Tomcat Architecture Series-3.Mastering Tomcat Connector

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Mastering Tomcat Connector: HTTP, AJP and NIO Implementation

Introduction

Tomcat Connectors are crucial components that handle all communication between clients and the servlet containers. This article deep dives into different types of connectors, their implementations, and how to optimize them for production use.

Table of Contents

  1. Connector Architecture Overview
  2. Http Connector Deep Dive
  3. AJP Connector Analysis
  4. NIO Connector Implementation
  5. Performance Optimization
  6. Advanced Configuration
  7. Troubleshooting Guide

1. Connector Architecture Overview

1.1 Basic Connector Structure 

<span>public</span> <span>interface</span> <span>Connector</span> <span>{</span>
  <span>// Core connector methods</span>
  <span>public</span> <span>void</span> <span>setService</span><span>(</span><span>Service</span> <span>service</span><span>);</span>
  <span>public</span> <span>Service</span> <span>getService</span><span>();</span>
  <span>public</span> <span>void</span> <span>init</span><span>()</span> <span>throws</span> <span>LifecycleException</span><span>;</span>
  <span>public</span> <span>void</span> <span>start</span><span>()</span> <span>throws</span> <span>LifecycleException</span><span>;</span>
  <span>public</span> <span>void</span> <span>stop</span><span>()</span> <span>throws</span> <span>LifecycleException</span><span>;</span>
  <span>// Protocol configuration</span>
  <span>public</span> <span>void</span> <span>setProtocol</span><span>(</span><span>String</span> <span>protocol</span><span>);</span>
  <span>public</span> <span>String</span> <span>getProtocol</span><span>();</span>
  <span>// Port configuration</span>
  <span>public</span> <span>void</span> <span>setPort</span><span>(</span><span>int</span> <span>port</span><span>);</span>
  <span>public</span> <span>int</span> <span>getPort</span><span>();</span>
<span>}</span>
<span>public</span> <span>interface</span> <span>Connector</span> <span>{</span>
  <span>// Core connector methods</span>
  <span>public</span> <span>void</span> <span>setService</span><span>(</span><span>Service</span> <span>service</span><span>);</span>
  <span>public</span> <span>Service</span> <span>getService</span><span>();</span>
  <span>public</span> <span>void</span> <span>init</span><span>()</span> <span>throws</span> <span>LifecycleException</span><span>;</span>
  <span>public</span> <span>void</span> <span>start</span><span>()</span> <span>throws</span> <span>LifecycleException</span><span>;</span>
  <span>public</span> <span>void</span> <span>stop</span><span>()</span> <span>throws</span> <span>LifecycleException</span><span>;</span>

  <span>// Protocol configuration</span>
  <span>public</span> <span>void</span> <span>setProtocol</span><span>(</span><span>String</span> <span>protocol</span><span>);</span>
  <span>public</span> <span>String</span> <span>getProtocol</span><span>();</span>

  <span>// Port configuration</span>
  <span>public</span> <span>void</span> <span>setPort</span><span>(</span><span>int</span> <span>port</span><span>);</span>
  <span>public</span> <span>int</span> <span>getPort</span><span>();</span>
<span>}</span>
public interface Connector {
  // Core connector methods
  public void setService(Service service);
  public Service getService();
  public void init() throws LifecycleException;
  public void start() throws LifecycleException;
  public void stop() throws LifecycleException;

  // Protocol configuration
  public void setProtocol(String protocol);
  public String getProtocol();

  // Port configuration
  public void setPort(int port);
  public int getPort();
}

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1.2 Connector Pipline 

<span>public</span> <span>class</span> <span>ConnectorPipeline</span> <span>{</span>
  <span>private</span> <span>final</span> <span>List</span><span><</span><span>Valve</span><span>></span> <span>valves</span> <span>=</span> <span>new</span> <span>ArrayList</span><span><>();</span>
  <span>private</span> <span>Valve</span> <span>basic</span> <span>=</span> <span>null</span><span>;</span>
  <span>public</span> <span>void</span> <span>addValve</span><span>(</span><span>Valve</span> <span>valve</span><span>)</span> <span>{</span>
    <span>valves</span><span>.</span><span>add</span><span>(</span><span>valve</span><span>);</span>
  <span>}</span>
  <span>public</span> <span>void</span> <span>invoke</span><span>(</span><span>Request</span> <span>request</span><span>,</span> <span>Response</span> <span>response</span><span>)</span> <span>{</span>
    <span>// Process through valve chain</span>
    <span>for</span> <span>(</span><span>Valve</span> <span>valve</span> <span>:</span> <span>valves</span><span>)</span> <span>{</span>
      <span>valve</span><span>.</span><span>invoke</span><span>(</span><span>request</span><span>,</span> <span>response</span><span>);</span>
    <span>}</span>
    <span>// Finally invoke basic valve</span>
    <span>if</span> <span>(</span><span>basic</span> <span>!=</span> <span>null</span><span>)</span> <span>{</span>
      <span>basic</span><span>.</span><span>invoke</span><span>(</span><span>request</span><span>,</span> <span>response</span><span>);</span>
    <span>}</span>
  <span>}</span>
<span>}</span>
<span>public</span> <span>class</span> <span>ConnectorPipeline</span> <span>{</span>
  <span>private</span> <span>final</span> <span>List</span><span><</span><span>Valve</span><span>></span> <span>valves</span> <span>=</span> <span>new</span> <span>ArrayList</span><span><>();</span>
  <span>private</span> <span>Valve</span> <span>basic</span> <span>=</span> <span>null</span><span>;</span>

