Updated April 15, 2023
Introduction to C++ thread join
The C++ thread join is one of the function it will execute after thread completion process so it synchronizes the functions and it returns the thread whenever the whole process execution is completed. If the thread operation is a success or failure, these synchronize blocks will always execute the thread that even calls to this function. It will either use the argument constructor or non-args constructor because it creates the instance of the function, and it will be used wherever its necessary. It will return the data type values or simply return void; after processing this function, the thread instance becomes a non-joinable one it can easily destroy for safety purposes.
Syntax of C++ thread join
The C++ thread join is used to blocks the threads until the first thread execution process is completed on which particular join() method is called to avoid the misconceptions or errors in the code. If suppose we are not using any join() method in the C++ code. It creates error automatically because the main methods are also one of the thread it runs whenever the code will be compiled or executed, so without the join() method or detach() method on the thread, it will display the run-time errors so the main() method thread will always been running on the back end.
#include<iostream.h>
#include<thread>
data type method name()
{
---some logic codes—
}
data type main()
{
std:: thread t (method name,integer);//create the threads
std::thread t1(method name,integer);//create the threads
t.join();
t1.join();
return value //if the data type is not void
}How thread join work in C++?
- The thread is one of the processes or operations while executing the multiple users running the same application simultaneously. Then, the thread will be needed to avoid the slowness in the application. Because we still used for to needed the any mutexes or any other conditions to avoid these type of scenarios in the application. When the thread joining is one of the most important concepts for the multi-threading because more threads will be accessed simultaneously. For each thread, the process execution time is different than other threads.
- So the one thread execution will be over, the other thread will be started until then, other threads are waiting else the dead lock will have occurred. To avoid the dead lock, we use synchronize concepts, and also here, we used the mutexes for to protect the other thread shared resources. It always allowed the main() method thread to wait for the all other threads to complete the tasks before quitting the threads themselves in the process. When we use std::thread.join function; it has some other types to continue creating or preventing, or destroying the other threads. So the performance-wise and to increase the probability of thread leaks, thread leaks, thread-runaway process, memory-runaway process or insufficient memory occurs these are the some other states for the thread joins.
- In the UI part, the code will handle the event handlers method because of this method to avoid and time consumption for the navigating the page in the application; the thread waits will also be avoided the unresponsive web pages to be reduced. It will more causes in the both unresponsive and uninterruptible threads. Similarly, the join() method has the same as some other parallel methods like TThread. WaitFor() etc., this method mainly covered for the multi-threading concepts. Even though the thread pooling, tasks, and other app-life time threads also some other inter-thread queues also included in these thread process except the join() method. The most important friendly method of the join is detach() method; these are also some of the threads called daemon threads or background threads. So we need to call the method called std::detach() method on the std::thread object.
Examples of C++ thread join
Given below are the examples of C++ thread join:
Example #1
Code:
#include <iostream>
#include <thread>
#include <chrono>
void first() {
std::this_thread::sleep_for(std::chrono::seconds(2));
}
void second() {
std::this_thread::sleep_for(std::chrono::seconds(4));
}
int main() {
std::cout << "Welcome To My Domain Starting the first thread.\n";
std::thread example(first);
std::cout << "Welcome To My Domain Starting the second thread...\n";
std::thread example1(second);
std::cout << "Thanks users we will waiting for the threads completion..." << std::endl;
example.join();
example1.join();
std::cout << "Thread completion is over !\n";
}Output:
Example #2
Code:
#include <iostream>
#include <thread>
#include <chrono>
void first(int a)
{
std::this_thread::sleep_for (std::chrono::seconds(a));
std::cout << "Welcome " << a << " User\n";
}
void second(int b)
{
std::this_thread::sleep_for (std::chrono::seconds(b));
std::cout << "Welcome " << b << "User 1\n";
}
void third(int c)
{
std::this_thread::sleep_for (std::chrono::seconds(c));
std::cout << "Welcome " << c << " User 2\n";
}
void four(int d)
{
std::this_thread::sleep_for (std::chrono::seconds(d));
std::cout << "Welcome " << d << " User 3\n";
}
void five(int e)
{
std::this_thread::sleep_for (std::chrono::seconds(e));
std::cout << "Welcome " << e << " User 4\n";
}
int main()
{
std::cout << "Welcome To My Domains..\n";
std::thread th (first,1);
std::thread th1 (second,2);
std::thread th2 (third,3);
std::thread th3 (four,4);
std::thread th4 (five,5);
std::cout << "Have a Nice Day Users Please wait for all other threads are to joining:\n";
th.join();
th1.join();
th2.join();
th2.join();
th3.join();
std::cout << "Thank you for your patience All the threads are joined\n";
return 0;
}Output:
Example #3
Code:
#include <chrono>
#include <iostream>
#include <thread>
using namespace std;
void first()
{
std::this_thread::sleep_for(
std::chrono::seconds(2));
}
int main()
{
std::thread th;
cout << "Welcome User the thread is created \n";
if (th.joinable())
cout << "The thread is joinable one\n";
else
cout << "The thread is non-joinable\n";
th = std::thread(first);
cout << "Waiting for thread joinable process \n";
if (th.joinable())
cout << "The thread is joinable on\n";
else
cout << "The thread is non-joinable\n";
th.join();
cout << "After the thread th is joinable we get the confirmation message \n";
if (th.joinable())
cout << "Thanks the therad is joined\n";
else
cout << "bad the thread is non-joinable\n";
return 0;
}Output:
Conclusion
In conclusion, the thread is one of the most important concepts for the web-based application as well as desktop applications; also, because the n number of users is accessed the apps at the same time, the performance of the apps also less it also decrease the bandwidth. So by using these thread.join() method is to reduce the memory consumption as well as to increase the more number of threads.
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This is a guide to C++ thread join. Here we discuss the introduction, how thread join works in C++? and examples, respectively. You may also have a look at the following articles to learn more –
