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--- c:c_threads:troubleshooting:program_crashes [2021/06/07 08:41] – peter
+++ c:c_threads:troubleshooting:program_crashes [2021/06/09 11:10] (current) – peter
@@ Line 1: / Line 1: @@
 ====== C - C++ Threads - Troubleshooting - Program Crashes ======
-Forgetting to join a thread or detach it (make it unjoinable) before the main program terminates, will cause in a program crash.
+[[C:C++ Threads:Troubleshooting:Program Crashes:Forgetting to join a thread|Forgetting to join a thread]]
-For example, the t1 thread is not joined to the main thread.
+[[C:C++ Threads:Troubleshooting:Program Crashes:Trying to acquire a std::mutex twice|Trying to acquire a std::mutex twice]]
-<code cpp>
+[[C:C++ Threads:Troubleshooting:Program Crashes:Not handling exceptions in background threads|Not handling exceptions in background threads]]
-#include <iostream>
-#include <thread>
-using namespace std;
-void HelloWorld()
-{
-  cout << "Hello World" << endl;
-}
-int main()
-{
-  thread t1(HelloWorld);
-  //t1.join();  // If the thread is not joined to the main thread it will cause a crash.
-  return 0;
-}
-</code>
-<WRAP info>
-**NOTE:**  Why does it crash ???
-  * This is because, at the end of the main function, thread t1 goes out of scope and the thread destructor is called.
-  * Inside the destructor, a check is performed to see if thread t1 is joinable.
-  * A joinable thread is a thread that has not been detached.
-  * If the thread is joinable, std::terminate is called.
-</WRAP>
-----
-===== Resolution =====
-There are two ways to fix this depending on your needs.
-==== 1.  Join the thread t1 to the main thread ====
-<code cpp>
-int main()
-{
-  thread t1(HelloWorld);
-  t1.join();  // Join t1 to the main thread.
-  return 0;
-}
-</code>
-----
-==== 2. Detach the thread t1 from the main thread and let it continue as a daemon thread ====
-<code cpp>
-int main()
-{
-  thread t1(HelloWorld);
-  t1.detach();  // Detach t1 from main thread.
-  return 0;
-}
-</code>
-----