  <span>public</span> <span>void</span> <span>addValve</span><span>(</span><span>Valve</span> <span>valve</span><span>)</span> <span>{</span>
    <span>valves</span><span>.</span><span>add</span><span>(</span><span>valve</span><span>);</span>
  <span>}</span>

  <span>public</span> <span>void</span> <span>invoke</span><span>(</span><span>Request</span> <span>request</span><span>,</span> <span>Response</span> <span>response</span><span>)</span> <span>{</span>
    <span>// Process through valve chain</span>
    <span>for</span> <span>(</span><span>Valve</span> <span>valve</span> <span>:</span> <span>valves</span><span>)</span> <span>{</span>
      <span>valve</span><span>.</span><span>invoke</span><span>(</span><span>request</span><span>,</span> <span>response</span><span>);</span>
    <span>}</span>
    <span>// Finally invoke basic valve</span>
    <span>if</span> <span>(</span><span>basic</span> <span>!=</span> <span>null</span><span>)</span> <span>{</span>
      <span>basic</span><span>.</span><span>invoke</span><span>(</span><span>request</span><span>,</span> <span>response</span><span>);</span>
    <span>}</span>
  <span>}</span>
<span>}</span>
public class ConnectorPipeline {
  private final List<Valve> valves = new ArrayList<>();
  private Valve basic = null;

  public void addValve(Valve valve) {
    valves.add(valve);
  }

  public void invoke(Request request, Response response) {
    // Process through valve chain
    for (Valve valve : valves) {
      valve.invoke(request, response);
    }
    // Finally invoke basic valve
    if (basic != null) {
      basic.invoke(request, response);
    }
  }
}

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2.HTTP Connector Deep Dive

HTTP/1.1 Protocol Implementation 

<span>public</span> <span>class</span> <span>Http11Protocol</span> <span>extends</span> <span>AbstractHttp11Protocol</span><span><</span><span>NioChannel</span><span>></span> <span>{</span>
  <span>@Override</span>
  <span>protected</span> <span>void</span> <span>initializeConnectionLatch</span><span>()</span> <span>{</span>
    <span>// Initialize connection count</span>
    <span>connectionLatch</span> <span>=</span> <span>new</span> <span>CountDownLatch</span><span>(</span><span>1</span><span>);</span>
  <span>}</span>
  <span>@Override</span>
  <span>protected</span> <span>Processor</span> <span>createProcessor</span><span>()</span> <span>{</span>
    <span>// Create HTTP processor</span>
    <span>Http11Processor</span> <span>processor</span> <span>=</span> <span>new</span> <span>Http11Processor</span><span>(</span>
      <span>getMaxHttpHeaderSize</span><span>(),</span>
      <span>getEndpoint</span><span>(),</span>
      <span>getMaxTrailerSize</span><span>(),</span>
      <span>allowedTrailerHeaders</span><span>,</span>
      <span>getMaxExtensionSize</span><span>(),</span>
      <span>getMaxSwallowSize</span><span>(),</span>
      <span>getHttp11Protocol</span><span>().</span><span>getRelaxedPathChars</span><span>(),</span>
      <span>getHttp11Protocol</span><span>().</span><span>getRelaxedQueryChars</span><span>());</span>
    <span>processor</span><span>.</span><span>setAdapter</span><span>(</span><span>getAdapter</span><span>());</span>
    <span>return</span> <span>processor</span><span>;</span>
  <span>}</span>
<span>}</span>
<span>public</span> <span>class</span> <span>Http11Protocol</span> <span>extends</span> <span>AbstractHttp11Protocol</span><span><</span><span>NioChannel</span><span>></span> <span>{</span>

  <span>@Override</span>
  <span>protected</span> <span>void</span> <span>initializeConnectionLatch</span><span>()</span> <span>{</span>
    <span>// Initialize connection count</span>
    <span>connectionLatch</span> <span>=</span> <span>new</span> <span>CountDownLatch</span><span>(</span><span>1</span><span>);</span>
  <span>}</span>

  <span>@Override</span>
  <span>protected</span> <span>Processor</span> <span>createProcessor</span><span>()</span> <span>{</span>
    <span>// Create HTTP processor</span>
    <span>Http11Processor</span> <span>processor</span> <span>=</span> <span>new</span> <span>Http11Processor</span><span>(</span>
      <span>getMaxHttpHeaderSize</span><span>(),</span>
      <span>getEndpoint</span><span>(),</span>
      <span>getMaxTrailerSize</span><span>(),</span>
      <span>allowedTrailerHeaders</span><span>,</span>
      <span>getMaxExtensionSize</span><span>(),</span>
      <span>getMaxSwallowSize</span><span>(),</span>
      <span>getHttp11Protocol</span><span>().</span><span>getRelaxedPathChars</span><span>(),</span>
      <span>getHttp11Protocol</span><span>().</span><span>getRelaxedQueryChars</span><span>());</span>
    <span>processor</span><span>.</span><span>setAdapter</span><span>(</span><span>getAdapter</span><span>());</span>
    <span>return</span> <span>processor</span><span>;</span>
  <span>}</span>
<span>}</span>
public class Http11Protocol extends AbstractHttp11Protocol<NioChannel> {

