The C++ programming language gives a ton of benefits to its users. It has various useful and efficient features and functionalities. In C++, Multithreading is one of the most important and useful features. Even today, Multithreading is one of the most used features. Let us learn more about it.<\/p>\n
Multithreading is more like multitasking. With the help of multitasking, you can run two or more programs on your computer concurrently. There are two ways of multitasking such as process-based and thread-based.<\/p>\n
The process-based multitasking helps in maintaining the concurrent execution of programs. And thread-based multitasking helps in handling the concurrent execution of pieces of the same program.<\/p>\n
The meaning of multithreading is that two or more threads running concurrently. And each thread is handling a different task. It allows you to perform many activities simultaneously. C++ does not provide any support for Multithreaded applications, it entirely relies upon the operating system.<\/p>\n
Let\u2019s take an example to understand it better.<\/p>\n
When you login to your Facebook account or you go to the news feed then you can see live videos, you can comment or even like that video, everything occurs simultaneously.<\/p>\n
A thread is a lightweight process. Each thread executes different parts of a program. And each thread shares memory and other system resources. All thread functions are declared in the <pthread.h> header file in linux.<\/p>\n
In this tutorial, we are going to use POSIX to write multithreaded C++ programs.<\/p>\n
POSIX threads provide API that are present on many UNIX-like operating systems such as OpenBSD, FreeBSD, GNU\/Linux, MAC OS X etc.<\/p>\n
You can create a thread using the pthread_create() funcion. In the above,<\/p>\n You can terminate any thread using the pthread_exit() function. Normally, the pthread_exit() routine is called after a thread has completed its work and it is not required to exist.<\/p>\n Example:- Creating threads in C++<\/strong><\/p>\n Output:-<\/strong><\/p>\n You can also join or detach threads in C++.<\/p>\n You have to use the join() function to join a thread. Main thread will terminate only after the termination of the child thread. Main thread waits for the child thread to complete execution.<\/p>\n Syntax:-<\/strong><\/p>\n You can also check if a thread is joinable or not using the joinable() function. It returns bool value.<\/p>\n Syntax:-<\/strong><\/p>\n You can detach a thread from the parent thread using the detach() function. In this, the main and child thread execute independently.<\/p>\n Example:- Using C++ join() function<\/strong><\/p>\n Output:-<\/strong><\/p>\n TechVidvan Tutorial: C++ Multithreading!<\/p>\n Created -> Thread T[0]! Example:- Using C++ detach() function<\/strong><\/p>\n Output:-<\/strong><\/p>\n You can pass multiple arguments to threads using a structure. You can pass any data type in a thread callback. Output:-<\/strong><\/p>\n In this tutorial, we discussed what is thread and multithreading in C++\u00a0 We also discussed how you can create and terminate a thread. Then we talked over the process of joining and detaching threads in C++. We discussed how you can pass arguments to threads.<\/p>\n","protected":false},"excerpt":{"rendered":" The C++ programming language gives a ton of benefits to its users. It has various useful and efficient features and functionalities. In C++, Multithreading is one of the most important and useful features. Even...<\/p>\n","protected":false},"author":1,"featured_media":84648,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[3405],"tags":[4287,4288,4289,4290],"class_list":["post-84634","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-cpp","tag-advantages-of-multithreading-in-c","tag-multithreading-in-c","tag-terminating-threads-in-c","tag-thread-in-c"],"yoast_head":"\n
