Mysql client common exception analysis

SocketTimeoutException

jdbc timeout包括Transaction Timeout/Statement Timeout/connectTimeout/socketTimeout四种类型,详细解释可见Jdbc & Mysql timeout分析

如果与服务器连接成功,The data transfer starts.如果服务器处理数据用时过长,超过了socketTimeout,就会抛出SocketTimeOutExceptin,即服务器响应超时

建议在jdbc url param中显示配置connectTimeout/socketTimeout,有效控制MySQL处理时间,并释放连接

jdbc:mysql://127.0.0.1:3306/test?useUnicode=true&characterEncoding=UTF-8&zeroDateTimeBehavior=convertToNull&autoReconnect=true&connectTimeout=3000&socketTimeout=5000

CommunicationsException

若发生 com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure 异常,Failed to connect to the database,But there can be multiple reasons for failure,roughly the same mysql 各种 timeout 参数相关

EOFException

net_write_timeout 控制 mysql serverTimeout for writing data to the client.If the client establishes a connection,超过该时间MySQLData has not been written yet,则会抛出EOFException

java.io.EOFException: Can not read response from server. Expected to read 34328 bytes, read 433 bytes before connection was unexpectedly lost.

SocketException

jdbcConnection will be based on mysql wait_timeout 检测空闲连接.若在 wait_timeout 时间内,The connection is still idle,mysql serverThis link will be broken.

与MySQL建立连接成功后,MySQL主动断开连接,The underlying exception isjava.net.SocketException: Software caused connection abort: recv failed

SocketTimeoutException

sql执行时间超过socketTimeout的配置,则会抛出java.net.SocketTimeoutException: Read timed out

RecoverableDataAccessException

Disconnected is usedMySQL连接,会抛出org.springframework.dao.RecoverableDataAccessException

附表(MySQL timeout参数)

SHOW VARIABLES LIKE '%timeout%';可查看MySQL timeout参数

参数	描述	功能
connect_timeout	连接响应超时时间	服务器端在这个时间内如未连接成功,则会返回连接失败.
wait_timeout	连接空闲超时时间	与服务器端无交互状态的连接,直到被服务器端强制关闭而等待的时间.It can be considered as the idle time of the server-side connection,If idle for more than this time, it will automatically shut down
interactive_timeout	连接空闲超时时间	与服务器端无交互状态的连接,直到被服务器端强制关闭而等待的时间.
net_read_timeout	数据读取超时时间	before terminating the read,The number of seconds to wait to get data from a connection;When the service is reading data from the client,net_read_timeoutControls when to time out.That is, the client performs data reading,How many seconds to wait for automatic disconnection if still unsuccessful.
net_write_timeout	数据库写超时时间	和net_read_timeout意义类似,before terminating the write,How many seconds to waitblockWrite to the connection;When the service is writing data to the client,net_write_timeoutControls when to time out.
slave-net-timeout	The time to delay synchronization from the library	当slavethink connectedmasterwhen there is a problem with the connection,就等待N秒,然后断开连接,重新连接master

interactive_timeout和wait_timeoutThe meaning is the same though,But there are essential differences in using objects.interactive_timeout针对交互式连接（比如通过mysql客户端连接数据库）,wait_timeout针对非交互式连接（Like generallyPHP中使用PDO连接数据库,当然你可以设置CLIENT_INTERACTIVE选项来改变）.所谓的交互式连接,即在mysql_real_connect()函数中使用了CLIENT_INTERACTIVE选项.

• slave-net-timeoutWorks on slave libraries when master-slave is synchronized;
• connect_timeout：在获取连接阶段起作用;
• interactive_timeout和wait_timeout：Works during connection idle phase;
• net_read_timeout和net_write_timeout：It works when the connection is executed.

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参考文档：

1. JDBC未设置socketThe timeout caused the application's thread pool to block
2. Database related exception analysis