  @Override
  protected void initializeConnectionLatch() {
    // Initialize connection count
    connectionLatch = new CountDownLatch(1);
  }

  @Override
  protected Processor createProcessor() {
    // Create HTTP processor
    Http11Processor processor = new Http11Processor(
      getMaxHttpHeaderSize(),
      getEndpoint(),
      getMaxTrailerSize(),
      allowedTrailerHeaders,
      getMaxExtensionSize(),
      getMaxSwallowSize(),
      getHttp11Protocol().getRelaxedPathChars(),
      getHttp11Protocol().getRelaxedQueryChars());
    processor.setAdapter(getAdapter());
    return processor;
  }
}

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2.2 HTTP Request Processing 

<span>public</span> <span>class</span> <span>Http11Processor</span> <span>implements</span> <span>ActionHook</span><span>,</span> <span>Processor</span> <span>{</span>
  <span>@Override</span>
  <span>public</span> <span>SocketState</span> <span>process</span><span>(</span><span>SocketWrapperBase</span><span><?></span> <span>socketWrapper</span><span>)</span>
    <span>throws</span> <span>IOException</span> <span>{</span>
    <span>// Initialize request and response</span>
    <span>Request</span> <span>req</span> <span>=</span> <span>new</span> <span>Request</span><span>();</span>
    <span>Response</span> <span>res</span> <span>=</span> <span>new</span> <span>Response</span><span>();</span>
    <span>// Parse HTTP request</span>
    <span>parseRequest</span><span>(</span><span>socketWrapper</span><span>,</span> <span>req</span><span>);</span>
    <span>// Process request</span>
    <span>getAdapter</span><span>().</span><span>service</span><span>(</span><span>req</span><span>,</span> <span>res</span><span>);</span>
    <span>// Send response</span>
    <span>sendResponse</span><span>(</span><span>res</span><span>);</span>
    <span>return</span> <span>SocketState</span><span>.</span><span>CLOSED</span><span>;</span>
  <span>}</span>
<span>}</span>
<span>public</span> <span>class</span> <span>Http11Processor</span> <span>implements</span> <span>ActionHook</span><span>,</span> <span>Processor</span> <span>{</span>

  <span>@Override</span>
  <span>public</span> <span>SocketState</span> <span>process</span><span>(</span><span>SocketWrapperBase</span><span><?></span> <span>socketWrapper</span><span>)</span>
    <span>throws</span> <span>IOException</span> <span>{</span>
    <span>// Initialize request and response</span>
    <span>Request</span> <span>req</span> <span>=</span> <span>new</span> <span>Request</span><span>();</span>
    <span>Response</span> <span>res</span> <span>=</span> <span>new</span> <span>Response</span><span>();</span>

    <span>// Parse HTTP request</span>
    <span>parseRequest</span><span>(</span><span>socketWrapper</span><span>,</span> <span>req</span><span>);</span>

    <span>// Process request</span>
    <span>getAdapter</span><span>().</span><span>service</span><span>(</span><span>req</span><span>,</span> <span>res</span><span>);</span>

    <span>// Send response</span>
    <span>sendResponse</span><span>(</span><span>res</span><span>);</span>

    <span>return</span> <span>SocketState</span><span>.</span><span>CLOSED</span><span>;</span>
  <span>}</span>
<span>}</span>
public class Http11Processor implements ActionHook, Processor {

  @Override
  public SocketState process(SocketWrapperBase<?> socketWrapper)
    throws IOException {
    // Initialize request and response
    Request req = new Request();
    Response res = new Response();

    // Parse HTTP request
    parseRequest(socketWrapper, req);

    // Process request
    getAdapter().service(req, res);

    // Send response
    sendResponse(res);

    return SocketState.CLOSED;
  }
}

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3. AJP Connector Analysis

3.1 AJP Protocol Implementation 

<span>public</span> <span>class</span> <span>AjpProtocol</span> <span>extends</span> <span>AbstractAjpProtocol</span><span><</span><span>NioChannel</span><span>></span> <span>{</span>
  <span>@Override</span>
  <span>protected</span> <span>Processor</span> <span>createProcessor</span><span>()</span> <span>{</span>
    <span>AjpProcessor</span> <span>processor</span> <span>=</span> <span>new</span> <span>AjpProcessor</span><span>(</span><span>getPacketSize</span><span>(),</span> <span>getEndpoint</span><span>());</span>
    <span>processor</span><span>.</span><span>setAdapter</span><span>(</span><span>getAdapter</span><span>());</span>
    <span>return</span> <span>processor</span><span>;</span>
  <span>}</span>
  <span>@Override</span>
  <span>protected</span> <span>void</span> <span>initializeConnectionLatch</span><span>()</span> <span>{</span>
    <span>connectionLatch</span> <span>=</span> <span>new</span> <span>CountDownLatch</span><span>(</span><span>1</span><span>);</span>
  <span>}</span>
<span>}</span>
<span>public</span> <span>class</span> <span>AjpProtocol</span> <span>extends</span> <span>AbstractAjpProtocol</span><span><</span><span>NioChannel</span><span>></span> <span>{</span>