\nSyntax:-<\/strong><\/p>\npthread_create(Idthread, attr, start_routine, arg)\n<\/pre>\n
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Terminating Threads in C++<\/h3>\n
#include <iostream>\n#include <pthread.h>\nusing namespace std;\n\nchar* st = \"Child thread\";\n\nvoid* fun(void *st)\n{\n cout << \"Created child thread: \" << (char*)st;\n}\nint main()\n{\n pthread_t t; \n pthread_create(&t, NULL, &fun, (void*)st);\n cout << \"Created Main thread!\" << endl;\n pthread_join(t, NULL);\n exit(EXIT_SUCCESS);\n return 0;\n}\n<\/pre>\n
\nCreated child thread: Child thread<\/div>\nJoining and Detaching threads in C++<\/h3>\n
join() function in C++<\/h4>\n
name_of_the_thread.join();\n<\/pre>\n
name_of_the_thread.joinable();\n<\/pre>\n
detach() function in C++<\/h4>\n
#include <iostream>\n#include <unistd.h> \n#include <pthread.h>\nusing namespace std;\n\nstring str;\nvoid* fun(void*)\n{\n sleep(1); \n cout << \"Created child thread \" << str << endl;\n}\n\nint main()\n{\n pthread_t t[4];\n cout << \"TechVidvan Tutorial: C++ Multithreading!\"<<endl<<endl;\n for(int i=0; i<4; i++)\n {\n \tcout << \"Created -> Thread T[\" << i << \"]!\" << str << endl;\n \tpthread_create(&t[i], NULL, &fun, NULL);\n \tpthread_join(t[i], NULL);\n}\nexit(EXIT_SUCCESS);\nreturn 0;\n}\n\n<\/pre>\n
\nCreated child thread
\nCreated -> Thread T[1]!
\nCreated child thread
\nCreated -> Thread T[2]!
\nCreated child thread
\nCreated -> Thread T[3]!
\nCreated child thread<\/p>\n<\/div>\n#include <iostream>\n#include <unistd.h> \n#include <pthread.h>\nusing namespace std;\n\nstring str;\nvoid* fun(void*)\n{\n sleep(1); \n cout << \"Created Child thread!\" << str << endl;\n}\n\nint main()\n{\n pthread_t t[4];\n for(int i=0; i<4; i++)\n {\n \tcout << \"Created -> Thread T[\" << i << \"]!\" << str << endl;\n \tpthread_create(&t[i], NULL, &fun, NULL);\n \tpthread_detach(t[i]);\n}\nexit(EXIT_SUCCESS);\nreturn 0;\n}\n<\/pre>\n
\nCreated -> Thread T[1]!
\nCreated -> Thread T[2]!
\nCreated -> Thread T[3]!<\/div>\nPassing arguments to threads in C++<\/h4>\n
\nExample:-<\/strong><\/p>\n#include <iostream>\n#include <cstdlib>\n#include <pthread.h>\n\nusing namespace std;\n\n#define NUM_THREADS 3\n\nstruct data{\n int thread_id;\n char *msg;\n};\n\nvoid *DisplayHi(void *thread_arg) {\n struct data *val;\n val = (struct data *) thread_arg;\n\n cout << \"Thread ID : \" << val->thread_id ;\n cout << \" Message : \" << val->msg << endl;\n\n pthread_exit(NULL);\n}\n\nint main () {\n pthread_t threads[NUM_THREADS];\n struct data td[NUM_THREADS];\n int rc;\n int i;\n\n for( i = 0; i < NUM_THREADS; i++ ) {\n \tcout <<\"Creating Thread: \" << i << endl;\n \ttd[i].thread_id = i;\n \ttd[i].msg = \"Just a friendly Message!\";\n \trc = pthread_create(&threads[i], NULL, DisplayHi, (void *)&td[i]);\n \t \n \tif (rc) {\n \tcout << \"Error:unable to create thread,\" << rc << endl;\n \texit(0);\n \t}\n }\n pthread_exit(NULL);\n} \n<\/pre>\n
\nCreating Thread: 1
\nThread ID : 0 Message : Just a friendly Message!
\nCreating Thread: 2
\nThread ID : 2 Message : Just a friendly Message!
\nThread ID : 1 Message : Just a friendly Message!<\/div>\nAdvantages of Multithreading in C++<\/h3>\n
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Summary<\/h3>\n