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.gitignore

···
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Cargo.lock

···
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Cargo.toml

···
+[package]
+name = "heater"
+version = "0.1.0"
+edition = "2024"
+
+[dependencies]
+clap = { version = "4.5.48", features = ["derive"] }
+ctrlc = "3.5.0"
+num_cpus = "1.17.0"

README.md

···
+# Heater 
+
+A Rust command-line application that churns your CPU cores at maximum capacity so your laptop isn't cold
+
+## Build
+
+```bash
+cargo build --release
+```
+
+The compiled binary will be at `target/release/heater`.
+
+## Usage
+
+### Run indefinitely (until Ctrl+C)
+```bash
+cargo run --release
+# or
+./target/release/heater
+```
+
+### Run for a specific duration (in seconds)
+```bash
+cargo run --release -- --duration 30
+# or
+./target/release/heater --duration 30
+```
+
+### Customize the number of free cores
+```bash
+# Leave 2 cores free
+cargo run --release -- --free-cores 2
+
+# Use ALL cores (leave 0 free)
+cargo run --release -- --free-cores 0
+
+# Run for 60 seconds, leaving 2 cores free
+cargo run --release -- --duration 60 --free-cores 2
+```
+
+## Options
+
+```
+-d, --duration <DURATION>      Duration to run in seconds (omit for indefinite run)
+-f, --free-cores <FREE_CORES>  Number of cores to leave free (default: 1)
+-h, --help                     Print help
+-V, --version                  Print version
+```

src/main.rs

···
+use clap::Parser;
+use std::sync::atomic::{AtomicBool, Ordering};
+use std::sync::Arc;
+use std::thread;
+use std::time::{Duration, Instant};
+
+#[derive(Parser, Debug)]
+#[command(author, version, about = "A CPU heater that churns CPU cores", long_about = None)]
+struct Args {
+    /// Duration to run in seconds (omit for indefinite run)
+    #[arg(short, long)]
+    duration: Option<u64>,
+
+    /// Number of cores to leave free (default: 1)
+    #[arg(short = 'f', long, default_value_t = 1)]
+    free_cores: usize,
+}
+
+fn main() {
+    let args = Args::parse();
+
+    // Get the number of logical CPU cores
+    let total_cores = num_cpus::get();
+    let cores_to_use = total_cores.saturating_sub(args.free_cores).max(1);
+
+    println!("Total CPU cores: {}", total_cores);
+    println!("Cores to heat: {}", cores_to_use);
+    println!("Cores to leave free: {}", args.free_cores);
+
+    match args.duration {
+        Some(seconds) => println!("Running for {} seconds", seconds),
+        None => println!("Running indefinitely (press Ctrl+C to stop)"),
+    }
+
+    // Set up signal handler for graceful shutdown
+    let running = Arc::new(AtomicBool::new(true));
+    let r = running.clone();
+
+    ctrlc::set_handler(move || {
+        println!("\nReceived Ctrl+C, shutting down...");
+        r.store(false, Ordering::SeqCst);
+    })
+    .expect("Error setting Ctrl-C handler");
+
+    let start_time = Instant::now();
+    let duration = args.duration.map(Duration::from_secs);
+
+    // Spawn threads to churn CPU
+    let mut handles = vec![];
+    for i in 0..cores_to_use {
+        let running = running.clone();
+        let handle = thread::spawn(move || {
+            println!("Thread {} started", i);
+            let mut counter: u64 = 0;
+            while running.load(Ordering::SeqCst) {
+                //compute something meaningless but CPU-intensive
+                counter = counter.wrapping_add(1);
+                for j in 0..1000 {
+                    counter = counter
+                        .wrapping_mul(1103515245)
+                        .wrapping_add(j)
+                        .wrapping_rem(2147483648);
+                }
+            }
+            println!("Thread {} stopped after {} iterations", i, counter);
+        });
+        handles.push(handle);
+    }
+
+    // Monitor duration if specified
+    if let Some(dur) = duration {
+        while start_time.elapsed() < dur && running.load(Ordering::SeqCst) {
+            thread::sleep(Duration::from_millis(100));
+        }
+        running.store(false, Ordering::SeqCst);
+    } else {
+        // Wait indefinitely until Ctrl+C
+        for handle in handles {
+            handle.join().unwrap();
+        }
+        return;
+    }
+
+    // Wait for all threads to finish
+    for handle in handles {
+        handle.join().unwrap();
+    }
+
+    println!("Finished heating for {:?}", start_time.elapsed());
+}