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+====== thread_2.cc ======
+<file c++ thread_2.cc>
+#include <iostream>
+#include <thread>
+#include <mutex>
+using namespace::std;
+// gcc -std=c++11 thread_1.cc -lstdc++ -o thread_1
+std::mutex mu;
+void shared_print(string msg,int id) {
+  std::lock_guard<std::mutex> guard(mu);  // RAII - when guard goes out of scope
+  //mu.lock();  // if cout throws an exception then the program will be locked forever.
+  cout << msg << id << endl;  // still could mess up output if other process writes to cout.
+  //mu.unlock();
+}
+void fun1() {
+  cout << "Im in function 1"<<endl;
+}
+class Fctor {
+public:
+  void operator()(string& msg) {
+     for(int i=0;i>-10;i--)
+        // cout << msg << i <<endl;
+        shared_print(string(msg),i);
+  }
+};
+int main(void)
+{
+  string s = "Message from main.";
+  //std::thread t1((Fctor()),s);  // Parameters passed to a thread are always by value.
+  std::thread t1((Fctor()),std::ref(s));
+  // or you can use std::move(s)
+  // transfer ownership of thread
+  std::thread t2 = std::move(t1);
+  // print out the ID
+  cout << std::this_thread::get_id() << endl;
+  cout << t2.get_id() <<endl;
+  // Prevent Oversubscription - minimize context switching
+  // std::thread::hardware_concurrency();
+  try {
+    for(int i=0;i<10;i++)
+      // cout << "in main:"<<i<<endl;
+      shared_print(string("In Main:"),i);
+  } catch (...) {
+    t2.join();
+    throw;
+  }
+  t2.join();
+}
+</file>
+<file make Makefile>
+TARGETS=thread_1 thread_2
+all: $(TARGETS)
+% : %.cc
+    gcc -std=c++11 $^ -lstdc++ -o $@
+clean:
+    rm $(TARGETS)
+</file>

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