I tried difference setting in Jmeter and Tomcat.

If the Threads number in JMeter is 1~200, Then tomcat is okay.

If It is 300, Then after serving few requests, tomcat starts to output errors.

Here is the error show in JMeter

java.net.ConnectException: Connection refused: connect
at java.net.PlainSocketImpl.socketConnect(Native Method)
at java.net.PlainSocketImpl.doConnect(Unknown Source)
at java.net.PlainSocketImpl.connectToAddress(Unknown Source)
at java.net.PlainSocketImpl.connect(Unknown Source)
at java.net.SocksSocketImpl.connect(Unknown Source)
at java.net.Socket.connect(Unknown Source)
at java.net.Socket.connect(Unknown Source)
at sun.net.NetworkClient.doConnect(Unknown Source)
at sun.net.www.http.HttpClient.openServer(Unknown Source)
at sun.net.www.http.HttpClient.openServer(Unknown Source)
at sun.net.www.http.HttpClient.<init>(Unknown Source)
at sun.net.www.http.HttpClient.New(Unknown Source)
at sun.net.www.http.HttpClient.New(Unknown Source)
at sun.net.www.protocol.http.HttpURLConnection.getNewHttpClient(Unknown Source)
at sun.net.www.protocol.http.HttpURLConnection.plainConnect(Unknown Source)
at sun.net.www.protocol.http.HttpURLConnection.connect(Unknown Source)
at org.apache.jmeter.protocol.http.sampler.HTTPJavaImpl.sample(HTTPJavaImpl.java:483)
at org.apache.jmeter.protocol.http.sampler.HTTPSamplerProxy.sample(HTTPSamplerProxy.java:62)
at org.apache.jmeter.protocol.http.sampler.HTTPSamplerBase.sample(HTTPSamplerBase.java:1018)
at org.apache.jmeter.protocol.http.sampler.HTTPSamplerBase.sample(HTTPSamplerBase.java:1004)
at org.apache.jmeter.threads.JMeterThread.process_sampler(JMeterThread.java:411)
at org.apache.jmeter.threads.JMeterThread.run(JMeterThread.java:297)
at java.lang.Thread.run(Unknown Source)

My tomcat server.xml in eclipse

<!--The connectors can use a shared executor, you can define one or more named thread pools-->
<Executor name="tomcatThreadPool" namePrefix="catalina-exec-" 
    maxThreads="2000" minSpareThreads="250"
    acceptCount="2000"/>

<Connector executor="tomcatThreadPool" URIEncoding="UTF-8" connectionTimeout="20000" port="8080" protocol="HTTP/1.1" redirectPort="8443" />

Any idea why this is happening ? How do i check the server.xml is correctly used?

It is a JSF2 application if it helps.

Thanks in advance.