diff --git a/__concurrent/rayon/Cargo.lock b/__concurrent/rayon/Cargo.lock
new file mode 100644
index 0000000..a14bf2b
--- /dev/null
+++ b/__concurrent/rayon/Cargo.lock
@@ -0,0 +1,149 @@
+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
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+ "rayon 1.5.0",
+]
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+ "either",
+ "rayon-core",
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+dependencies = [
+ "crossbeam-channel",
+ "crossbeam-deque",
+ "crossbeam-utils",
+ "lazy_static",
+ "num_cpus",
+]
+
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diff --git a/__concurrent/rayon/Cargo.toml b/__concurrent/rayon/Cargo.toml
new file mode 100644
index 0000000..7524401
--- /dev/null
+++ b/__concurrent/rayon/Cargo.toml
@@ -0,0 +1,11 @@
+[package]
+name = "rayon"
+version = "0.1.0"
+authors = ["Hatter Jiang <jht5945@gmail.com>"]
+edition = "2018"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]
+rayon = "1.5.0"
+
diff --git a/__concurrent/rayon/src/main.rs b/__concurrent/rayon/src/main.rs
new file mode 100644
index 0000000..4f5dfab
--- /dev/null
+++ b/__concurrent/rayon/src/main.rs
@@ -0,0 +1,32 @@
+use rayon::prelude::*;
+
+fn main() {
+    println!("{}", sum_of_squares(&vec![11, 22, 3, 4, 5, 6, 7]));
+    println!("{}", fib_iterative(40));
+    println!("{}", fib_recursive(40));
+}
+
+fn sum_of_squares(input: &[i32]) -> i32 {
+    input.par_iter() // <-- just change that!
+         .map(|&i| i * i)
+         .sum()
+}
+
+fn fib_iterative(n: u128) -> u128 {
+    let mut a = 0;
+    let mut b = 1;
+    for _ in 0..n {
+        let c = a + b;
+        a = b;
+        b = c;
+    }
+    a
+}
+
+fn fib_recursive(n: u128) -> u128 {
+    if n < 2 {
+        return n;
+    }
+
+    fib_recursive(n - 1) + fib_recursive(n - 2)
+}