  <span>@Override</span>
  <span>protected</span> <span>Processor</span> <span>createProcessor</span><span>()</span> <span>{</span>
    <span>AjpProcessor</span> <span>processor</span> <span>=</span> <span>new</span> <span>AjpProcessor</span><span>(</span><span>getPacketSize</span><span>(),</span> <span>getEndpoint</span><span>());</span>
    <span>processor</span><span>.</span><span>setAdapter</span><span>(</span><span>getAdapter</span><span>());</span>
    <span>return</span> <span>processor</span><span>;</span>
  <span>}</span>

  <span>@Override</span>
  <span>protected</span> <span>void</span> <span>initializeConnectionLatch</span><span>()</span> <span>{</span>
    <span>connectionLatch</span> <span>=</span> <span>new</span> <span>CountDownLatch</span><span>(</span><span>1</span><span>);</span>
  <span>}</span>
<span>}</span>
public class AjpProtocol extends AbstractAjpProtocol<NioChannel> {

  @Override
  protected Processor createProcessor() {
    AjpProcessor processor = new AjpProcessor(getPacketSize(), getEndpoint());
    processor.setAdapter(getAdapter());
    return processor;
  }

  @Override
  protected void initializeConnectionLatch() {
    connectionLatch = new CountDownLatch(1);
  }
}

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3.2 AJP Message Structure 

<span>public</span> <span>class</span> <span>AjpMessage</span> <span>{</span>
    <span>private</span> <span>final</span> <span>byte</span><span>[]</span> <span>buf</span><span>;</span>
    <span>private</span> <span>int</span> <span>pos</span><span>;</span>
    <span>public</span> <span>void</span> <span>reset</span><span>()</span> <span>{</span>
        <span>pos</span> <span>=</span> <span>0</span><span>;</span>
    <span>}</span>
    <span>public</span> <span>void</span> <span>appendByte</span><span>(</span><span>int</span> <span>val</span><span>)</span> <span>{</span>
        <span>buf</span><span>[</span><span>pos</span><span>++]</span> <span>=</span> <span>(</span><span>byte</span><span>)</span> <span>val</span><span>;</span>
    <span>}</span>
    <span>public</span> <span>void</span> <span>appendInt</span><span>(</span><span>int</span> <span>val</span><span>)</span> <span>{</span>
        <span>buf</span><span>[</span><span>pos</span><span>++]</span> <span>=</span> <span>(</span><span>byte</span><span>)</span> <span>((</span><span>val</span> <span>>>></span> <span>8</span><span>)</span> <span>&</span> <span>0xFF</span><span>);</span>
        <span>buf</span><span>[</span><span>pos</span><span>++]</span> <span>=</span> <span>(</span><span>byte</span><span>)</span> <span>(</span><span>val</span> <span>&</span> <span>0xFF</span><span>);</span>
    <span>}</span>
<span>}</span>
<span>public</span> <span>class</span> <span>AjpMessage</span> <span>{</span>
    <span>private</span> <span>final</span> <span>byte</span><span>[]</span> <span>buf</span><span>;</span>
    <span>private</span> <span>int</span> <span>pos</span><span>;</span>

    <span>public</span> <span>void</span> <span>reset</span><span>()</span> <span>{</span>
        <span>pos</span> <span>=</span> <span>0</span><span>;</span>
    <span>}</span>

    <span>public</span> <span>void</span> <span>appendByte</span><span>(</span><span>int</span> <span>val</span><span>)</span> <span>{</span>
        <span>buf</span><span>[</span><span>pos</span><span>++]</span> <span>=</span> <span>(</span><span>byte</span><span>)</span> <span>val</span><span>;</span>
    <span>}</span>

    <span>public</span> <span>void</span> <span>appendInt</span><span>(</span><span>int</span> <span>val</span><span>)</span> <span>{</span>
        <span>buf</span><span>[</span><span>pos</span><span>++]</span> <span>=</span> <span>(</span><span>byte</span><span>)</span> <span>((</span><span>val</span> <span>>>></span> <span>8</span><span>)</span> <span>&</span> <span>0xFF</span><span>);</span>
        <span>buf</span><span>[</span><span>pos</span><span>++]</span> <span>=</span> <span>(</span><span>byte</span><span>)</span> <span>(</span><span>val</span> <span>&</span> <span>0xFF</span><span>);</span>
    <span>}</span>
<span>}</span>
public class AjpMessage {
    private final byte[] buf;
    private int pos;

    public void reset() {
        pos = 0;
    }

    public void appendByte(int val) {
        buf[pos++] = (byte) val;
    }

    public void appendInt(int val) {
        buf[pos++] = (byte) ((val >>> 8) & 0xFF);
        buf[pos++] = (byte) (val & 0xFF);
    }
}

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4. NIO Connector Implementation

