feat(c++/multi-thread-programming): add thread_local examples

c++/multi-thread-programming/ex23_thread_local.cpp

@@ -0,0 +1,35 @@
+#include <iostream>
+#include <vector>
+#include <thread>
+#include <atomic>
+
+using namespace std;
+
+// 각 쓰레드 단위로 접근 가능한 전역변수 취급
+thread_local int LThreadId = 0;
+
+void ThreadMain(int threadId)
+{
+    // 쓰레드 단위로 값 할당. 다른 쓰레드에 영향 미치지 않음.
+    LThreadId = threadId;
+
+    while (true)
+    {
+        cout << LThreadId << endl;
+        this_thread::sleep_for(std::chrono::milliseconds(1000));
+    }
+}
+
+int main()
+{
+    vector<thread> threads;
+    for (int i = 0; i < 10; i++)
+    {
+        int threadId = i + 1;
+        threads.push_back(thread(ThreadMain, threadId));
+    }
+    for (thread& t : threads)
+    {
+        t.join();
+    }
+}