An attempt by a client to checkout a Connection has timed out.

Caused by: java.sql.SQLException: An attempt by a client to checkout a Connection has timed out.

at com.mchange.v2.sql.SqlUtils.toSQLException(SqlUtils.java:106)

at com.mchange.v2.sql.SqlUtils.toSQLException(SqlUtils.java:65)

at com.mchange.v2.c3p0.impl.C3P0PooledConnectionPool.checkoutPooledConnection(C3P0PooledConnectionPool.java:527)

at com.mchange.v2.c3p0.impl.AbstractPoolBackedDataSource.getConnection(AbstractPoolBackedDataSource.java:128)

at org.springframework.jdbc.datasource.DataSourceUtils.doGetConnection(DataSourceUtils.java:113)

at org.springframework.jdbc.datasource.DataSourceUtils.getConnection(DataSourceUtils.java:79)

… 5 more

Caused by: com.mchange.v2.resourcepool.TimeoutException: A client timed out while waiting to acquire a resource from com.mchange.v2.resourcepool.BasicResourcePool@2020851 – timeout at awaitAvailable()

at com.mchange.v2.resourcepool.BasicResourcePool.awaitAvailable(BasicResourcePool.java:1317)

at com.mchange.v2.resourcepool.BasicResourcePool.prelimCheckoutResource(BasicResourcePool.java:557)

at com.mchange.v2.resourcepool.BasicResourcePool.checkoutResource(BasicResourcePool.java:477)

at com.mchange.v2.c3p0.impl.C3P0PooledConnectionPool.checkoutPooledConnection(C3P0PooledConnectionPool.java:525)

… 8 more

使用c3p0链接池的时候报的错误，查了查说是并发数过大的时候会发生，解决办法是更改配置文件里的property name=”acquireIncrement” value=”5” ，当链接耗尽时c3p0一次性获取的连接数目。如果没配置，默认是3