4.1 NIO Endpoint 

<span>public</span> <span>class</span> <span>NioEndpoint</span> <span>extends</span> <span>AbstractJsseEndpoint</span><span><</span><span>NioChannel</span><span>,</span><span>SocketChannel</span><span>></span> <span>{</span>
    <span>private</span> <span>Poller</span><span>[]</span> <span>pollers</span><span>;</span>
    <span>private</span> <span>NioSelectorPool</span> <span>selectorPool</span><span>;</span>
    <span>@Override</span>
    <span>protected</span> <span>void</span> <span>startInternal</span><span>()</span> <span>throws</span> <span>Exception</span> <span>{</span>
        <span>// Initialize NIO components</span>
        <span>if</span> <span>(!</span><span>running</span><span>)</span> <span>{</span>
            <span>running</span> <span>=</span> <span>true</span><span>;</span>
            <span>paused</span> <span>=</span> <span>false</span><span>;</span>
            <span>// Create worker collection</span>
            <span>processorCache</span> <span>=</span> <span>new</span> <span>SynchronizedStack</span><span><>(</span>
                    <span>SynchronizedStack</span><span>.</span><span>DEFAULT_SIZE</span><span>,</span>
                    <span>socketProperties</span><span>.</span><span>getProcessorCache</span><span>());</span>
            <span>// Start poller threads</span>
            <span>pollers</span> <span>=</span> <span>new</span> <span>Poller</span><span>[</span><span>getPollerThreadCount</span><span>()];</span>
            <span>for</span> <span>(</span><span>int</span> <span>i</span> <span>=</span> <span>0</span><span>;</span> <span>i</span> <span><</span> <span>pollers</span><span>.</span><span>length</span><span>;</span> <span>i</span><span>++)</span> <span>{</span>
                <span>pollers</span><span>[</span><span>i</span><span>]</span> <span>=</span> <span>new</span> <span>Poller</span><span>();</span>
                <span>Thread</span> <span>pollerThread</span> <span>=</span> <span>new</span> <span>Thread</span><span>(</span><span>pollers</span><span>[</span><span>i</span><span>]);</span>
                <span>pollerThread</span><span>.</span><span>start</span><span>();</span>
            <span>}</span>
        <span>}</span>
    <span>}</span>
<span>}</span>
<span>public</span> <span>class</span> <span>NioEndpoint</span> <span>extends</span> <span>AbstractJsseEndpoint</span><span><</span><span>NioChannel</span><span>,</span><span>SocketChannel</span><span>></span> <span>{</span>

    <span>private</span> <span>Poller</span><span>[]</span> <span>pollers</span><span>;</span>
    <span>private</span> <span>NioSelectorPool</span> <span>selectorPool</span><span>;</span>

    <span>@Override</span>
    <span>protected</span> <span>void</span> <span>startInternal</span><span>()</span> <span>throws</span> <span>Exception</span> <span>{</span>
        <span>// Initialize NIO components</span>
        <span>if</span> <span>(!</span><span>running</span><span>)</span> <span>{</span>
            <span>running</span> <span>=</span> <span>true</span><span>;</span>
            <span>paused</span> <span>=</span> <span>false</span><span>;</span>

            <span>// Create worker collection</span>
            <span>processorCache</span> <span>=</span> <span>new</span> <span>SynchronizedStack</span><span><>(</span>
                    <span>SynchronizedStack</span><span>.</span><span>DEFAULT_SIZE</span><span>,</span>
                    <span>socketProperties</span><span>.</span><span>getProcessorCache</span><span>());</span>

            <span>// Start poller threads</span>
            <span>pollers</span> <span>=</span> <span>new</span> <span>Poller</span><span>[</span><span>getPollerThreadCount</span><span>()];</span>
            <span>for</span> <span>(</span><span>int</span> <span>i</span> <span>=</span> <span>0</span><span>;</span> <span>i</span> <span><</span> <span>pollers</span><span>.</span><span>length</span><span>;</span> <span>i</span><span>++)</span> <span>{</span>
                <span>pollers</span><span>[</span><span>i</span><span>]</span> <span>=</span> <span>new</span> <span>Poller</span><span>();</span>
                <span>Thread</span> <span>pollerThread</span> <span>=</span> <span>new</span> <span>Thread</span><span>(</span><span>pollers</span><span>[</span><span>i</span><span>]);</span>
                <span>pollerThread</span><span>.</span><span>start</span><span>();</span>
            <span>}</span>
        <span>}</span>
    <span>}</span>
<span>}</span>
public class NioEndpoint extends AbstractJsseEndpoint<NioChannel,SocketChannel> {

    private Poller[] pollers;
    private NioSelectorPool selectorPool;

    @Override
    protected void startInternal() throws Exception {
        // Initialize NIO components
        if (!running) {
            running = true;
            paused = false;

            // Create worker collection
            processorCache = new SynchronizedStack<>(
                    SynchronizedStack.DEFAULT_SIZE,
                    socketProperties.getProcessorCache());

            // Start poller threads
            pollers = new Poller[getPollerThreadCount()];
            for (int i = 0; i < pollers.length; i++) {
                pollers[i] = new Poller();
                Thread pollerThread = new Thread(pollers[i]);
                pollerThread.start();
            }
        }
    }
}

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4.2 NIO Channel Implementation 

