I run load test and get following error message, anybody could help me to fix it, (tomcat5.0.27, httpd2.0.52, pgpool3.0.2, postgresql7.4.6). 【 eption: Could not retrieve connection info from pool Caused by: org.apache.commons.dbcp.SQLNestedException: Could not retrieve connection info from pool at db.sqlmapdao.BaseSqlMapDao.executeQueryForObject(BaseSqlMapDao.java:98) at db.sqlmapdao.TsuhoMessageKakuninSqlMapDao.getEmcCommonMailSessionBySessionID(TsuhoMessageKakuninSqlMapDao.java:36) at sun.reflect.GeneratedMethodAccessor194.invoke(Unknown Source) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) at java.lang.reflect.Method.invoke(Method.java:324) at com.ibatis.dao.engine.impl.DaoProxy.invoke(DaoProxy.java:61) at $Proxy43.getEmcCommonMailSessionBySessionID(Unknown Source) at service.CommonService.getEmcCommonMailSessionBySessionID(CommonService.java:109) ... 39 more Caused by: org.apache.commons.dbcp.SQLNestedException: Could not retrieve connection info from pool at org.apache.commons.dbcp.datasources.SharedPoolDataSource.getPooledConnectionAndInfo(SharedPoolDataSource.java:169) at org.apache.commons.dbcp.datasources.InstanceKeyDataSource.getConnection(InstanceKeyDataSource.java:631) at org.apache.commons.dbcp.datasources.InstanceKeyDataSource.getConnection(InstanceKeyDataSource.java:615) at com.ibatis.sqlmap.engine.transaction.jdbc.JdbcTransaction.init(JdbcTransaction.java:48) at com.ibatis.sqlmap.engine.transaction.jdbc.JdbcTransaction.getConnection(JdbcTransaction.java:89) at com.ibatis.sqlmap.engine.mapping.statement.GeneralStatement.executeQueryForObject(GeneralStatement.java:99) at com.ibatis.sqlmap.engine.impl.SqlMapExecutorDelegate.queryForObject(SqlMapExecutorDelegate.java:561) at com.ibatis.sqlmap.engine.impl.SqlMapExecutorDelegate.queryForObject(SqlMapExecutorDelegate.java:536) at com.ibatis.sqlmap.engine.impl.SqlMapSessionImpl.queryForObject(SqlMapSessionImpl.java:97) at com.ibatis.sqlmap.engine.impl.SqlMapClientImpl.queryForObject(SqlMapClientImpl.java:69) at db.sqlmapdao.BaseSqlMapDao.executeQueryForObject(BaseSqlMapDao.java:96) ... 46 more Caused by: java.lang.NullPointerException at org.apache.commons.collections.SequencedHashMap.removeEntry(SequencedHashMap.java:215) at org.apache.commons.collections.SequencedHashMap.put(SequencedHashMap.java:433) at org.apache.commons.collections.LRUMap.put(LRUMap.java:125) at org.apache.commons.dbcp.datasources.SharedPoolDataSource.getUserPassKey(SharedPoolDataSource.java:179) at org.apache.commons.dbcp.datasources.SharedPoolDataSource.getPooledConnectionAndInfo(SharedPoolDataSource.java:165) ... 56 more 】