Help, Tomcat 4.1.31 no response

[chao zhang <to...@yahoo.com.cn>]

My Operating System: RedHat 9
JVM version: j2sdk 1.4.2_09
Tomcat: tomcat 4.1.31
Hardware configuration: Dual PIII 1G, 512MB memory
users: about 30
   
  I have a web application and have deployed to my tomcat 4.1.31. The problem is: tomcat will no response after running about 1 week. When i enter the URL in IE and press enter, there is nothing happen except the progress-bar of IE is increasing, after about 2 minutes, IE displayed "Cannot display this page". The tomcat's process in server(process named "java") has no any exception, the memory usage and cpu usage is normal.
   
  I think that maybe tomcat had no idle thread in thread pool to serve for requests so, it kept waiting for an thread available. If this is true, my web application must have bugs which exhausted the thread and resources. But i don't know, in what situation, these threads cannot be callback by tomcat. My database resultsets, statements and connections are released(MySQL database, version 3.23.58, used tomcat's dbcp connection pool), my network sockets instance are closed and any no-use class instances have been set to null.
   
  There is another important issue: when tomcat had no response, the only thing I can do is to restart the tomcat server but, when i invoked the tomcat's "shutdown.sh" script, I found that the 8080 port was not listening but the "java" process was still alive. I must use "kill -9 <the java process's pid>" to kill the process.
    
  my web application is based on struts framework. When a request arrives, a Action Servlet is invoked then, servlet will invoke my singleton mode logic class, logical classes will fill lots of entity classes and return them back to the client. Did these singleton-mode logical class cause the problem?
   
  My English is poor and I hope everybody can read me. Any help and suggestion will be appreciated. Thanks.

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