🧵 Multi-threaded File Downloader (Simulated)

This project simulates a multi-threaded file downloader in C using POSIX threads (pthreads). The goal is to practice creating and managing threads, synchronizing access to shared resources, and simulating parallel file downloads.

📋 Description

Each file provided via command-line arguments is "downloaded" by a separate thread. The download is simulated by printing log messages and sleeping for a random duration. All threads run concurrently and the main thread waits for them to complete.

This project is inspired by Chapter 7 ("Threads") of Linux System Programming by Robert Love.

🚀 Usage

$ ./downloader file1.txt file2.txt file3.txt

Each file will be "downloaded" in parallel by a separate thread. The program prints informative messages about the start and completion of each download.

🛠️ Features

One thread per file
Simulated download using sleep()
Optional logging to file (future enhancement)
Thread-safe output via pthread_mutex_t
Clean thread termination via pthread_join

🧪 Example Output

[Thread 0x7fdc9a10]: Starting download of file1.txt
[Thread 0x7fdc9210]: Starting download of file2.txt
[Thread 0x7fdc9210]: Finished download of file2.txt
[Thread 0x7fdc9a10]: Finished download of file1.txt
All downloads complete.

📂 Project Structure

multidownload/
├── main.c         # Main program
├── Makefile       # Build script
└── README.md      # Project documentation

🧵 Concepts Practiced

Thread creation with pthread_create
Thread joining with pthread_join
Synchronization with pthread_mutex_t
Struct-based thread argument passing
Output race condition prevention

🏗️ Build

$ make

To clean the build:

$ make clean

📖 References

Linux System Programming by Robert Love — Chapter 7: Threads
POSIX Threads (man 7 pthread)

Last updated: 2025-07-28

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