High-Performance Multithreaded HTTP Proxy Server in Java

Track your progress by marking chapters as completed.

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Progress Tracker

• [ ] Chapter 1: Java Networking Essentials
• [ ] Chapter 2: Threading Models and Thread Pools
• [ ] Chapter 3: HTTP Request & Response Parsing
• [ ] Chapter 4: Proxy Logic & Request Forwarding
• [ ] Chapter 5: Asynchronous Execution with CompletableFuture
• [ ] Chapter 6: Memory Handling and Performance Tuning
• [ ] Chapter 7: Using Java NIO for Non-blocking IO
• [ ] Chapter 8: Virtual Threads (Project Loom)
• [ ] Chapter 9: Logging, Rate Limiting & Monitoring
• [ ] Chapter 10: Benchmarking and Load Testing

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Chapter 1: Java Networking Essentials

Goal: Understand how low-level TCP/IP communication works in Java

Topics:

• ServerSocket, Socket
• Basic request-response flow
• Reading and writing raw bytes

Outcome: Create a simple blocking server that accepts HTTP requests and echoes a response.

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Chapter 2: Threading Models and Thread Pools

Goal: Learn thread-per-connection vs thread-pooling models

Topics:

• Thread, Runnable, ExecutorService
• Thread lifecycle, thread leaks, deadlocks
• Fixed vs cached thread pools

Outcome: Refactor proxy to use a thread pool for efficient client connection handling.

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Chapter 3: HTTP Request & Response Parsing

Goal: Implement minimal HTTP parsing logic

Topics:

• Reading request headers and bodies
• Extracting host, path, method
• Understanding response codes and headers

Outcome: Proxy parses incoming HTTP requests and forwards them properly.

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Chapter 4: Proxy Logic & Request Forwarding

Goal: Relay client requests to destination server and return the response

Topics:

• Handling multiple open sockets (client ↔ proxy ↔ destination)
• Connecting to external servers using sockets
• Stream piping and buffering

Outcome: Functional proxy intercepting, forwarding, and returning HTTP responses.

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Chapter 5: Asynchronous Execution with CompletableFuture

Goal: Use async constructs for non-blocking processing

Topics:

• CompletableFuture basics
• Chaining, combining, exception handling
• CPU-bound vs IO-bound async tasks

Outcome: Convert blocking proxy steps to non-blocking with CompletableFuture.

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Chapter 6: Memory Handling and Performance Tuning

Goal: Profile and optimize heap & off-heap memory use

Topics:

• ByteBuffer, BufferedReader, GC behavior
• Avoiding memory leaks
• Buffer pooling

Outcome: Tune proxy for high traffic without OOMs or GC issues.

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Chapter 7: Using Java NIO for Non-blocking IO

Goal: Migrate to Java NIO for async, scalable IO

Topics:

• Selector, Channel, SelectionKey
• Event-driven loop
• Tradeoffs vs threads

Outcome: Implement lightweight event-loop proxy server (optional but powerful).

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Chapter 8: Virtual Threads (Project Loom)

Goal: Use lightweight threads for massive concurrency

Topics:

• Thread.ofVirtual().start(...)
• Blocking code, simplified
• When to use virtual vs platform threads

Outcome: Re-implement proxy with virtual threads for scalable design.

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Chapter 9: Logging, Rate Limiting & Monitoring

Goal: Make proxy production-aware

Topics:

• Logging libraries: SLF4J, Logback
• Adding request logs, errors, timing
• Basic rate limiting (per IP)

Outcome: Proxy logs access and protects against abuse.

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Chapter 10: Benchmarking and Load Testing

Goal: Test real-world performance under load

Topics:

• wrk, ab, JMH for benchmarking
• Metrics: latency, throughput, memory usage
• Tuning thread pool, buffer sizes

Outcome: Have performance numbers to compare implementations.

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Final Deliverable

A fast, clean Java HTTP proxy server handling thousands of concurrent connections with efficient threading, memory management, and network handling.

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Happy coding! Mark your progress above as you go.