<span>public</span> <span>class</span> <span>NioChannel</span> <span>implements</span> <span>ByteChannel</span> <span>{</span>
  <span>private</span> <span>final</span> <span>SocketChannel</span> <span>sc</span><span>;</span>
  <span>private</span> <span>final</span> <span>NioEndpoint</span> <span>endpoint</span><span>;</span>
  <span>@Override</span>
  <span>public</span> <span>int</span> <span>read</span><span>(</span><span>ByteBuffer</span> <span>dst</span><span>)</span> <span>throws</span> <span>IOException</span> <span>{</span>
    <span>return</span> <span>sc</span><span>.</span><span>read</span><span>(</span><span>dst</span><span>);</span>
  <span>}</span>
  <span>@Override</span>
  <span>public</span> <span>int</span> <span>write</span><span>(</span><span>ByteBuffer</span> <span>src</span><span>)</span> <span>throws</span> <span>IOException</span> <span>{</span>
    <span>return</span> <span>sc</span><span>.</span><span>write</span><span>(</span><span>src</span><span>);</span>
  <span>}</span>
<span>}</span>
<span>public</span> <span>class</span> <span>NioChannel</span> <span>implements</span> <span>ByteChannel</span> <span>{</span>
  <span>private</span> <span>final</span> <span>SocketChannel</span> <span>sc</span><span>;</span>
  <span>private</span> <span>final</span> <span>NioEndpoint</span> <span>endpoint</span><span>;</span>

  <span>@Override</span>
  <span>public</span> <span>int</span> <span>read</span><span>(</span><span>ByteBuffer</span> <span>dst</span><span>)</span> <span>throws</span> <span>IOException</span> <span>{</span>
    <span>return</span> <span>sc</span><span>.</span><span>read</span><span>(</span><span>dst</span><span>);</span>
  <span>}</span>

  <span>@Override</span>
  <span>public</span> <span>int</span> <span>write</span><span>(</span><span>ByteBuffer</span> <span>src</span><span>)</span> <span>throws</span> <span>IOException</span> <span>{</span>
    <span>return</span> <span>sc</span><span>.</span><span>write</span><span>(</span><span>src</span><span>);</span>
  <span>}</span>
<span>}</span>
public class NioChannel implements ByteChannel {
  private final SocketChannel sc;
  private final NioEndpoint endpoint;

  @Override
  public int read(ByteBuffer dst) throws IOException {
    return sc.read(dst);
  }

  @Override
  public int write(ByteBuffer src) throws IOException {
    return sc.write(src);
  }
}

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5. Performance Optimization

5.1 Thread Pool Configuration 

<span><Connector</span> <span>port=</span><span>"8080"</span> <span>protocol=</span><span>"HTTP/1.1"</span>
           <span>maxThreads=</span><span>"200"</span>
           <span>minSpareThreads=</span><span>"10"</span>
           <span>maxConnections=</span><span>"10000"</span>
           <span>acceptCount=</span><span>"100"</span>
           <span>connectionTimeout=</span><span>"20000"</span><span>/></span>
<span><Connector</span> <span>port=</span><span>"8080"</span> <span>protocol=</span><span>"HTTP/1.1"</span>
           <span>maxThreads=</span><span>"200"</span>
           <span>minSpareThreads=</span><span>"10"</span>
           <span>maxConnections=</span><span>"10000"</span>
           <span>acceptCount=</span><span>"100"</span>
           <span>connectionTimeout=</span><span>"20000"</span><span>/></span>
<Connector port="8080" protocol="HTTP/1.1"
           maxThreads="200"
           minSpareThreads="10"
           maxConnections="10000"
           acceptCount="100"
           connectionTimeout="20000"/>

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5.2 Buffer Size Optimization 

<span>public</span> <span>class</span> <span>ConnectorOptimizer</span> <span>{</span>
  <span>public</span> <span>void</span> <span>optimizeBuffers</span><span>(</span><span>Connector</span> <span>connector</span><span>)</span> <span>{</span>
    <span>// Set optimal buffer sizes</span>
    <span>connector</span><span>.</span><span>setProperty</span><span>(</span><span>"socketBuffer"</span><span>,</span> <span>"65536"</span><span>);</span>
    <span>connector</span><span>.</span><span>setProperty</span><span>(</span><span>"maxHttpHeaderSize"</span><span>,</span> <span>"8192"</span><span>);</span>
    <span>connector</span><span>.</span><span>setProperty</span><span>(</span><span>"maxPostSize"</span><span>,</span> <span>"2097152"</span><span>);</span>
  <span>}</span>
<span>}</span>
<span>public</span> <span>class</span> <span>ConnectorOptimizer</span> <span>{</span>
  <span>public</span> <span>void</span> <span>optimizeBuffers</span><span>(</span><span>Connector</span> <span>connector</span><span>)</span> <span>{</span>
    <span>// Set optimal buffer sizes</span>
    <span>connector</span><span>.</span><span>setProperty</span><span>(</span><span>"socketBuffer"</span><span>,</span> <span>"65536"</span><span>);</span>
    <span>connector</span><span>.</span><span>setProperty</span><span>(</span><span>"maxHttpHeaderSize"</span><span>,</span> <span>"8192"</span><span>);</span>
    <span>connector</span><span>.</span><span>setProperty</span><span>(</span><span>"maxPostSize"</span><span>,</span> <span>"2097152"</span><span>);</span>
  <span>}</span>
<span>}</span>
public class ConnectorOptimizer {
  public void optimizeBuffers(Connector connector) {
    // Set optimal buffer sizes
    connector.setProperty("socketBuffer", "65536");
    connector.setProperty("maxHttpHeaderSize", "8192");
    connector.setProperty("maxPostSize", "2097152");
  }
}

