每天晚上到凌晨时，总是报MYSQL链接池错误，请问有谁知道是什么原因啊？
2007-07-22   00:05:07,631   [org.logicalcobwebs.proxool.survey]-[ERROR]   Prototype  
（每天晚上到这个点时，总是报这个错误，请问有谁知道是什么原因啊？  
MYSQL：5.0.17版本，  
驱动：mysql-connector-java-3.1.10-bin.jar）  
com.mysql.jdbc.CommunicationsException:   Communications   link   failure   due   to   underlying   exception:  

**   BEGIN   NESTED   EXCEPTION   **  

java.net.SocketException  
MESSAGE:   java.net.ConnectException:   Connection   refused

STACKTRACE:

java.net.SocketException:   java.net.ConnectException:   Connection   refused  
at   com.mysql.jdbc.StandardSocketFactory.connect(StandardSocketFactory.java:156)  
at   com.mysql.jdbc.MysqlIO. <init> (MysqlIO.java:283)  
at   com.mysql.jdbc.Connection.createNewIO(Connection.java:2541)  
at   com.mysql.jdbc.Connection. <init> (Connection.java:1474)  
at   com.mysql.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:264)  
at   java.sql.DriverManager.getConnection(DriverManager.java:512)  
at   java.sql.DriverManager.getConnection(DriverManager.java:140)  
at   org.logicalcobwebs.proxool.DefaultConnectionBuilder.buildConnection(DefaultConnectionBuilder.java:39)  
at   org.logicalcobwebs.proxool.Prototyper.buildConnection(Prototyper.java:159)  
at   org.logicalcobwebs.proxool.Prototyper.sweep(Prototyper.java:102)  
at   org.logicalcobwebs.proxool.PrototyperThread.run(PrototyperThread.java:44)

**   END   NESTED   EXCEPTION   **

Last   packet   sent   to   the   server   was   0   ms   ago.  
at   com.mysql.jdbc.Connection.createNewIO(Connection.java:2607)  
at   com.mysql.jdbc.Connection. <init> (Connection.java:1474)  
at   com.mysql.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:264)  
at   java.sql.DriverManager.getConnection(DriverManager.java:512)  
at   java.sql.DriverManager.getConnection(DriverManager.java:140)  
at   org.logicalcobwebs.proxool.DefaultConnectionBuilder.buildConnection(DefaultConnectionBuilder.java:39)  
at   org.logicalcobwebs.proxool.Prototyper.buildConnection(Prototyper.java:159)  
at   org.logicalcobwebs.proxool.Prototyper.sweep(Prototyper.java:102)  
at   org.logicalcobwebs.proxool.PrototyperThread.run(PrototyperThread.java:44)  
2007-07-22   00:05:07,641   [org.logicalcobwebs.proxool.survey]-[ERROR]   Prototype  
com.mysql.jdbc.CommunicationsException:   Communications   link   failure   due   to   underlying   exception:  

**   BEGIN   NESTED   EXCEPTION   **  

java.net.SocketException  
MESSAGE:   java.net.ConnectException:   Connection   refused

STACKTRACE:

java.net.SocketExcep