Multithreaded Web Server Project

A Java-based web server implementation demonstrating different threading approaches for handling multiple client connections. This project includes three different server implementations: Single-threaded, Multi-threaded, and Thread Pool-based servers, designed for performance testing with JMeter.

Features

• Single-threaded Server: Basic server implementation that handles clients sequentially
• Multi-threaded Server: Creates a new thread for each client connection
• Thread Pool Server: Uses a bounded thread pool with work queue for efficient resource management
• Client Applications: Test clients for each server implementation with concurrent connections
• Performance Testing: Optimized for JMeter load testing with 1000 threads per second
• Graceful Shutdown: All servers support graceful shutdown with Ctrl+C

Prerequisites

• Java Development Kit (JDK) 8 or higher
• Apache JMeter (for load testing)
• Basic understanding of Java networking and threading concepts

Requirements

• Java 8+
• No external dependencies required (uses only Java standard library)
• Apache JMeter 5.0+ (for performance testing)

How to Run

Single-Threaded Server

1. Compile the server:

   cd SingleThreaded
   javac Server.java

2. Run the server:

   java Server

3. In another terminal, compile and run the client:

   javac Client.java
   java Client

Multi-Threaded Server

1. Compile the server:

   cd MultiThreaded
   javac Server.java

2. Run the server:

   java Server

3. In another terminal, compile and run the client:

   javac Client.java
   java Client

Thread Pool Server

1. Compile the server:

   cd ThreadPool
   javac Server.java

2. Run the server:

   java Server

3. In another terminal, compile and run the client:

   javac Client.java
   java Client

Implementation Details

Single-Threaded Server

• Port: 8010
• Behavior: Handles one client at a time sequentially
• Use Case: Simple applications with low concurrency requirements
• Limitations: Can only serve one client simultaneously
• Features:
  • 30-second socket timeout
  • Graceful shutdown support
  • Proper resource cleanup

Multi-Threaded Server

• Port: 8010
• Behavior: Creates a new thread for each client connection
• Use Case: Applications requiring high concurrency
• Features:
  • Handles multiple clients simultaneously
  • Each client gets its own dedicated thread
  • 30-second socket timeout
  • Daemon threads for graceful shutdown
  • Proper resource cleanup

Thread Pool Server

• Port: 8010
• Thread Pool Size: 20 threads
• Queue Capacity: 100 requests
• Behavior: Uses bounded thread pool with work queue
• Use Case: Production-ready applications with controlled resource usage
• Features:
  • Bounded thread pool prevents resource exhaustion
  • Work queue with CallerRunsPolicy for backpressure
  • 30-second socket timeout
  • Active thread monitoring
  • Graceful shutdown with timeout
  • Proper resource cleanup

Client Applications

• Single-threaded Client: Simple client that connects once
• Multi-threaded Client: Creates 100 concurrent connections to test server performance
• Thread Pool Client: Uses thread pool to create 100 concurrent connections

Performance Characteristics

Implementation	Concurrency	Resource Usage	Scalability	JMeter Performance
Single-threaded	Low	Minimal	Limited	~1 TPS
Multi-threaded	High	High	Good	~500-800 TPS
Thread Pool	High	Moderate	Excellent	~800-1000+ TPS

Testing

Manual Testing

Each client creates multiple concurrent connections to test server performance:

cd ThreadPool
java Client

This will create 100 threads, each establishing a connection to the server simultaneously.

JMeter Load Testing

Setup JMeter Test Plan

1. Create Thread Group:

   • Number of Threads: 1000
   • Ramp-up period: 10 seconds
   • Loop Count: 1

2. Add TCP Sampler:

   • Server Name: localhost
   • Port: 8010
   • Send: Hello from JMeter Client\n
   • Response Timeout: 5000ms

3. Add Listeners:

   • View Results Tree
   • Aggregate Report
   • Response Time Graph

Expected Performance Results

Single-threaded Server:

• Throughput: ~1-5 TPS
• Response Time: High (queuing)
• Error Rate: High under load

Multi-threaded Server:

• Throughput: ~500-800 TPS
• Response Time: Moderate
• Error Rate: Low to moderate

Thread Pool Server:

• Throughput: ~800-1000+ TPS
• Response Time: Low
• Error Rate: Very low

Expected Output

Server Output:

ThreadPool Server is listening on port 8010
Thread pool size: 20
Queue capacity: 100
Press Ctrl+C to stop the server
New client connected: /127.0.0.1 (Active threads: 1)
Client [/127.0.0.1] says: Hello from Client 0 [/127.0.0.1:54321]

Client Output:

Starting 100 concurrent clients...
Client 0 received: Hello Client! -- from the ThreadPool Server
Client 1 received: Hello Client! -- from the ThreadPool Server
...
All clients completed.

Key Concepts Demonstrated

1. Socket Programming: Basic client-server communication using Java sockets
2. Threading Models: Different approaches to handling concurrent connections
3. Resource Management: How different threading models affect resource usage
4. Network Programming: TCP/IP communication fundamentals
5. Performance Optimization: Thread pool configuration for high throughput
6. Load Testing: JMeter integration for performance validation