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6. Advanced Configuration

6.1 SSL Configuration 

<span><Connector</span> <span>port=</span><span>"8443"</span> <span>protocol=</span><span>"org.apache.coyote.http11.Http11NioProtocol"</span>
           <span>SSLEnabled=</span><span>"true"</span>
           <span>maxThreads=</span><span>"150"</span> <span>scheme=</span><span>"https"</span> <span>secure=</span><span>"true"</span>
           <span>keystoreFile=</span><span>"conf/localhost-rsa.jks"</span>
           <span>keystorePass=</span><span>"changeit"</span>
           <span>clientAuth=</span><span>"false"</span> <span>sslProtocol=</span><span>"TLS"</span><span>/></span>
<span><Connector</span> <span>port=</span><span>"8443"</span> <span>protocol=</span><span>"org.apache.coyote.http11.Http11NioProtocol"</span>
           <span>SSLEnabled=</span><span>"true"</span>
           <span>maxThreads=</span><span>"150"</span> <span>scheme=</span><span>"https"</span> <span>secure=</span><span>"true"</span>
           <span>keystoreFile=</span><span>"conf/localhost-rsa.jks"</span>
           <span>keystorePass=</span><span>"changeit"</span>
           <span>clientAuth=</span><span>"false"</span> <span>sslProtocol=</span><span>"TLS"</span><span>/></span>
<Connector port="8443" protocol="org.apache.coyote.http11.Http11NioProtocol"
           SSLEnabled="true"
           maxThreads="150" scheme="https" secure="true"
           keystoreFile="conf/localhost-rsa.jks"
           keystorePass="changeit"
           clientAuth="false" sslProtocol="TLS"/>

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6.2 Compression Setting 

<span><Connector</span> <span>port=</span><span>"8080"</span> <span>protocol=</span><span>"HTTP/1.1"</span>
           <span>compression=</span><span>"on"</span>
           <span>compressionMinSize=</span><span>"2048"</span>
           <span>noCompressionUserAgents=</span><span>"gozilla, traviata"</span>
           <span>compressableMimeType=</span><span>"text/html,text/xml,text/plain,text/css, text/javascript,application/javascript"</span><span>/></span>
<span><Connector</span> <span>port=</span><span>"8080"</span> <span>protocol=</span><span>"HTTP/1.1"</span>
           <span>compression=</span><span>"on"</span>
           <span>compressionMinSize=</span><span>"2048"</span>
           <span>noCompressionUserAgents=</span><span>"gozilla, traviata"</span>
           <span>compressableMimeType=</span><span>"text/html,text/xml,text/plain,text/css, text/javascript,application/javascript"</span><span>/></span>
<Connector port="8080" protocol="HTTP/1.1"
           compression="on"
           compressionMinSize="2048"
           noCompressionUserAgents="gozilla, traviata"
           compressableMimeType="text/html,text/xml,text/plain,text/css, text/javascript,application/javascript"/>

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7.Troubleshooting Guide

7.1 Common Issues and Solutions 

<span>public</span> <span>class</span> <span>ConnectorTroubleshooter</span> <span>{</span>
    <span>public</span> <span>void</span> <span>diagnoseConnector</span><span>(</span><span>Connector</span> <span>connector</span><span>)</span> <span>{</span>
        <span>// Check connection state</span>
        <span>if</span> <span>(!</span><span>connector</span><span>.</span><span>getState</span><span>().</span><span>isAvailable</span><span>())</span> <span>{</span>
            <span>// Check port availability</span>
            <span>if</span> <span>(!</span><span>isPortAvailable</span><span>(</span><span>connector</span><span>.</span><span>getPort</span><span>()))</span> <span>{</span>
                <span>throw</span> <span>new</span> <span>ConnectorException</span><span>(</span><span>"Port "</span> <span>+</span> <span>connector</span><span>.</span><span>getPort</span><span>()</span> <span>+</span> <span>" is in use"</span><span>);</span>
            <span>}</span>
            <span>// Check thread pool</span>
            <span>if</span> <span>(</span><span>connector</span><span>.</span><span>getProperty</span><span>(</span><span>"maxThreads"</span><span>)</span> <span>==</span> <span>null</span><span>)</span> <span>{</span>
                <span>logger</span><span>.</span><span>warn</span><span>(</span><span>"Thread pool not configured properly"</span><span>);</span>
            <span>}</span>
        <span>}</span>
    <span>}</span>
<span>}</span>
<span>public</span> <span>class</span> <span>ConnectorTroubleshooter</span> <span>{</span>
    <span>public</span> <span>void</span> <span>diagnoseConnector</span><span>(</span><span>Connector</span> <span>connector</span><span>)</span> <span>{</span>
        <span>// Check connection state</span>
        <span>if</span> <span>(!</span><span>connector</span><span>.</span><span>getState</span><span>().</span><span>isAvailable</span><span>())</span> <span>{</span>
            <span>// Check port availability</span>
            <span>if</span> <span>(!</span><span>isPortAvailable</span><span>(</span><span>connector</span><span>.</span><span>getPort</span><span>()))</span> <span>{</span>
                <span>throw</span> <span>new</span> <span>ConnectorException</span><span>(</span><span>"Port "</span> <span>+</span> <span>connector</span><span>.</span><span>getPort</span><span>()</span> <span>+</span> <span>" is in use"</span><span>);</span>
            <span>}</span>

