Add code

example_2/.gitignore

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+/target

example_2/Cargo.toml

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+[package]
+name = "example_2"
+version = "0.1.0"
+edition = "2021"
+
+[dependencies]
+parking_lot = "0.12.3"
+crossbeam = "0.8.4"

example_2/src/main.rs

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+use crossbeam::scope;
+use parking_lot::{Mutex, MutexGuard};
+
+fn main() {
+    let mut counter = Mutex::new(0);
+
+    scope(|s| {
+        for _ in 0..10 {
+            s.spawn(|_| {
+                for _ in 0..10 {
+                    let mut guard: MutexGuard<i32> = counter.lock();
+                    *guard += 1;
+                }
+            });
+        }
+    })
+    .unwrap();
+
+    let total: &mut i32 = counter.get_mut();
+    println!("total = {}", *total)
+}