请问关于TOMCAT的错误

请问关于TOMCAT的错误

WARNING: Reinitializing ServerSocket
Jul 26, 2007 5:31:13 PM org.apache.tomcat.util.net.PoolTcpEndpoint acceptSocket
SEVERE: Endpoint ServerSocket[addr=0.0.0.0/0.0.0.0,port=0,localport=80] ignored exception: java.net.SocketException: Too many open files
java.net.SocketException: Too many open files
        at java.net.PlainSocketImpl.socketAccept(Native Method)
        at java.net.PlainSocketImpl.accept(PlainSocketImpl.java:384)
        at java.net.ServerSocket.implAccept(ServerSocket.java:450)
        at java.net.ServerSocket.accept(ServerSocket.java:421)
        at org.apache.tomcat.util.net.DefaultServerSocketFactory.acceptSocket(DefaultServerSocketFactory.java:60)
        at org.apache.tomcat.util.net.PoolTcpEndpoint.acceptSocket(PoolTcpEndpoint.java:36
        at org.apache.tomcat.util.net.TcpWorkerThread.runIt(PoolTcpEndpoint.java:549)
        at org.apache.tomcat.util.threads.ThreadPool$ControlRunnable.run(ThreadPool.java:683)
        at java.lang.Thread.run(Thread.java:595)
请问有人知道是什么错误么?
java.net.SocketException: Too many open files

是不是开了文件没有关啊