            <span>// Check thread pool</span>
            <span>if</span> <span>(</span><span>connector</span><span>.</span><span>getProperty</span><span>(</span><span>"maxThreads"</span><span>)</span> <span>==</span> <span>null</span><span>)</span> <span>{</span>
                <span>logger</span><span>.</span><span>warn</span><span>(</span><span>"Thread pool not configured properly"</span><span>);</span>
            <span>}</span>
        <span>}</span>
    <span>}</span>
<span>}</span>
public class ConnectorTroubleshooter {
    public void diagnoseConnector(Connector connector) {
        // Check connection state
        if (!connector.getState().isAvailable()) {
            // Check port availability
            if (!isPortAvailable(connector.getPort())) {
                throw new ConnectorException("Port " + connector.getPort() + " is in use");
            }

            // Check thread pool
            if (connector.getProperty("maxThreads") == null) {
                logger.warn("Thread pool not configured properly");
            }
        }
    }
}

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7.2 Performance Monitor 

<span>public</span> <span>class</span> <span>ConnectorMonitor</span> <span>{</span>
    <span>private</span> <span>final</span> <span>JmxConnectorStats</span> <span>stats</span><span>;</span>
    <span>public</span> <span>void</span> <span>monitorConnector</span><span>()</span> <span>{</span>
        <span>// Monitor active connections</span>
        <span>int</span> <span>activeConnections</span> <span>=</span> <span>stats</span><span>.</span><span>getActiveConnections</span><span>();</span>
        <span>// Monitor request processing time</span>
        <span>long</span> <span>processingTime</span> <span>=</span> <span>stats</span><span>.</span><span>getProcessingTime</span><span>();</span>
        <span>// Monitor thread pool usage</span>
        <span>int</span> <span>activeThreads</span> <span>=</span> <span>stats</span><span>.</span><span>getCurrentThreadCount</span><span>();</span>
        <span>int</span> <span>maxThreads</span> <span>=</span> <span>stats</span><span>.</span><span>getMaxThreads</span><span>();</span>
        <span>// Log or alert if thresholds exceeded</span>
        <span>if</span> <span>(</span><span>activeConnections</span> <span>></span> <span>threshold</span><span>)</span> <span>{</span>
            <span>logger</span><span>.</span><span>warn</span><span>(</span><span>"Too many active connections: "</span> <span>+</span> <span>activeConnections</span><span>);</span>
        <span>}</span>
    <span>}</span>
<span>}</span>
<span>public</span> <span>class</span> <span>ConnectorMonitor</span> <span>{</span>
    <span>private</span> <span>final</span> <span>JmxConnectorStats</span> <span>stats</span><span>;</span>

    <span>public</span> <span>void</span> <span>monitorConnector</span><span>()</span> <span>{</span>
        <span>// Monitor active connections</span>
        <span>int</span> <span>activeConnections</span> <span>=</span> <span>stats</span><span>.</span><span>getActiveConnections</span><span>();</span>

        <span>// Monitor request processing time</span>
        <span>long</span> <span>processingTime</span> <span>=</span> <span>stats</span><span>.</span><span>getProcessingTime</span><span>();</span>

        <span>// Monitor thread pool usage</span>
        <span>int</span> <span>activeThreads</span> <span>=</span> <span>stats</span><span>.</span><span>getCurrentThreadCount</span><span>();</span>
        <span>int</span> <span>maxThreads</span> <span>=</span> <span>stats</span><span>.</span><span>getMaxThreads</span><span>();</span>

        <span>// Log or alert if thresholds exceeded</span>
        <span>if</span> <span>(</span><span>activeConnections</span> <span>></span> <span>threshold</span><span>)</span> <span>{</span>
            <span>logger</span><span>.</span><span>warn</span><span>(</span><span>"Too many active connections: "</span> <span>+</span> <span>activeConnections</span><span>);</span>
        <span>}</span>
    <span>}</span>
<span>}</span>
public class ConnectorMonitor {
    private final JmxConnectorStats stats;

    public void monitorConnector() {
        // Monitor active connections
        int activeConnections = stats.getActiveConnections();

        // Monitor request processing time
        long processingTime = stats.getProcessingTime();

        // Monitor thread pool usage
        int activeThreads = stats.getCurrentThreadCount();
        int maxThreads = stats.getMaxThreads();

        // Log or alert if thresholds exceeded
        if (activeConnections > threshold) {
            logger.warn("Too many active connections: " + activeConnections);
        }
    }
}

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Conclusion

Understanding Tomcat Connection is essential for:

  • Optimal performance tuning
  • Proper security configuration
  • Effective troubleshooting
  • Scalable application deployment

References

  • Apache Tomcat Connector Configuration Documentation
  • NIO Framework Documentation
  • Java Network Programming Guide
  • Performance Tuning Best Practices

原文链接：Tomcat Architecture Series-3.Mastering Tomcat Connector

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