http://man7.org/linux/man-pages/man3/pthread_detach.3.html:
Either pthreadjoin(3) or pthreaddetach() should be called for each thread that an application creates, so that system resources for the thread can be released. (But note that the resources of all threads are freed when the process terminates.)
更多的解釋: [https://dotblogs.com.tw/brady/2010/09/09/17624]https://dotblogs.com.tw/brady/2010/09/09/17624