简单介绍tomcat中maxThreads，acceptCount，connectionTimeout

<?xml version='1.0' encoding='utf-8'?>
<Server port="8005" shutdown="SHUTDOWN">
  <Listener className="org.apache.catalina.startup.VersionLoggerListener" />
  <Listener className="org.apache.catalina.core.AprLifecycleListener" SSLEngine="on" />
  <!--Initialize Jasper prior to webapps are loaded. Documentation at /docs/jasper-howto.html -->
  <Listener className="org.apache.catalina.core.JasperListener" />
  <!-- Prevent memory leaks due to use of particular java/javax APIs-->
  <Listener className="org.apache.catalina.core.JreMemoryLeakPreventionListener" />
  <Listener className="org.apache.catalina.mbeans.GlobalResourcesLifecycleListener" />
  <Listener className="org.apache.catalina.core.ThreadLocalLeakPreventionListener" />

  <GlobalNamingResources>
    <Resource name="UserDatabase" auth="Container"
              type="org.apache.catalina.UserDatabase"
              description="User database that can be updated and saved"
              factory="org.apache.catalina.users.MemoryUserDatabaseFactory"
              pathname="conf/tomcat-users.xml" />
  </GlobalNamingResources>


	<Service name="Catalina">
	<!--
    <Connector port="8080" protocol="HTTP/1.1"   connectionTimeout="20000"   redirectPort="8443" />-->

    <!-- Define an AJP 1.3 Connector on port 8080 -->
	<!-- maxThreads 请求处理线程的最大数量。默认值是200（Tomcat7和8都是的）。
	如果该Connector绑定了Executor，这个值会被忽略，因为该Connector将使用绑定的Executor，而不是内置的线程池来执行任务-->
	
	<!-- acceptCount accept队列的长度；当accept队列中连接的个数达到acceptCount时，队列满，进来的请求一律被拒绝。默认值是100-->
	
	<!-- connectionTimeout Tomcat在任意时刻接收和处理的最大连接数。当Tomcat接收的连接数达到maxConnections时，
	Acceptor线程不会读取accept队列中的连接；这时accept队列中的线程会一直阻塞着，
	直到Tomcat接收的连接数小于maxConnections。如果设置为-1，则连接数不受限制。-->
    <Connector port="8009" protocol="AJP/1.3" redirectPort="8443" maxThreads="600" minSpareThreads="100" maxSpareThreads="500" acceptCount="700" connectionTimeout="20000"/>


    <Engine name="Catalina" defaultHost="localhost">


      <Realm className="org.apache.catalina.realm.LockOutRealm">
      <Realm className="org.apache.catalina.realm.UserDatabaseRealm" resourceName="UserDatabase"/>
      </Realm>

      <Host name="localhost"  appBase="webapps" unpackWARs="true" autoDeploy="true">

        <Valve className="org.apache.catalina.valves.AccessLogValve" directory="logs"
               prefix="localhost_access_log." suffix=".txt"
               pattern="%h %l %u %t "%r" %s %b" />

      </Host>
    </Engine>
  </Service>
</Server>