`': MySQL server has gone away (2006)
一開始我把故障的錯誤點定位在"mysqldump: Couldn't execute 'show fields from `revision`': MySQL server has gone away (2006)"這段報錯上面,網上的部分建議是檢查max_allowed_packet的值,然后改得盡量大一些,我查看當前的值信息如下:
mysql> show global variables like 'max_allowed_packet'; +--------------------+-----------+ | Variable_name | Value | +--------------------+-----------+ | max_allowed_packet | 268435456 | +--------------------+-----------+ 1 row in set (0.00 sec)
可以看到當前的值已經是200M了,說明應該不是這個問題導致的,而且查看報錯,這里並沒有從select獲取大量數據,也沒有insert或者update大量數據.
我重新運行了一下腳本,過會兒又出現了相同的報錯了.
后來注意到有這么一段
mysqldump: Error 2013: Lost connection to MySQL server during query when dumping table `file_storage` at row: 29
在一篇文章里看到了針對這個報錯的解決措施
https://ottomatik.groovehq.com/knowledge_base/topics/solving-error-2013-lost-connection-to-mysql-server-during-query-when-dumping-table
后來將timeout的值調大以后,就可以正常dump了
mysql> show global variables like '%timeout%'; +----------------------------+-------+ | Variable_name | Value | +----------------------------+-------+ | connect_timeout | 10 | | delayed_insert_timeout | 300 | | innodb_lock_wait_timeout | 100 | | innodb_rollback_on_timeout | OFF | | interactive_timeout | 28800 | | net_read_timeout | 30 | | net_write_timeout | 60 | | slave_net_timeout | 3600 | | table_lock_wait_timeout | 200 | | wait_timeout | 28800 | +----------------------------+-------+ 10 rows in set (0.00 sec) mysql> set global net_read_timeout = 120; Query OK, 0 rows affected (0.03 sec) mysql> set global net_write_timeout = 900; Query OK, 0 rows affected (0.00 sec) mysql> show global variables like '%timeout%'; +----------------------------+-------+ | Variable_name | Value | +----------------------------+-------+ | connect_timeout | 10 | | delayed_insert_timeout | 300 | | innodb_lock_wait_timeout | 100 | | innodb_rollback_on_timeout | OFF | | interactive_timeout | 28800 | | net_read_timeout | 120 | | net_write_timeout | 900 | | slave_net_timeout | 3600 | | table_lock_wait_timeout | 200 | | wait_timeout | 28800 | +----------------------------+-------+ 10 rows in set (0.00 sec)