Java BoneCP MySQL连接超时

Question

我有一个应用程序设置为与BoneCP共享mysql连接。 目前，该应用程序并未得到大量使用，因此连接的使用频率不高。 一段时间后，曾经有效的查询开始失败，并且我收到类似以下消息：

com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure

The last packet successfully received from the server was 2,618,063 milliseconds ago.      The last packet sent successfully to the server was 44,734 milliseconds ago.
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(Unknown Source)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(Unknown Source)
at java.lang.reflect.Constructor.newInstance(Unknown Source)
at com.mysql.jdbc.Util.handleNewInstance(Util.java:411)
at com.mysql.jdbc.SQLError.createCommunicationsException(SQLError.java:1117)
at com.mysql.jdbc.MysqlIO.reuseAndReadPacket(MysqlIO.java:3567)
at com.mysql.jdbc.MysqlIO.reuseAndReadPacket(MysqlIO.java:3456)
at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:3997)
at com.mysql.jdbc.MysqlIO.sendCommand(MysqlIO.java:2468)
at com.mysql.jdbc.MysqlIO.sqlQueryDirect(MysqlIO.java:2629)
at com.mysql.jdbc.ConnectionImpl.execSQL(ConnectionImpl.java:2719)
at com.mysql.jdbc.PreparedStatement.executeInternal(PreparedStatement.java:2155)
at com.mysql.jdbc.PreparedStatement.execute(PreparedStatement.java:1379)
at com.jolbox.bonecp.PreparedStatementHandle.execute(PreparedStatementHandle.java:138)

我正在这样设置BoneCP：

BoneCPConfig config = new BoneCPConfig();
config.setJdbcUrl("jdbc:mysql://" + hostname + "/" + database);
config.setUsername(username); 
config.setPassword(password);
config.setMinConnectionsPerPartition(minPoolSize);
config.setMaxConnectionsPerPartition(maxPoolSize);
config.setIdleConnectionTestPeriodInMinutes(60);
config.setIdleMaxAgeInMinutes(240);
config.setPartitionCount(1);
connectionPool = new BoneCP(config);

我不确定如何确定mysql服务器的超时时间（默认值未更改），但是大约5或10分钟无连接池活动后出现此错误，似乎非常短。

Answer 1

您要么必须配置mysqls的空闲超时（设置wait_timeout = X / Interactive_timeout = X），要么可以配置连接池以发出keep-alive语句：

config.setIdleConnectionTestPeriodInMinutes(10);
config.setConnectionTestStatement("/* ping */ SELECT 1"):