I use Tomcat 3.2.3 and Struct in my project.When I write a test program to simulate concurrent requests,I got "Connection Refused Exception" in client.

Now the configration is:

Tomcat uses connection pool,max=50,max_spare=20,min_spare=5

My test program simulates 17 concurrent requests,I don't know why client receives "Connection Refused Exception",is there any other configration in Tomcat should be done ?