c3p0出現 An attempt by a client to checkout a Connection has timed out，

c3p0出現 An attempt by a client to checkout a Connection has timed out，

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)

Caused by: com.mchange.v2.resourcepool.TimeoutException: A client timed out while waiting to acquire a resource from com.mchange.v2.resourcepool.BasicResourcePool@a0e5175 -- 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.prelimCheckoutResource(BasicResourcePool.java:590)at com.mchange.v2.resourcepool.BasicResourcePool.prelimCheckoutResource(BasicResourcePool.java:590)at com.mchange.v2.resourcepool.BasicResourcePool.prelimCheckoutResource(BasicResourcePool.java:590)at com.mchange.v2.resourcepool.BasicResourcePool.prelimCheckoutResource(BasicResourcePool.java:590)at com.mchange.v2.resourcepool.BasicResourcePool.prelimCheckoutResource(BasicResourcePool.java:590)at com.mchange.v2.resourcepool.BasicResourcePool.prelimCheckoutResource(BasicResourcePool.java:590)at com.mchange.v2.resourcepool.BasicResourcePool.prelimCheckoutResource(BasicResourcePool.java:590)at com.mchange.v2.resourcepool.BasicResourcePool.checkoutResource(BasicResourcePool.java:477)at com.mchange.v2.c3p0.impl.C3P0PooledConnectionPool.checkoutPooledConnection(C3P0PooledConnectionPool.java:525)... 7 more

解決方案：緩衝關閉也就是把c3p0.max_statements 設定成0（如果不設定為0，可能造成connection不能真正被關閉），這樣就不會有緩衝的preparedstatement，而設定的c3p0.idle_test_period又小於c3p0.timeout，這樣的設定應該解決問題了。