From 99dbbf25415d49d61efe60a62402bad26a9569c1 Mon Sep 17 00:00:00 2001
From: asthetik <aestheticslee@outlook.com>
Date: Fri, 10 Nov 2023 21:42:26 +0800
Subject: [PATCH] Optimize sample code

---
 .../concurrency-with-threads/thread.md        | 20 ++++++++++++++-----
 1 file changed, 15 insertions(+), 5 deletions(-)

diff --git a/src/advance/concurrency-with-threads/thread.md b/src/advance/concurrency-with-threads/thread.md
index bc6ef359..e71b1c06 100644
--- a/src/advance/concurrency-with-threads/thread.md
+++ b/src/advance/concurrency-with-threads/thread.md
@@ -413,20 +413,30 @@ use std::cell::Cell;
 use std::thread;
 
 let tls = Arc::new(ThreadLocal::new());
-
+let mut v = vec![];
 // 创建多个线程
 for _ in 0..5 {
     let tls2 = tls.clone();
-    thread::spawn(move || {
+    let handle = thread::spawn(move || {
         // 将计数器加1
+        // 请注意，由于线程 ID 在线程退出时会被回收，因此一个线程有可能回收另一个线程的对象
+        // 这只能在线程退出后发生，因此不会导致任何竞争条件
         let cell = tls2.get_or(|| Cell::new(0));
         cell.set(cell.get() + 1);
-    }).join().unwrap();
+    });
+    v.push(handle);
+}
+for handle in v {
+    handle.join().unwrap();
 }
-
 // 一旦所有子线程结束，收集它们的线程局部变量中的计数器值，然后进行求和
 let tls = Arc::try_unwrap(tls).unwrap();
-let total = tls.into_iter().fold(0, |x, y| x + y.get());
+let total = tls.into_iter().fold(0, |x, y| {
+    // 打印每个线程局部变量中的计数器值，发现不一定有5个线程，
+    // 因为一些线程已退出，并且其他线程会回收退出线程的对象
+    println!("x: {}, y: {}", x, y.get());
+    x + y.get()
+});
 
 // 和为5
 assert_eq!(total, 5);